In May 2023, the LIGO Livingston observatory detected the likely black hole-neutron star (BHNS) merger GW230529_181500. That event is expected to be the merger of a 2.5-4.5 $M_{\odot}$ primary with a secondary compact object of mass between 1.2-2.0 $M_{\odot}$. This makes it the first BHNS merger with a significant potential for the production of electromagnetic (EM) counterparts, and provides further evidence for compact objects existing within the suspected lower mass gap. To produce post-merger EM transients, the component of the black hole spin aligned with the orbital angular momentum must be sufficiently high, allowing the neutron star to be tidally disrupted. The disrupting BHNS binary may then eject a few percent of a solar mass of matter, leading to an observable kilonova driven by radioactive decays in ejecta, and/or a compact-binary GRB (cbGRB) resulting from the formation of an accretion disk and relativistic jet. Determining which mergers lead to disruption of the neutron star is necessary to predict the prevalence of EM signals from BHNS mergers, yet most BHNS simulations so far have been performed far from the minimum spin required for tidal disruption. Here, we use the Spectral Einstein Code (SpEC) to explore the behavior of BHNS mergers in a mass range consistent with GW230529_181500 close to that critical spin, and compare our results against the mass remnant model currently used by the LVK collaboration to predict the probability of tidal disruption. Our numerical results reveal the emergence of non-zero accretion disks even below the predicted NS disruption limit, of low mass but capable of powering cbGRBs. Our results also demonstrate that the remnant mass model underpredicts the disk mass for the DD2 EOS, while they are within expected modeling errors for SFHo. In all of our simulations, any kilonova signal would be dim and dominated by post-merger disk outflows.

Astronomy & Astrophysics (A&A;) is an international journal which publishes papers on all aspects of astronomy and astrophysics

Астрономы зафиксировали уникальное явление — сверхновую SN 2023zkd, чье поведение кардинально отличалось от всех известных ранее. После взрыва она постепенно угасала, но спустя несколько месяцев неожиданно вспыхнула вновь. Ученые предполагают, что ключевую роль в этой катастрофе сыграла черная

Magnetic fields play important roles in the star-formation process across different spatial scales. The interplay between magnetic field strength (a key component of the interstellar medium's energy budget) and field orientation relative to density structures impacts how interstellar material evolves toward star formation. To understand galactic evolution toward stars, planets, and ultimately life, we need to map three-dimensional (3D) magnetic field vectors in 3D space. However, determining full vector information remains challenging due to projection effects and the complex relationship between observable tracers and field geometry. We outline the observational techniques that can be used to probe the 3D magnetic field structures of objects such as supernova remnants (SNR), superbubbles, HII regions, and HI filaments in the diffuse interstellar medium (ISM), and objects in the dense ISM such as molecular clouds, filaments, and cores. The main SKA-specific observational techniques include synchrotron emission and Faraday rotation of both compact sources and the diffuse emission. We discuss how SKA AA4 will allow implementation of the techniques we describe, leveraging the vastly improved sensitivity, resolution and uv-coverage compared to existing datasets. This will enhance our ability to reconstruct 3D magnetic field vectors, advancing our understanding of magnetic fields in Galactic evolution and star formation.

Every human being who has ever looked at the night sky has wondered about the future. We wonder what tomorrow will bring, what will happen to our planet, and what fate awaits humanity. Yet there is a much bigger question—one so enormous that it stretches beyond Earth, beyond the Sun, beyond the Milky Way, and beyond every galaxy visible in the cosmos. What will happen to the universe itself? Will the stars shine forever? Will galaxies continue drifting through space for eternity? Or will everything eventually come to an end? For most of human history, these questions belonged to philosophy, religion, and imagination. There was no way to scientifically investigate the ultimate destiny of the cosmos. The universe seemed timeless and unchanging. Modern astronomy changed everything. Over the past century, scientists have discovered that the universe has a history. It was born approximately 13.8 billion years ago in the Big Bang. It has evolved ever since. Galaxies formed, stars ignited, planets emerged, and life appeared. If the universe had a beginning, it is reasonable to ask whether it also has an ending. Today, astronomers and physicists have developed several possible scenarios for the far future of the cosmos. Among the most fascinating—and most dramatic—are two ideas known as the Big Freeze and the Big Rip. One predicts a universe that slowly fades into eternal darkness and cold. The other predicts a universe that is violently torn apart, from galaxies all the way down to atoms themselves. Both possibilities emerge from our understanding of cosmic expansion, gravity, and one of the greatest mysteries in modern science: dark energy. The story of the universe’s future is not merely about stars and galaxies. It is ultimately about the fate of everything that exists. ## Understanding the Expanding Universe To understand the future, we first need to understand the present. One of the most revolutionary discoveries in science occurred during the early twentieth century when astronomers realized that the universe is expanding. Before this discovery, many scientists assumed the cosmos was static. Galaxies were thought to remain roughly fixed in place. Observations changed that picture. Astronomers found that distant galaxies are moving away from us. More surprisingly, the farther away a galaxy is, the faster it appears to recede. This does not mean Earth occupies the center of the universe. Instead, space itself is expanding. A helpful analogy is raisins embedded in rising bread dough. As the dough expands, every raisin moves farther away from every other raisin. No single raisin occupies a special position. The universe behaves similarly. Galaxies are not simply flying through empty space. The fabric of space itself is stretching. This discovery transformed cosmology and laid the foundation for modern theories about the universe’s future. ## The Legacy of the Big Bang The expanding universe strongly suggests that everything was once much closer together. If we mentally reverse cosmic expansion, galaxies converge toward a hotter, denser state in the distant past. This idea became the basis for the Big Bang theory. According to current evidence, the observable universe began approximately 13.8 billion years ago in an extremely hot and dense state. As space expanded, temperatures dropped. Particles formed. Atoms emerged. Stars ignited. Galaxies assembled. Over billions of years, the universe evolved into the rich cosmic landscape we observe today. But expansion did not stop. The universe continues growing larger every second. The critical question is what happens next. ## Gravity and the Fate of the Cosmos For much of the twentieth century, scientists believed gravity would determine the universe’s ultimate fate. Gravity attracts matter. Every galaxy pulls on every other galaxy. The combined gravity of all matter in the universe acts as a cosmic brake on expansion. Astronomers considered several possibilities. If gravity were strong enough, expansion might eventually stop and reverse. Galaxies would begin moving closer together. The universe would contract. Eventually, everything might collapse into a hot, dense state called the Big Crunch. If gravity were weaker, expansion would continue forever but gradually slow down. Galaxies would keep drifting apart, though at a decreasing rate. For decades, scientists worked to determine which scenario matched reality. Then a stunning discovery changed everything. ## The Discovery That Shocked Cosmology In the late 1990s, two independent research teams studied distant exploding stars called Type Ia supernovae. These stellar explosions serve as cosmic distance markers. By measuring their brightness, astronomers can estimate how far away they are. The researchers expected to find evidence that cosmic expansion was slowing due to gravity. Instead, they found the opposite. The expansion of the universe is accelerating. Galaxies are not merely moving apart. They are moving apart faster and faster over time. The discovery was astonishing. Gravity should slow expansion. Something else appeared to be overpowering gravity on cosmic scales. Scientists called this mysterious phenomenon dark energy. Today, dark energy represents one of the greatest unsolved puzzles in physics. ## What Is Dark Energy? Dark energy is not a substance we can see. It emits no light. It cannot be directly photographed. Its existence is inferred from its effects on the universe. Whatever dark energy is, it appears to act as a kind of cosmic repulsion. Instead of pulling matter together like gravity, it pushes space apart. Current observations suggest dark energy accounts for roughly 68 percent of the universe’s total energy content. Ordinary matter—the stuff that makes up stars, planets, and people—accounts for only a small fraction. This means the future of the universe may depend largely on something we barely understand. The behavior of dark energy determines which cosmic ending is most likely. ## Why Predicting the Future Is Difficult Predicting the future of the universe is not like forecasting tomorrow’s weather. The timescales involved are almost unimaginable. Millions of years seem long to humans. Billions of years define geological and cosmic history. The ultimate fate of the universe unfolds across trillions, quadrillions, and even vastly longer spans of time. Tiny uncertainties in our understanding of dark energy become enormously important over such durations. Scientists therefore discuss possible futures rather than absolute certainties. Among these possibilities, two scenarios have attracted particular attention. The first is the Big Freeze. The second is the Big Rip. Each paints a dramatically different picture of cosmic destiny. ## The Big Freeze: A Slow Fade into Darkness The Big Freeze is currently considered the most likely long-term scenario based on available evidence. Its name sounds dramatic, but the process unfolds incredibly slowly. There is no sudden catastrophe. No cosmic explosion. No violent destruction. Instead, the universe gradually grows colder, darker, and emptier over unimaginable periods of time. Expansion continues forever. Galaxies drift farther apart. Stars eventually stop forming. Existing stars burn out. The cosmos slowly loses its sources of light and energy. Eventually, the universe approaches a state known as heat death. This represents the ultimate consequence of cosmic aging. ## Why Expansion Leads to Cooling The Big Freeze arises naturally from continued expansion. As space expands, matter becomes increasingly spread out. Galaxies move farther apart. Gas clouds become less dense. Opportunities for new star formation decrease. Think of a campfire. When logs are close together, the fire burns strongly. Spread them apart, and the fire weakens. The universe behaves similarly. As matter disperses, the conditions necessary for creating new stars become increasingly rare. Over time, the cosmic engine of star formation slows and eventually nearly stops. Without new stars replacing old ones, the universe gradually dims. ## The End of Stellar Birth Today, galaxies continue producing new stars. Vast clouds of hydrogen collapse under gravity. Nuclear fusion ignites. New suns are born. This process cannot continue forever. The supply of star-forming gas is finite. Much of it has already been converted into stars. As galaxies age, their gas reservoirs shrink. Eventually, star formation rates decline dramatically. Future galaxies may become dominated by aging stars with few replacements. Astronomers estimate that the era of significant star formation will eventually come to an end. The universe will enter a quieter chapter. ## When the Stars Begin to Die Stars are not eternal. They shine because nuclear fusion converts lighter elements into heavier ones. Fusion releases energy that radiates into space. Eventually, the fuel runs out. Small stars die relatively gently. Large stars often end in spectacular supernova explosions. Either way, every star has a limited lifespan. Our Sun, for example, has roughly five billion years remaining before it transforms into a red giant and eventually becomes a white dwarf. Far in the future, the stars visible today will all be gone. Only stellar remnants will remain. ## A Universe of Stellar Corpses After the era of active stars ends, the cosmos will be populated primarily by stellar remnants. White dwarfs will linger as cooling embers. Neutron stars will persist as incredibly dense objects. Black holes will continue lurking in the darkness. These remnants represent the final stages of stellar evolution. The sky, if anyone existed to observe it, would look profoundly different. Bright stellar populations would disappear. Galaxies would become darker and quieter. The age of stars would give way to the age of remnants. ## The Isolation of Galaxies As expansion accelerates, distant galaxies move away increasingly rapidly. Eventually, many galaxies will recede beyond our observable horizon. Their light will never reach us. Future observers within the Milky Way’s descendants may see only their local galactic neighborhood. The broader universe could become invisible. Ironically, future civilizations might not even know other galaxies exist. Evidence of the Big Bang itself could become inaccessible. The expanding universe gradually erases its own history from view. Cosmic isolation becomes one of the defining features of the far future. ## Black Holes Take Center Stage For immense periods of time, black holes may dominate the universe. These extraordinary objects possess gravitational fields so strong that not even light can escape once it crosses the event horizon. Black holes can grow by consuming matter and merging with one another. Galactic centers often host supermassive black holes containing millions or billions of solar masses. As stars disappear, black holes become increasingly important cosmic actors. Yet even black holes may not survive forever. ## Hawking Radiation and the Slow Death of Black Holes In the 1970s, physicist Stephen Hawking proposed a remarkable idea. Quantum effects near a black hole’s event horizon should cause black holes to slowly lose energy. This process is known as Hawking radiation. Over enormous timescales, black holes gradually evaporate. For stellar-mass black holes, the process takes far longer than the current age of the universe. Supermassive black holes survive even longer. Yet given enough time, even these cosmic giants eventually disappear. Their evaporation marks another step toward cosmic darkness. ## Heat Death of the Universe The ultimate stage of the Big Freeze is often called heat death. The phrase can be misleading. The universe does not become hot. Instead, it reaches maximum entropy. Entropy measures the dispersal of energy. As entropy increases, usable energy becomes increasingly scarce. Eventually, energy differences disappear. No significant work can be performed. No stars shine. No planets remain habitable. No complex structures arise. The universe becomes cold, dark, and nearly featureless. Matter drifts through vast expanses of empty space. This is the final vision of the Big Freeze. ## The Emotional Weight of the Big Freeze There is something haunting about the Big Freeze. It is not a dramatic ending. It is a fading. A slow extinguishing of cosmic lights. Stars vanish one by one. Galaxies grow isolated. The universe becomes quieter with every passing age. The Big Freeze resembles an endlessly dying sunset stretched across trillions upon trillions of years. Many scientists find this scenario both beautiful and melancholy. It reflects the inexorable consequences of thermodynamics played out on the grandest possible scale. ## Enter the Big Rip While the Big Freeze is currently favored, another possibility remains scientifically intriguing. This scenario is called the Big Rip. Unlike the slow fading of the Big Freeze, the Big Rip is violent. It predicts that expansion accelerates so dramatically that eventually every structure in the universe is torn apart. Galaxies separate. Stars are ripped from galaxies. Planets leave their stars. Atoms themselves are destroyed. Space expands with such intensity that nothing remains intact. The Big Rip represents one of the most extreme endings ever proposed. ## How the Big Rip Works The Big Rip depends on the behavior of dark energy. In standard cosmological models, dark energy maintains a relatively constant influence. Expansion accelerates steadily but not catastrophically. The Big Rip requires something different. Dark energy must grow stronger over time. Its repulsive effect must increase as the universe expands. If this occurs, expansion eventually overwhelms every force that binds structures together. Gravity loses the battle. Then stronger forces begin losing as well. The destruction unfolds in stages. ## Galaxies Torn Apart Initially, the universe may appear relatively normal. Galaxies continue drifting apart at increasing speeds. Eventually, however, expansion becomes strong enough to overcome the gravitational forces holding galaxies together. Stars begin escaping their galactic homes. The familiar structures of spiral and elliptical galaxies unravel. What took billions of years to assemble begins falling apart. Cosmic architecture dissolves. Galaxies become loose collections of stars drifting into isolation. ## The Destruction of Solar Systems As dark energy continues strengthening, the crisis deepens. Eventually, the force of expansion exceeds the gravitational attraction between stars and planets. Solar systems become unstable. Planets drift away from their parent stars. Orbits collapse. The intricate celestial dances that have persisted for billions of years come to an end. Earth, if it still existed, would no longer circle the Sun. Every planetary system throughout the universe would suffer the same fate. ## Stars Under Attack The next stage is even more dramatic. Expansion becomes strong enough to overwhelm the gravity holding stars together. Stars are no longer stable. The immense pressure and gravity that maintain stellar structure lose their ability to resist cosmic expansion. Stars literally come apart. Their matter disperses into space. The universe begins destroying not only galaxies and solar systems but the stars themselves. ## The Final Moments As the Big Rip approaches, expansion grows increasingly violent. The intervals between destructive stages become shorter. Eventually, even molecules can no longer remain intact. Chemical bonds fail. Atoms disintegrate. Finally, the fundamental particles themselves may be separated. At the ultimate moment, space-time reaches a catastrophic state. Everything that exists is torn apart. The universe ends not in darkness but in disintegration. ## Which Scenario Is More Likely? Current observations favor the Big Freeze. Measurements indicate that dark energy behaves in a way consistent with continued acceleration but not runaway growth. This suggests the universe will keep expanding forever without reaching the catastrophic conditions required for a Big Rip. However, scientists remain cautious. Dark energy remains poorly understood. Future observations could reveal unexpected behavior. Cosmology has repeatedly surprised humanity. Ideas once considered certain have been overturned by new evidence. For now, the Big Freeze appears more probable, but the story remains unfinished. ## Other Possible Endings The Big Freeze and Big Rip are not the only proposed fates of the cosmos. Some models allow for a future collapse known as the Big Crunch. Others suggest cyclic universes that repeatedly expand and contract. There are theories involving vacuum decay, in which a fundamental quantum transition could radically alter reality itself. Each scenario depends on details of physics that remain incompletely understood. The future of the universe remains one of science’s greatest open questions. ## Why the Universe’s Fate Matters At first glance, these events seem irrelevant. After all, they occur trillions or vastly more years in the future. Human civilization will not witness them. Yet studying the universe’s fate matters profoundly. Understanding the future helps us understand the present. The same physical laws that determine cosmic destiny govern stars, galaxies, and space today. Questions about the universe’s ending also reveal something deeply human. We are storytellers. We seek beginnings and endings. We want to understand where we came from and where everything is going. The future of the universe represents the largest chapter of all. ## Humanity’s Place in the Cosmic Story When contemplating the end of the universe, it is easy to feel insignificant. The cosmos is unimaginably vast. Its timescales dwarf human history. Entire civilizations rise and fall in the blink of cosmic time. Yet there is another perspective. The universe has produced beings capable of asking questions about its own destiny. Atoms forged inside ancient stars eventually became living creatures that can study galaxies and predict the far future. That fact is extraordinary. Whether the universe ends in freezing darkness or catastrophic disintegration, it has already generated something remarkable: awareness. ## The Beauty of an Unfinished Mystery One of the most exciting aspects of modern cosmology is that we do not yet know the answer. Scientists continue observing distant galaxies, measuring cosmic expansion, and investigating dark energy. New telescopes and future discoveries may transform our understanding. The ultimate fate of the cosmos remains an active scientific mystery. Unlike ancient generations who could only speculate, humanity now possesses tools capable of uncovering real answers. Every observation brings us a little closer to understanding the future written into the fabric of space and time. ## Conclusion The future of the universe depends largely on the nature of dark energy and the continuing expansion of space. Two of the most compelling possibilities are the Big Freeze and the Big Rip. In the Big Freeze scenario, which currently appears most likely, the universe expands forever, stars eventually die, galaxies become isolated, black holes evaporate, and the cosmos slowly fades into a cold, dark state of maximum entropy. In the Big Rip scenario, dark energy grows increasingly powerful until it tears apart galaxies, stars, planets, atoms, and ultimately space-time itself. Both possibilities emerge from the same remarkable discovery: the universe is not static but expanding at an accelerating rate. While current evidence favors the Big Freeze, the true nature of dark energy remains one of science’s greatest mysteries, leaving room for alternative outcomes. Whatever the final answer proves to be, the quest to understand the universe’s destiny is among humanity’s most profound scientific journeys. It connects us to the largest questions imaginable and reminds us that we are part of a cosmic story still being written—one whose final chapter remains hidden somewhere in the distant future of the stars.

За последние десять лет физики поймали почти четыре сотни гравитационных сигналов от столкновений черных дыр, но до сих пор не зафиксировали ни одной волны от коллапса сверхновой. Исследователи из Мельбурнского университета экстренно настраивают детекторы на нужные частоты, надеясь первыми «услышать» предсмертную агонию массивной звезды, которая, по всем статистическим выкладкам, запаздывает уже на три столетия. Когда звезда исчерпывает запасы термоядерного топлива, она не просто тихо гаснет. Звезды, чья масса превышает солнечную как минимум в восемь раз, заканчивают свою жизнь одним из самых высокоэнергетических событий во Вселенной — взрывом сверхновой с коллапсирующим ядром (core-collapse supernova). **_Поддержать нас на Boosty_** ** _Поддержать нас на Дзен_** Из-за нехватки топлива давление, удерживавшее звезду от сжатия, падает. Гравитация берет верх, и внешние слои на огромной скорости обрушиваются внутрь. Они врезаются в сверхплотное ядро, отскакивают от него и порождают колоссальную ударную волну, которая разрывает светило на части. Именно в эти короткие секунды выделяется столько энергии, что в космос выбрасываются элементы, из которых потом формируются планеты и, в конечном итоге, мы сами. Как метко заметил британский космолог сэр Мартин Рис: **«Мы — в буквальном смысле пепел давно погасших звезд. Или, если выражаться менее романтично, ядерные отходы того самого топлива, которое когда-то заставляло их светить»**. Но несмотря на то, что человечество наблюдает за такими взрывами еще со времен древнекитайских астрономов, сам механизм «детонатора» остается загадкой. И у современной науки есть весьма специфическая проблема с тем, чтобы эту загадку разгадать. В наши дни оптические и радиотелескопы фиксируют сверхновые ежедневно, но все они происходят в далеких галактиках. Электромагнитное излучение от этих взрывов по пути к Земле рассеивается и поглощается космической пылью и газом. К моменту, когда свет достигает объективов, самые важные данные о том, что именно произошло в недрах звезды за секунды до взрыва, оказываются безнадежно утерянными. Единственный способ заглянуть прямо в «сердце» взрыва — использовать гравитационные волны и нейтрино. В отличие от фотонов, рябь пространства-времени проходит сквозь материю беспрепятственно. Проблема лишь в том, что поймать ее крайне сложно. За последнее десятилетие коллаборация обсерваторий LIGO, Virgo и KAGRA зафиксировала **390 гравитационных сигналов**. Абсолютно все они исходили от слияний черных дыр или нейтронных звезд. Ни одного сигнала от сверхновой ученые не получили. Дело в масштабах. Столкновение двух черных дыр настолько сильно искажает пространство, что детекторы на Земле «слышат» это даже за миллиарды световых лет. Гравитационный всплеск от коллапса ядра сверхновой значительно слабее. Чтобы наши приборы смогли его зафиксировать, звезда должна взорваться буквально на нашем заднем дворе — в пределах Млечного Пути. Тут в игру вступает банальная статистика. По расчетам астрофизиков, в галактике размером с Млечный Путь сверхновые с коллапсирующим ядром должны вспыхивать примерно один раз в столетие. Последняя такая сверхновая в нашей галактике, за которой люди могли наблюдать достоверно, — это сверхновая Кеплера. Она вспыхнула в 1604 году. Технически, Млечный Путь задолжал нам как минимум три зрелищных космических взрыва. Очередной коллапс может произойти когда угодно — завтра, через неделю или прямо сейчас, пока вы читаете этот текст. Доктор И Шуэн Кристин Ли (Yi Shuen Christine Lee) и ее коллеги из Мельбурнского университета, работающие в рамках австралийского центра астрофизики OzGrav, решили не ждать у моря погоды и заранее подготовить алгоритмы для анализа будущего сигнала. Теоретические симуляции показывают, что ключом к разгадке станут низкочастотные гравитационные волны. Исследователи выяснили, что наличие или отсутствие сигнатур на частотах **ниже 250 Герц** прямо перед моментом взрыва укажет на то, какие именно физические процессы шли в ядре. Ученым нужно быть уверенными, что когда сигнал наконец ударит по зеркалам интерферометров на Земле, программное обеспечение сможет мгновенно отделить нужные паттерны от фонового шума. Характеристика источника| Слияние черных дыр / нейтронных звезд| Коллапс ядра сверхновой (CCSN) ---|---|--- **Количество пойманных сигналов**| 390 событий| 0 событий **Мощность гравитационной волны**| Экстремально высокая| Относительно слабая **Рабочая дистанция детекторов**| Миллиарды световых лет| Только Млечный Путь и его окрестности **Научная ценность**| Проверка ОТО, свойства мертвых объектов| Механика взрыва, происхождение элементов ### FAQ: Часто задаваемые вопросы **Что такое гравитационная волна?** Это физическая рябь в ткани пространства-времени, предсказанная Альбертом Эйнштейном. Она возникает при движении массивных объектов с ускорением, подобно кругам на воде от брошенного камня. **Сможет ли взрыв близкой сверхновой уничтожить Землю?** Если сверхновая вспыхнет на расстоянии менее 50 световых лет от нас, ее излучение действительно способно уничтожить озоновый слой планеты. К счастью, в таком радиусе нет массивных звезд-кандидатов, готовых взорваться в обозримом будущем. Те, что могут вспыхнуть (например, Бетельгейзе), находятся на безопасном расстоянии. **Почему мы уверены, что сверхновая излучает гравитационные волны?** Взрыв массивной звезды происходит асимметрично. Колоссальные массы вещества перемещаются с околосветовой скоростью неравномерно, что, согласно Общей теории относительности, неизбежно должно генерировать гравитационные возмущения. * * * Физика уже преодолела технологический барьер: на Земле построены многокилометровые детекторы стоимостью в миллиарды долларов, способные замерять смещения в тысячные доли протона. Код для расшифровки сигнала готов. Теперь дело за малым — нам просто нужно, чтобы Вселенная оказала любезность и взорвала подходящую звезду где-нибудь неподалеку. _Источники:_ 1. Dr Yi Shuen Christine Lee. _Exploding stars are trying to talk to us through gravitational waves_. Pursuit (University of Melbourne). Опубликовано 12 июня 2026 года. **_Поддержать нас на Boosty_** ** _Поддержать нас на Дзен_** Читайте также: Антарктические льды записали маршрут Земли сквозь пыль от взрыва сверхновой Поделиться

On a clear night beneath a dark sky, the stars above can seem timeless. The faint band of the Milky Way stretches across the heavens much as it has for countless generations. To human eyes, the universe appears calm, permanent, and unchanging. Yet this impression is an illusion. The cosmos is constantly evolving. Stars are born and die. Black holes grow. Clouds of gas collapse into brilliant stellar nurseries. Entire galaxies collide, merge, and transform. Over immense spans of time, structures that appear eternal undergo dramatic changes. Galaxies, the giant cities of stars that fill the universe, are not fixed objects frozen in time. They have histories, life cycles, and futures. A galaxy seen today may look completely different billions of years from now. Its shape may change. Its stellar population may age. Its star-forming regions may fade. It may absorb smaller galaxies or merge with larger neighbors. The study of these long-term transformations is known as galactic evolution. Galactic evolution seeks to answer one of astronomy’s most fascinating questions: How do galaxies change over billions of years? The answer reveals a universe far more dynamic and dramatic than most people imagine. It is a story of growth, destruction, renewal, and transformation on scales almost beyond comprehension. ## Understanding What a Galaxy Is Before exploring galactic evolution, it is important to understand what galaxies are. A galaxy is a vast gravitationally bound collection of stars, gas, dust, dark matter, planets, black holes, and other cosmic material. Galaxies come in many sizes and shapes. Some contain only a few million stars. Others contain trillions. Our home galaxy, the Milky Way, contains hundreds of billions of stars spread across a structure more than 100,000 light-years wide. Galaxies are among the fundamental building blocks of the universe. Nearly every star visible in the night sky belongs to a galaxy, and beyond our own galaxy lie hundreds of billions more. These enormous systems may seem permanent, but they are constantly changing through a variety of physical processes. Galactic evolution is the study of those changes. ## The Universe Was Not Always Filled with Galaxies One of the most remarkable discoveries in modern astronomy is that galaxies had a beginning. Shortly after the Big Bang, the universe looked nothing like it does today. There were no galaxies. There were no stars. There were no planets. The early universe consisted primarily of hot particles, radiation, and expanding space. As the universe expanded and cooled, matter gradually began to collect under the influence of gravity. Tiny variations in density became increasingly important. Regions containing slightly more matter than average exerted a stronger gravitational pull. Over millions and billions of years, these dense regions attracted more material. Eventually, the first galactic structures began to emerge. Galactic evolution therefore begins with the birth of galaxies themselves. ## The Role of Dark Matter To understand how galaxies form and evolve, astronomers must first consider dark matter. Dark matter remains one of the greatest mysteries in science. Unlike ordinary matter, dark matter does not emit, absorb, or reflect light. It is invisible to telescopes. Yet its gravitational influence is enormous. Evidence suggests that dark matter makes up most of the matter in the universe. Shortly after the Big Bang, dark matter began clumping together under gravity. These clumps formed enormous structures known as dark matter halos. Ordinary matter, primarily hydrogen and helium gas, fell into these halos. As gas accumulated, galaxies began taking shape. In many ways, dark matter provided the invisible scaffolding upon which galaxies were built. Without it, galactic evolution might have unfolded very differently. ## The Birth of the First Galaxies The first galaxies were very different from the large, majestic systems we see today. They were generally smaller, less organized, and more chaotic. The early universe was crowded with gas and matter. Interactions between young galaxies occurred frequently. Stars formed rapidly within dense clouds of hydrogen gas. These first generations of stars played a crucial role in shaping galactic evolution. Many were far more massive than the Sun. Because massive stars consume their fuel quickly, they lived short lives before exploding as supernovae. These explosions enriched galaxies with heavier elements such as carbon, oxygen, silicon, and iron. Over time, these elements became the building blocks of future stars, planets, and eventually life itself. The earliest galaxies were not merely collections of stars. They were cosmic factories transforming the chemical makeup of the universe. ## Gravity: The Architect of Galactic Evolution Gravity is the primary force driving galactic evolution. Every major stage of a galaxy’s life involves gravity in some way. Gravity pulls gas together to form stars. Gravity holds galaxies together. Gravity causes galaxies to interact and merge. Gravity shapes the large-scale structure of the universe. Without gravity, matter would remain scattered throughout space. Stars would not form. Galaxies would not exist. Throughout billions of years, gravity continuously influences the growth and transformation of galactic systems. In many ways, galactic evolution is the story of gravity operating on the grandest scales imaginable. ## Star Formation and Galactic Growth One of the most important processes in galactic evolution is star formation. Young galaxies often contain vast reservoirs of cold hydrogen gas. Under the influence of gravity, regions within these clouds collapse inward. As they become denser, temperatures rise. Eventually, nuclear fusion ignites, and a new star is born. When star formation occurs across an entire galaxy, it can dramatically alter the galaxy’s appearance. Young stars are typically hot, bright, and blue. Galaxies rich in newly formed stars often shine with a bluish color. These galaxies appear active and vibrant. In contrast, galaxies where star formation has largely ceased tend to contain older, cooler stars. These systems often appear yellowish or reddish. The rate at which stars form is one of the most important factors determining a galaxy’s evolution. ## The Life Cycle of Stars and Their Influence on Galaxies Galactic evolution is deeply connected to stellar evolution. Stars are not permanent. They are born, live for millions or billions of years, and eventually die. As stars age, they influence their host galaxies in several ways. Young massive stars emit powerful radiation and stellar winds that shape surrounding gas clouds. When massive stars explode as supernovae, they inject enormous amounts of energy into their environments. These explosions distribute heavy elements throughout the galaxy. Future generations of stars form from this enriched material. As a result, galaxies gradually become chemically more complex over time. The carbon in living organisms, the oxygen we breathe, and the iron in our blood were all forged within ancient stars. Galactic evolution and stellar evolution are inseparable parts of the same cosmic story. ## Why Galaxies Have Different Shapes One of the most visible outcomes of galactic evolution is the wide variety of galaxy shapes. Some galaxies are spirals. Others are elliptical. Still others are irregular. These shapes are not random. They reflect a galaxy’s history. Spiral galaxies typically contain rotating disks rich in gas and active star formation. Elliptical galaxies often contain older stars and relatively little gas. Irregular galaxies frequently show signs of past interactions or ongoing disturbances. The shape of a galaxy can reveal clues about billions of years of evolution. Astronomers often describe galactic appearance as a kind of fossil record. By studying a galaxy’s structure, scientists can reconstruct aspects of its past. ## Galactic Collisions: Cosmic Encounters One of the most dramatic drivers of galactic evolution is collision. Although galaxies are separated by enormous distances, collisions are surprisingly common on cosmic timescales. Galaxies move through space under the influence of gravity. Over billions of years, some inevitably approach one another. When galaxies collide, the results can be spectacular. Contrary to what many imagine, stars rarely crash directly into each other. The distances between stars are simply too large. Instead, gravity reshapes the galaxies involved. Spiral arms may stretch outward. Gas clouds may compress. Star formation may accelerate dramatically. The galaxies may eventually merge into a completely new system. These interactions play a central role in galactic evolution. ## Galaxy Mergers and Transformation Some collisions lead to mergers. A merger occurs when two galaxies combine into a single larger galaxy. This process can take hundreds of millions or even billions of years. During a merger, gravitational forces pull stars and gas into new arrangements. The original structures often disappear. Two spiral galaxies may merge to create a giant elliptical galaxy. Gas clouds collide and trigger intense bursts of star formation. Central black holes may move toward one another and eventually merge. These events profoundly alter a galaxy’s future. Many of the largest galaxies in the universe were built through repeated mergers over cosmic history. In a sense, galaxies grow by consuming and absorbing other galaxies. ## The Growth of Supermassive Black Holes At the centers of most large galaxies reside supermassive black holes. These objects contain millions or even billions of times the mass of the Sun. The relationship between galaxies and their central black holes is one of the most intriguing areas of modern astronomy. As galaxies evolve, their black holes often grow as well. Gas falling toward the black hole can form an extremely hot accretion disk. This process releases enormous amounts of energy. In some cases, the central region becomes an active galactic nucleus. The energy produced can influence the entire galaxy. Powerful outflows may heat surrounding gas and reduce future star formation. Thus, black holes are not merely passive occupants of galaxies. They actively participate in galactic evolution. ## Starburst Galaxies Sometimes galaxies experience periods of extraordinarily intense star formation. These episodes are known as starbursts. During a starburst, stars form at rates many times greater than normal. Galaxy collisions often trigger these events. When gas clouds collide and compress, they create ideal conditions for stellar birth. A starburst galaxy may produce thousands of new stars in a relatively short period. Such episodes dramatically affect galactic evolution. They consume large amounts of gas. They produce powerful stellar winds. They generate numerous supernova explosions. Although starbursts are temporary, their effects can shape a galaxy for billions of years. ## The Importance of Gas Gas is the fuel that powers star formation. A galaxy rich in cold hydrogen gas can continue producing stars for long periods. A galaxy that loses its gas faces a different future. Without fresh material, star formation gradually declines. Existing stars continue aging, but few new stars replace them. Over time, the galaxy becomes dominated by older stellar populations. Astronomers often describe gas as the lifeblood of a galaxy. The amount, distribution, and movement of gas strongly influence galactic evolution. Understanding how galaxies gain and lose gas remains a major focus of research. ## Galactic Cannibalism The phrase “galactic cannibalism” may sound dramatic, but it accurately describes a common cosmic process. Large galaxies frequently absorb smaller companions. As a dwarf galaxy approaches a larger galaxy, tidal forces begin pulling it apart. Its stars may spread into long streams. Eventually, much of the smaller galaxy becomes incorporated into the larger system. The Milky Way itself has grown partly through this process. Astronomers have discovered evidence that our galaxy has absorbed numerous smaller galaxies throughout its history. Galactic cannibalism contributes significantly to galactic growth and evolution. ## The Evolution of Spiral Galaxies Spiral galaxies are among the most visually striking structures in the universe. Their graceful arms contain abundant gas, dust, and young stars. Over time, however, spiral galaxies evolve. Star formation gradually consumes available gas. Interactions with neighboring galaxies may distort spiral patterns. Mergers can completely transform their structure. The future of a spiral galaxy depends largely on its environment. Some may retain their spiral appearance for billions of years. Others may eventually become elliptical galaxies following major mergers. Spiral galaxies are not permanent forms. They are stages within larger evolutionary journeys. ## The Evolution of Elliptical Galaxies Elliptical galaxies often represent a later stage of galactic evolution. These systems generally contain older stars and relatively little gas. Because they lack significant star-forming material, new stars form only rarely. Elliptical galaxies tend to appear smooth and reddish. Many are believed to have formed through mergers involving spiral galaxies. After repeated collisions, organized structures disappear. The resulting galaxy becomes dominated by random stellar motions rather than orderly rotation. Elliptical galaxies may continue evolving through additional mergers, but their overall appearance often changes more slowly than younger systems. ## Irregular Galaxies and Cosmic Youth Irregular galaxies play a unique role in galactic evolution. These systems lack the clear structures seen in spirals and ellipticals. Many irregular galaxies are relatively small and rich in gas. Their active star formation makes them valuable laboratories for studying galactic growth. In the distant universe, astronomers observe many young galaxies that appear irregular. This suggests that irregular structures were more common during earlier cosmic epochs. Some irregular galaxies may eventually evolve into more organized forms. Others remain chaotic due to ongoing interactions. Their diversity highlights the complexity of galactic evolution. ## Chemical Evolution Within Galaxies Galaxies do not evolve only in appearance. Their chemical composition changes as well. The earliest galaxies consisted mainly of hydrogen and helium. Heavier elements were rare. As stars formed and died, they created new elements through nuclear fusion. Supernova explosions distributed these materials throughout galaxies. Future generations of stars incorporated the enriched matter. Over billions of years, galaxies became increasingly rich in heavy elements. This chemical evolution has profound consequences. Planets require heavy elements. Life depends on elements such as carbon, oxygen, nitrogen, and phosphorus. The evolution of galaxies therefore helped create the conditions necessary for life to emerge. ## Looking Back Through Time One of astronomy’s greatest advantages is its ability to observe the past. Light travels at a finite speed. When we observe distant galaxies, we see them as they existed long ago. A galaxy one billion light-years away appears as it was one billion years in the past. A galaxy ten billion light-years away reveals conditions from ten billion years ago. Powerful telescopes allow astronomers to study galactic evolution directly by observing galaxies at different stages of cosmic history. This ability is like having access to a vast historical archive stretching across billions of years. Every distant galaxy provides a glimpse into the universe’s past. ## The Future of the Milky Way Galactic evolution is not merely something that happened long ago. It continues today. The Milky Way remains an active galaxy. Stars continue forming within its spiral arms. It continues interacting with nearby dwarf galaxies. Its central black hole continues influencing the galactic environment. One of the most significant future events involves the neighboring Andromeda Galaxy. The Milky Way and Andromeda are moving toward each other. In roughly four to five billion years, they are expected to begin merging. The collision will transform both galaxies. Their shapes will change dramatically. New bursts of star formation may occur. Eventually, they will likely form a single larger galaxy. This future merger demonstrates that galactic evolution remains an ongoing process. ## The Role of Environment Not all galaxies evolve in the same way. Their surroundings matter greatly. Galaxies located in dense clusters experience frequent interactions. Those in more isolated regions may evolve more quietly. Cluster environments can strip gas from galaxies. Repeated encounters may alter structures and suppress star formation. Isolated galaxies often retain gas longer and continue producing stars for extended periods. Environment acts as a powerful influence on galactic destiny. Two galaxies born under similar conditions may follow very different evolutionary paths depending on where they reside. ## The Ultimate Fate of Galaxies What happens to galaxies over the longest timescales? Current evidence suggests many galaxies will eventually exhaust much of their star-forming gas. As star formation declines, galaxies become increasingly dominated by aging stars. The brightest, hottest stars die first. Remaining stars become older and dimmer. Over trillions of years, galaxies may evolve into quieter and less active systems. Yet even then, gravitational interactions and mergers will continue shaping cosmic structures. Galactic evolution never truly stops. It simply unfolds at different rates and in different forms. ## Why Galactic Evolution Matters Understanding galactic evolution helps answer some of humanity’s most profound questions. How did galaxies form? Why do they look different? How did the elements necessary for life arise? What is the future of the Milky Way? How has the universe changed since the Big Bang? Galactic evolution connects these questions into a single narrative. It reveals that galaxies are not static collections of stars. They are dynamic systems shaped by gravity, star formation, chemical enrichment, black holes, collisions, and cosmic time. Every galaxy visible through a telescope carries a unique history written across billions of years. ## Conclusion Galactic evolution is the story of how galaxies form, grow, interact, and transform over cosmic time. Beginning with tiny fluctuations in the early universe, galaxies emerged within vast halos of dark matter and gradually developed into the diverse structures we observe today. Through star formation, supernova explosions, gas flows, black hole activity, collisions, and mergers, galaxies continuously change their appearance and composition. The spiral galaxies, elliptical giants, and irregular systems scattered across the cosmos are not permanent creations. They are snapshots of ongoing journeys that span billions of years. Every galaxy possesses a past shaped by countless events and a future still unfolding. By studying galactic evolution, astronomers are not simply examining distant objects in space. They are uncovering the history of the universe itself. They are learning how stars, planets, and the elements of life came to exist. They are discovering how the Milky Way became our cosmic home and how it will continue changing long after humanity is gone. In the end, galactic evolution reminds us that the universe is not a static masterpiece hanging in space. It is a living, evolving cosmos where change is constant, creation never truly ends, and every galaxy is part of an extraordinary story still being written across the vastness of time.

We present multi-wavelength photometric and optical spectroscopic observations of the long-lived interacting supernova SN 2019vxm, spanning more than two years after the explosion. SN 2019vxm is a slowly rising (rise time ~ 45.9 days in the R-band), slowly declining supernova reaching an R-band peak absolute magnitude of ~-20.3 mag. The SN light curve post-maximum shows a shallow decline, followed by a secondary, steeper decline in the optical (0.01 mag/day), with late-time IR brightening. The total radiated luminosity is 5x10^50 erg, placing it among the energetic class of its type. We estimated a CSM mass of 3-8 M_sun through light-curve modeling (independent of the CSM density profile) and by comparison with theoretical models. We estimate a minimum ejecta mass of ~ 3.88 M_sun from the broad H-alpha component, consistent with the ejecta mass obtained from the light curve models. The solely interaction-dominated initial epochs are later accompanied by photon-scattering signatures, leading to asymmetric line profiles with symmetric wings. The late phase, characterized by enhanced brightness at longer wavelengths and a stronger asymmetric line profile with the red side flux strongly suppressed, indicates the influence of pre-existing or newly formed dust with temperatures ~ 1500 K at ~4x10^16 cm. Even in the late phases, no nebular lines are present in the spectra, indicating dense or obscured ejecta.

The young neutron star 1E 1207.4–5209 is the central compact object of its supernova remnant. Using the sensitive MeerKAT array, it has now been detected at radio wavelengths, suggesting that other central compact objects might also be radio pulsars.

On a clear, dark night, the sky can appear filled with countless stars scattered randomly across the heavens. To the naked eye, they often seem like isolated points of light separated by vast stretches of darkness. Yet this impression is somewhat misleading. Many stars are not alone. They belong to larger families connected by a powerful force that shapes the entire universe: gravity. Among the most beautiful and fascinating of these stellar families are star clusters. These remarkable gatherings contain dozens, hundreds, thousands, or even millions of stars that formed together and remain linked through their mutual gravitational attraction. They are cosmic communities, born from the same giant clouds of gas and dust, sharing a common origin story that stretches back millions or billions of years. Star clusters are among the most important objects in astronomy. They help scientists understand how stars are born, how they evolve, and how galaxies change over time. They serve as natural laboratories where astronomers can study stars of different masses and ages under similar conditions. Some clusters are relatively young, still glowing with the energy of recent star formation. Others are ancient survivors from the earliest chapters of our galaxy’s history. The Milky Way contains hundreds of known star clusters and likely many more waiting to be discovered. Together, they provide a living record of our galaxy’s past and offer clues about its future. To understand star clusters is to understand one of the universe’s most beautiful expressions of cosmic family. ## What Exactly Is a Star Cluster? A star cluster is a group of stars that are physically associated with one another through gravity and that usually share a common origin. Unlike stars that merely appear close together from Earth’s perspective, stars in a true cluster are actually located near one another in space. Most of them formed from the same giant molecular cloud—a vast region of cold gas and dust where star formation takes place. Because these stars were born from the same cloud, they often have similar ages and chemical compositions. This shared heritage makes star clusters especially valuable to astronomers. Imagine a family reunion where everyone shares common ancestors. Even though family members may have different personalities, appearances, and life experiences, they remain connected through their origins. In a similar way, stars within a cluster can vary greatly in size, temperature, brightness, and lifespan, yet they remain related through their common birth environment. Gravity acts as the glue that holds these stellar families together. Without gravity, the stars would drift apart into the galaxy and lose their identity as a cluster. ## The Birthplace of Stars To understand star clusters, we must first understand where stars come from. Stars are born inside enormous clouds of gas and dust called molecular clouds. These clouds are among the coldest regions in the galaxy, with temperatures low enough for molecules to exist. Despite their peaceful appearance, molecular clouds are dynamic environments. Turbulence, shock waves from nearby supernova explosions, and gravitational forces constantly influence their structure. Eventually, certain regions within a cloud become dense enough for gravity to take over. As gravity pulls material inward, the region begins collapsing. The collapsing gas becomes hotter and denser until young stars start to form. But stars rarely form one at a time. Instead, a single cloud often produces large numbers of stars simultaneously. Entire groups of stars emerge from the same stellar nursery. This is why star clusters exist. They are the natural outcome of the star formation process. ## Gravity: The Force That Creates Families Gravity is one of the four fundamental forces of nature, and it plays the central role in the existence of star clusters. Every star exerts a gravitational pull on every other star in the cluster. Although the gravitational attraction between individual stars may be relatively weak because of their great separations, the combined gravitational influence of hundreds or thousands of stars creates a stable system. This mutual attraction prevents the cluster from immediately dispersing into the galaxy. In many ways, gravity acts like an invisible web connecting every member of the cluster. Each star moves through space while simultaneously responding to the gravitational influence of its neighbors. The result is a dynamic, constantly evolving system that can survive for millions or even billions of years. ## Why Star Clusters Matter At first glance, star clusters might seem like merely beautiful collections of stars. In reality, they are among the most important tools in astronomy. One reason is that stars within a cluster generally formed at roughly the same time. This provides astronomers with a unique opportunity. When scientists study isolated stars, determining their exact ages can be difficult. But in a cluster, researchers know that most stars share a common birth date. This allows astronomers to compare stars of different masses while holding age relatively constant. Star clusters therefore function as natural laboratories for studying stellar evolution. By observing cluster stars, scientists can test theories about how stars live and die. These observations have helped shape much of modern astrophysics. ## The Two Main Types of Star Clusters Although star clusters come in many forms, astronomers generally divide them into two major categories. The first category is open clusters. The second category is globular clusters. These two groups differ dramatically in age, size, structure, appearance, and history. Together, they reveal different chapters in the story of the Milky Way. ## Open Clusters: Young Families of Stars Open clusters are relatively loose collections of stars. They typically contain anywhere from a few dozen to several thousand stars. Unlike tightly packed globular clusters, open clusters have an irregular appearance. Their stars are spread over larger areas, and the clusters often lack a clearly defined shape. Most open clusters are young by astronomical standards. Some are only a few million years old. Others may survive for several hundred million years before gradually dispersing. Because they are young, open clusters often contain bright blue stars. These massive stars burn hot and fast, shining brilliantly but living relatively short lives. When we observe open clusters, we are often witnessing stellar youth. ## The Pleiades: One of the Most Famous Open Clusters Perhaps the most famous open cluster in the night sky is the Pleiades. Also known as the Seven Sisters, the Pleiades has been observed by humans for thousands of years. Visible without a telescope, it appears as a small group of bright stars clustered together. Ancient cultures around the world incorporated the Pleiades into myths, calendars, and navigation systems. Modern astronomy reveals that the cluster contains hundreds of stars, although only a handful are easily visible to the naked eye. The Pleiades formed roughly 100 million years ago, making it relatively young. It provides a stunning example of an open cluster still holding together despite the forces trying to pull it apart. ## The Hyades and Nearby Stellar Neighbors Another important open cluster is the Hyades. The Hyades is the closest major open cluster to Earth. Its stars form a distinctive V-shaped pattern in the constellation Taurus. Because of its proximity, the Hyades has played a crucial role in astronomical research. Scientists have used it to improve distance measurements, study stellar evolution, and test theoretical models. Its relatively close location allows astronomers to examine individual stars with exceptional detail. ## Why Open Clusters Eventually Disappear Despite their beauty, open clusters are usually temporary structures. Several factors gradually pull them apart. Stars within the cluster constantly interact gravitationally with one another. These interactions can alter stellar orbits and sometimes eject stars from the cluster entirely. Passing molecular clouds can also disturb the cluster. The gravitational influence of the Milky Way itself contributes to the process. Over time, more and more stars escape. Eventually, the cluster loses its identity. Its former members continue orbiting the galaxy independently. Many stars currently scattered throughout the Milky Way may once have belonged to ancient open clusters that no longer exist. In fact, our own Sun likely formed within a cluster billions of years ago before becoming separated from its stellar siblings. ## Globular Clusters: Ancient Giants If open clusters are youthful families, globular clusters are ancient dynasties. Globular clusters are among the oldest structures in the Milky Way. Many formed more than 10 billion years ago, making them nearly as old as the galaxy itself. These clusters contain enormous numbers of stars. Some host hundreds of thousands of stars. Others contain more than a million. Unlike open clusters, globular clusters are tightly packed and roughly spherical. Near their centers, stars can be extraordinarily crowded. The night sky inside a globular cluster would look astonishingly different from what we see on Earth. Thousands of bright stars would dominate the heavens. ## The Great Cluster in Hercules One of the most famous globular clusters is Messier 13. Often called the Great Hercules Cluster, it is visible through small telescopes and binoculars. Located tens of thousands of light-years away, it contains hundreds of thousands of stars packed into a relatively compact volume of space. Its dazzling appearance has fascinated astronomers for centuries. When viewed through larger telescopes, individual stars begin to emerge from what initially appears to be a fuzzy ball of light. Messier 13 offers a glimpse into one of the oldest stellar populations in our galaxy. ## Ancient Survivors from the Early Universe Globular clusters are valuable because they preserve information about the early history of the Milky Way. Most of their stars formed long before Earth existed. Many originated when the galaxy itself was still taking shape. Because these clusters are so old, they contain relatively few heavy elements. In astronomy, elements heavier than hydrogen and helium are produced inside stars and distributed through space when stars die. The earliest generations of stars formed before many heavy elements existed. Globular cluster stars therefore act as fossils from an earlier cosmic era. Studying them allows scientists to investigate conditions that existed billions of years ago. ## Where Star Clusters Live in the Milky Way Open and globular clusters occupy different regions of the galaxy. Open clusters are mostly found in the Milky Way’s disk. This is the flattened region where gas, dust, and ongoing star formation are concentrated. Their presence there reflects their youthful origins. Since stars continue forming in the galactic disk, new open clusters constantly appear. Globular clusters occupy a different environment. Most reside in the galactic halo, a vast spherical region surrounding the Milky Way. They orbit far above and below the galactic plane. This distribution supports the idea that globular clusters formed during the earliest stages of galactic evolution. Their locations provide important clues about how the Milky Way assembled itself over time. ## How Astronomers Identify Cluster Members One challenge in studying star clusters involves determining which stars truly belong to the cluster. Not every star seen in the same direction is necessarily a member. Some stars may simply lie along the same line of sight. Modern astronomy uses several techniques to solve this problem. Astronomers measure stellar motions, distances, and chemical compositions. Stars belonging to the same cluster generally move together through space. They often share similar chemical fingerprints as well. Data from missions such as Gaia have revolutionized this process. Gaia has mapped the positions and motions of billions of stars, allowing researchers to identify cluster members with unprecedented precision. ## The Life Cycle of Stars Inside Clusters One of the greatest advantages of studying clusters is that they reveal different stages of stellar evolution. Stars are born with varying masses. Mass determines nearly everything about a star’s future. Massive stars burn fuel rapidly and die young. Smaller stars burn fuel slowly and can survive for billions or even trillions of years. Because cluster stars formed together, differences among them primarily reflect differences in mass rather than age. This makes clusters ideal for testing theories of stellar evolution. Astronomers can observe how stars of different masses change over time while knowing they originated from the same environment. ## Star Cluster Colors and What They Mean The colors of cluster stars tell important stories. Blue stars are typically hot and massive. White stars are somewhat cooler. Yellow stars resemble our Sun. Orange and red stars are cooler still. A young open cluster often contains many bright blue stars. These stars have not yet exhausted their nuclear fuel. Older clusters look different. Their massive blue stars have already died. As a result, older clusters are dominated by redder stars. The overall color of a cluster therefore provides clues about its age. In some sense, astronomers can estimate a cluster’s age simply by examining the stars that remain alive. ## Binary Stars and Stellar Interactions Many stars exist in pairs. These systems are called binary stars. Clusters contain large numbers of binary systems. In dense environments, especially globular clusters, stars can interact in fascinating ways. Close encounters may alter stellar orbits. Binary stars can exchange material. Rare collisions can occur. These interactions create unusual objects that are rarely seen elsewhere. Some stars appear younger than they should. Others become exceptionally bright. Clusters therefore serve as natural laboratories for studying complex gravitational dynamics. ## The Mystery of Blue Stragglers Among the strangest cluster stars are blue stragglers. These stars appear younger than the rest of the cluster. In an old cluster, massive blue stars should have died long ago. Yet blue stragglers remain. Their existence puzzled astronomers for decades. The most likely explanation involves stellar interactions. Some blue stragglers may form when two smaller stars merge. Others may gain mass from a companion star. By becoming more massive, they effectively receive a second chance at stellar youth. Blue stragglers remind us that star clusters are not static systems. They continue evolving long after their formation. ## Star Clusters Beyond the Milky Way Although the Milky Way contains many clusters, it is far from unique. Other galaxies possess their own stellar families. Large galaxies often host thousands of globular clusters. Some dwarf galaxies contain only a few. Observing clusters in distant galaxies helps astronomers compare galactic histories across the universe. These observations reveal that star clusters are a common outcome of galaxy formation. They are not rare exceptions. They are a fundamental part of the cosmic landscape. ## Could Planets Exist in Star Clusters? A fascinating question concerns planets. Can planetary systems form within star clusters? The answer appears to be yes. Astronomers have discovered planets associated with cluster stars. However, cluster environments can be challenging. Nearby stars may gravitationally disturb planetary systems. Radiation from massive stars can affect young planets. Despite these obstacles, planets clearly can exist within clusters. This raises intriguing possibilities. Some worlds may orbit stars surrounded by hundreds or thousands of neighboring suns visible in their skies. The nightscapes on such planets would be dramatically different from Earth’s. ## The Future of the Sun’s Lost Family Evidence suggests that the Sun formed approximately 4.6 billion years ago inside a cluster. The original cluster likely contained hundreds or perhaps thousands of stars. Over time, gravitational interactions dispersed the group throughout the Milky Way. Today, those stellar siblings are scattered across the galaxy. Astronomers continue searching for them. By comparing stellar ages, chemical compositions, and motions, researchers hope to identify stars that shared the Sun’s birthplace. Finding these siblings would provide valuable insights into our solar system’s origins. ## Star Clusters and the Search for Galactic History Star clusters function as historical records. Each cluster preserves information about the conditions that existed when it formed. By studying clusters of different ages, astronomers can reconstruct the Milky Way’s past. Young clusters reveal current star formation. Intermediate-age clusters show how stellar populations evolve. Ancient globular clusters offer glimpses of the galaxy’s earliest epochs. Together, they form a timeline stretching across billions of years. Without star clusters, much of the Milky Way’s history would remain hidden. ## Modern Telescopes and New Discoveries Advances in technology continue transforming cluster research. Powerful telescopes can now resolve individual stars in distant clusters. Space observatories avoid atmospheric distortions and provide clearer views. Large surveys generate enormous datasets that reveal previously unknown structures. Artificial intelligence and advanced computer simulations help astronomers analyze complex stellar systems. As a result, new clusters are still being discovered. Old assumptions are being revised. Questions once thought impossible to answer are gradually yielding to investigation. The study of star clusters remains one of astronomy’s most active fields. ## The Beauty of Cosmic Families Beyond their scientific importance, star clusters possess extraordinary beauty. They remind us that stars are not always solitary wanderers. Many begin life together. They share origins, environments, and histories. Some remain bound for billions of years. Others slowly drift apart, carrying memories of their common birthplace across the galaxy. When we look at a cluster through a telescope, we are seeing more than a collection of stars. We are witnessing relationships forged by gravity. We are observing families on a cosmic scale. These stellar communities reveal that even in the vast emptiness of space, connection matters. ## Conclusion Star clusters are among the most remarkable structures in the universe. They are groups of stars born from the same cloud of gas and dust and held together by gravity, forming true stellar families within the Milky Way. From the youthful brilliance of open clusters to the ancient grandeur of globular clusters, they showcase the many stages of stellar life and galactic evolution. For astronomers, star clusters are invaluable laboratories. They provide insights into how stars form, evolve, interact, and die. They preserve records of the Milky Way’s history, helping scientists reconstruct events that occurred billions of years ago. Some clusters contain stars that have existed since the earliest eras of our galaxy, while others are still emerging from their stellar nurseries today. Yet star clusters offer more than scientific knowledge. They inspire wonder. They reveal that even across unimaginable distances, gravity can bind countless stars into enduring communities. They show that the universe is not merely a collection of isolated objects but a place filled with relationships, histories, and shared origins. The next time you gaze at the night sky and spot a sparkling cluster of stars, remember that you are looking at a family. Those stars were born together, journey together, and tell a story that stretches across millions or billions of years. In their light, we glimpse not only the workings of gravity but also the deep interconnectedness of the cosmos itself.

On a clear night, far from city lights, the sky becomes a window into something vast and humbling. Thousands of stars shimmer overhead, planets wander silently among them, and the pale band of the Milky Way stretches across the darkness like a cosmic river. It is easy to feel small beneath such an immense sky. Yet among all those distant wonders, one region of space is especially important to us. It is our home. It is the place where Earth exists, where life emerged, and where humanity first began to ask questions about the universe. This place is the Solar System. The Solar System is much more than a collection of planets orbiting the Sun. It is a dynamic, interconnected cosmic neighborhood filled with worlds of astonishing variety. There are rocky planets scorched by heat, giant worlds wrapped in storms larger than Earth, icy moons hiding underground oceans, countless asteroids drifting through space, and comets carrying ancient material from the dawn of the universe. For centuries, people believed Earth stood at the center of everything. Today, we know our planet is just one small world orbiting an ordinary star in a galaxy containing hundreds of billions of stars. Yet the Solar System remains extraordinary because it is the only place we know that harbors life. Understanding the Solar System is not simply about learning where planets are located. It is about discovering how gravity shapes cosmic architecture, how worlds form and evolve, and how our own existence is connected to events that began billions of years ago. ## What Exactly Is the Solar System? The Solar System consists of the Sun and everything bound to it by gravity. This includes the eight major planets, their moons, dwarf planets, asteroids, comets, meteoroids, dust, gas, and countless smaller objects. All these bodies travel through space under the influence of the Sun’s immense gravitational pull. The word “solar” comes from the Latin word _sol_ , meaning Sun. The Solar System is therefore literally the system of objects associated with the Sun. At its heart lies the Sun itself, containing more than 99 percent of the Solar System’s total mass. Everything else, from the largest planet to the tiniest grain of cosmic dust, orbits this central star. The Solar System stretches far beyond the orbit of the outermost planet. Its influence extends into distant regions populated by icy objects, reaching trillions of kilometers from the Sun. Although it may seem enormous from our perspective, the Solar System occupies only a tiny corner of the vast Milky Way galaxy. ## The Birth of the Solar System To understand the Solar System, we must travel back approximately 4.6 billion years. At that time, neither Earth nor the Sun existed. Instead, there was a vast cloud of gas and dust floating through space. This cloud, known as a solar nebula, contained mostly hydrogen and helium along with heavier elements created inside earlier generations of stars. Something triggered the cloud to collapse under its own gravity. Perhaps a nearby supernova explosion sent shockwaves through the region. Whatever the cause, the cloud began shrinking and spinning. As it contracted, the material became denser and hotter. Most of the matter gathered in the center, eventually forming the young Sun. The remaining material flattened into a rotating disk surrounding the newborn star. Within this disk, tiny particles collided and stuck together. Over millions of years, these particles grew into larger and larger bodies. Pebbles became rocks. Rocks became planetesimals. Planetesimals became protoplanets. Eventually, the planets we know today emerged. The Solar System was born from a process of accumulation, collision, and gravitational shaping that unfolded over millions of years. ## The Sun: The Heart of the Solar System The Sun dominates every aspect of the Solar System. Without it, the Solar System would not exist. This enormous sphere of hot plasma contains enough mass to hold all the planets in orbit through its gravitational pull. It also provides the light and heat that make life possible on Earth. The Sun is a star, just like countless others scattered across the galaxy. Yet because it is relatively close to us, it appears far brighter than any other star in the sky. Deep within the Sun’s core, temperatures reach about 15 million degrees Celsius. Under these extreme conditions, hydrogen atoms fuse together to form helium. This process, known as nuclear fusion, releases tremendous amounts of energy. Every second, the Sun converts millions of tons of matter into energy. That energy travels outward and eventually reaches Earth as sunlight. The sunlight warming your face today began its journey in the Sun’s core thousands or even hundreds of thousands of years ago before finally escaping into space. ## Gravity: The Invisible Architect If the Sun is the heart of the Solar System, gravity is its architect. Gravity is the force that holds everything together. Every object with mass exerts gravitational attraction on other objects. The more massive an object is, the stronger its gravitational pull. Because the Sun contains so much mass, it dominates the Solar System gravitationally. Planets orbit the Sun because they are constantly falling toward it while simultaneously moving sideways through space. The result is a stable orbit. This delicate balance between motion and gravity creates the elegant dance of celestial bodies. Gravity also governs the movement of moons around planets, rings around giant worlds, and even the trajectories of comets and asteroids. Without gravity, the Solar System would instantly fall apart. ## The Inner Rocky Planets Closest to the Sun are the terrestrial planets, also known as the rocky planets. These worlds are relatively small compared to the giant planets farther out. Mercury is the nearest planet to the Sun. Its surface is covered with craters, resembling Earth’s Moon. Without a substantial atmosphere to regulate temperature, Mercury experiences extreme heat during the day and intense cold at night. Venus is often called Earth’s twin because of its similar size. Yet Venus is a world of hellish conditions. Thick clouds trap heat through a runaway greenhouse effect, making it the hottest planet in the Solar System. Earth is unique among known planets. Liquid water covers much of its surface, and a protective atmosphere supports a rich diversity of life. Mars, the Red Planet, has captivated human imagination for centuries. Ancient river valleys, polar ice caps, and evidence of past water suggest it was once more hospitable than it is today. These four rocky planets formed in the hotter inner region of the early Solar System, where lighter gases could not easily remain. ## The Asteroid Belt Between Mars and Jupiter lies a region known as the asteroid belt. This vast area contains millions of rocky bodies ranging from tiny fragments to objects hundreds of kilometers across. Contrary to popular science fiction portrayals, the asteroid belt is not densely packed. Most asteroids are separated by enormous distances. Scientists believe these objects are leftovers from the Solar System’s formation. Jupiter’s powerful gravity prevented them from combining into a full-sized planet. Asteroids provide valuable clues about the Solar System’s earliest history because many have changed little over billions of years. In a sense, they are time capsules preserving ancient material from the birth of our celestial neighborhood. ## The Giant Planets Beyond the asteroid belt lie the giant planets. These worlds dwarf the rocky planets in both size and mass. Jupiter is the largest planet in the Solar System. More than 1,300 Earths could fit inside it. Its atmosphere contains colorful cloud bands and enormous storms, including the famous Great Red Spot, which has persisted for centuries. Saturn is best known for its magnificent ring system. Although other giant planets also possess rings, Saturn’s are by far the most spectacular. Uranus presents a unique appearance because it rotates on its side. Scientists believe a massive collision early in its history may have tipped it over. Neptune, the outermost major planet, is a world of deep blue color and powerful winds. Some of the fastest winds in the Solar System rage through its atmosphere. These giant planets contain large amounts of hydrogen, helium, and other volatile substances, reflecting the colder conditions in which they formed. ## Why the Planets Orbit in the Same Direction One of the most fascinating features of the Solar System is its overall organization. Most planets orbit the Sun in the same direction. Most also rotate in the same general direction. This pattern is not a coincidence. It reflects the Solar System’s origin within a spinning disk of gas and dust. As the solar nebula collapsed, its rotation became faster due to the conservation of angular momentum. The resulting disk established a preferred direction of motion. The planets inherited this motion as they formed. Today, billions of years later, they still carry the signature of their birth. The Solar System remembers its origins through the motions of its worlds. ## Moons: Worlds Within Worlds Many planets possess natural satellites known as moons. Some moons are small and irregular, resembling captured asteroids. Others are remarkable worlds in their own right. Earth’s Moon has profoundly influenced our planet’s evolution. It stabilizes Earth’s axial tilt and contributes to ocean tides. Jupiter’s moon Io is the most volcanically active body in the Solar System. Europa hides a global ocean beneath an icy crust, making it one of the most promising places to search for extraterrestrial life. Saturn’s moon Titan possesses lakes and rivers, though they are composed of liquid methane and ethane rather than water. Enceladus, another moon of Saturn, ejects plumes of water vapor into space from an underground ocean. These moons demonstrate that planets are not the only interesting destinations in the Solar System. Some may even be more promising for life than certain planets. ## Rings: Nature’s Cosmic Artwork Planetary rings are among the most beautiful structures in the Solar System. Saturn’s rings are the most famous, but Jupiter, Uranus, and Neptune also possess ring systems. These rings consist of countless particles ranging in size from microscopic dust grains to large chunks of ice and rock. Although they appear solid from a distance, they are actually vast collections of orbiting debris. The exact origins of rings vary. Some may be remnants of destroyed moons. Others may consist of material that never formed into larger bodies. Their delicate appearance masks a complex gravitational environment shaped by interactions with nearby moons. ## Comets: Messengers from the Outer Darkness Comets are among the most dramatic objects in the Solar System. Often described as dirty snowballs, they consist of ice, dust, and rocky material. Most comets spend the majority of their existence in distant, cold regions far from the Sun. When a comet approaches the inner Solar System, solar heat causes its ice to vaporize. This creates a glowing coma and sometimes spectacular tails stretching millions of kilometers. For ancient civilizations, comets often seemed like mysterious omens. Today, scientists view them as invaluable relics from the Solar System’s formation. Many comets contain material that has remained largely unchanged for billions of years. Studying them helps researchers understand conditions that existed before the planets formed. ## The Kuiper Belt and Beyond Past Neptune lies a vast region known as the Kuiper Belt. This area contains countless icy bodies left over from the Solar System’s formation. Many dwarf planets reside here, including Pluto. For decades, Pluto was considered the ninth planet. However, discoveries of similar objects beyond Neptune prompted astronomers to redefine what constitutes a planet. In 2006, Pluto was reclassified as a dwarf planet. Although this decision sparked debate, Pluto remains one of the most fascinating worlds ever explored. Far beyond the Kuiper Belt may lie the Oort Cloud, a hypothetical spherical region containing trillions of icy objects. This distant reservoir likely serves as the source of many long-period comets. ## The Mechanics of Planetary Motion Planetary motion follows precise mathematical rules. In the early seventeenth century, astronomers discovered that planets move in elliptical rather than perfectly circular orbits. This insight transformed our understanding of celestial mechanics. Later, the laws of motion and gravity provided a framework for explaining why planets move as they do. Today, scientists can predict planetary positions with extraordinary accuracy. Spacecraft navigate millions of kilometers through space by relying on these principles. The mechanics of planetary motion reveal that the Solar System operates according to consistent natural laws. Its apparent complexity emerges from simple physical principles acting over immense scales. ## Seasons and Planetary Tilts The changing seasons on Earth result from the planet’s axial tilt. As Earth orbits the Sun, different regions receive varying amounts of sunlight throughout the year. This creates the familiar cycle of spring, summer, autumn, and winter. Other planets experience seasons as well. Mars has seasons similar to Earth’s, though they last longer because of its longer year. Uranus experiences particularly extreme seasonal changes because of its unusual tilt. These variations demonstrate how planetary orientation can dramatically influence climate and environmental conditions. ## The Solar Wind and Space Weather The Sun constantly releases streams of charged particles known as the solar wind. These particles flow outward through the Solar System at tremendous speeds. Earth’s magnetic field protects the planet from much of this radiation. When solar particles interact with Earth’s atmosphere, they produce beautiful auroras near the poles. Occasionally, intense solar storms can disrupt satellites, communication systems, and power grids. Understanding space weather has become increasingly important as modern civilization grows more dependent on space-based technology. The Sun is not merely a passive source of light. It actively influences conditions throughout the Solar System. ## Earth’s Place in the Habitable Zone One reason life flourished on Earth is its location relative to the Sun. Earth orbits within a region often called the habitable zone. In this zone, temperatures allow liquid water to exist on a planet’s surface. Water is essential for all known forms of life. If Earth were significantly closer to the Sun, conditions might resemble Venus. If it were much farther away, it could resemble Mars. The habitable zone does not guarantee life, but it provides favorable conditions. Earth’s position highlights how delicate the balance can be between environmental stability and planetary extremes. ## Space Exploration and the Solar System For most of history, the Solar System could only be observed from afar. That changed during the twentieth century. Humanity began sending spacecraft beyond Earth. Robotic explorers visited every major planet. Orbiters mapped distant worlds. Landers touched alien surfaces. Rovers traversed Martian landscapes. Space probes journeyed to the edge of the Solar System. These missions transformed our understanding. Worlds once seen as tiny points of light became complex and diverse places. Each mission revealed new surprises and new mysteries. Space exploration turned the Solar System from a collection of distant objects into a richly detailed cosmic neighborhood. ## Could There Be Life Elsewhere in the Solar System? One of the most exciting questions in science concerns the possibility of life beyond Earth. Several locations within the Solar System are considered promising candidates. Mars shows evidence of ancient environments that may have supported microbial life. Europa contains a vast ocean beneath its icy shell. Enceladus possesses liquid water and organic compounds. Titan hosts complex chemistry unlike anything on Earth. Scientists continue investigating these worlds. No definitive evidence of extraterrestrial life has yet been discovered. However, the search remains one of the most important scientific endeavors of our time. Finding even simple microbial life elsewhere would fundamentally change humanity’s understanding of its place in the universe. ## The Future of the Solar System The Solar System is not static. It continues evolving. Planets shift slowly in their orbits. Asteroids collide. Comets appear and disappear. Stars age. Billions of years from now, the Sun will exhaust much of its hydrogen fuel. It will expand into a red giant star. Its outer layers may engulf Mercury and Venus and possibly affect Earth dramatically. Eventually, the Sun will shed its outer material and leave behind a dense stellar remnant known as a white dwarf. The Solar System will survive, but it will be transformed. The future reminds us that cosmic structures, like living things, experience birth, change, and eventual decline. ## Why the Solar System Matters The Solar System is more than a scientific subject. It is our origin story. Every atom in our bodies was shaped by cosmic processes that occurred long before Earth formed. The planets preserve clues about the early history of the universe. The Sun provides the energy sustaining life. The Moon influences Earth’s environment. Asteroids and comets carry ancient records of planetary formation. Studying the Solar System helps us understand where we came from and where we might go. It connects everyday life to events unfolding across billions of kilometers and billions of years. ## Conclusion The Solar System is a magnificent celestial neighborhood shaped by gravity, motion, and time. Born from a cloud of gas and dust approximately 4.6 billion years ago, it grew into a complex system centered on the Sun and populated by planets, moons, asteroids, comets, and countless smaller objects. Its mechanics are governed by elegant physical laws that keep worlds in motion and maintain cosmic order. Yet within that order exists extraordinary diversity. From the blazing surface of Mercury to the icy depths beyond Neptune, every region of the Solar System tells a different chapter of an ancient story. The Solar System is not merely the backdrop of human existence. It is the environment that made our existence possible. It is the stage upon which Earth formed, life emerged, and intelligence evolved. Every exploration mission, every telescope observation, and every scientific discovery deepens our understanding of this remarkable cosmic home. When we look up at the night sky, we are not simply gazing into space. We are looking into our own neighborhood—a vast, beautiful, and ever-changing celestial community that continues to inspire wonder, curiosity, and the timeless human desire to explore.

Aim. We present and interpret the data of the nearby hydrogen-deficient but helium-rich superluminous supernova SN 2021bnw which reached a magnitude of -20.7 at maximum luminosity in g band. Methods. We discuss the light curves and spectra of SN 2021bnw based on its spectro-photometric follow up exploiting different observational facilities. We reproduce the NIR spectrum of SN 2021bnw with TARDIS to inspect the chemical composition at late photospheric phases and identify helium features. We also use a STELLA model coupling hydrodynamics and radiation transport to constrain the physical parameters of the explosion assmunig a 56Ni+CSM scenario. Results. We suggest that SN 2021bnw was mainly powered by the interaction of the ejecta with a previously lost He-rich circumstellar material, coupled with a central power source. Conclusions. This work expands the data sample of He-rich superluminous supernovae rich (SLSNe Ib) and, assuming a single progenitor scenario, can constrain the masses and the physics of their progenitors.

"These are our memories!" "We are going home..." Universal has debuted a fabulous second trailer for the movie Forgotten Island, an animated adventure about two best friends. Opening in theaters starting in September in just a few months. From DreamWorks Animation comes a vibrant, emotional story about two lifelong best friends who must come together

IGR J17480-2446 is a low-mass X-ray binary, harboring an exceptional accreting pulsar (a neutron star) with an unusual spin frequency of 11 Hz and a very slow post-outburst crust cooling. The former may imply that it is observed at an early stage of recycling, while the latter was shown to indicate the presence in the outer crust of a low thermal conductivity layer, possibly made of glass. Here we argue that the glass layer formation is a natural result of accretion induced failure of pristine cold crystal crust. This allows us to determine the mass of the accreted material as $ΔM \approx 2.4\times 10^{-6}~M_\odot$, confirming very early accretion stage for this neutron star. An analysis of spin and thermal state reveals a peculiar set of neutron star birth properties which is commonly associated with `recycled' neutron stars, i.e.\ those that have been experiencing prolonged periods of accretion from a companion. We speculate that such birth properties may represent the outcome of neutron star formation in an electron-capture supernova.

Using data from NASA’s Chandra X-ray Observatory, astronomers may have found a supernova remnant – seen in this June 11, 2026, image – in an intriguing neighborhood in the middle of the Milky Way galaxy. Supernova remnants are the expanding remains of exploded stars and provide elements like iron, oxygen, and silicon that are critical […] The post NASA’s Chandra Finds Possible Supernova Remnant appeared first on NASA Science.

Жизнь звезд тесно переплетена с их "родственными связями", а гамма-телескопы продолжают раскрывать перед нами сложную картину космической эволюции.

When astronomers first observed iPTF14hls in September 2014, they identified it as a supernova and expected it to dim within 100 days. Instead, it kept erupting. Over approximately 1,000 days, its brightness peaked at least five times, varying by as much as 50 percent. — Read the rest The post A star discovered in 2014 has exploded six times and none of the theories explain it appeared first on Boing Boing.

В железомарганцевой корке со дна Тихого океана обнаружены изотопы, указывающие на редкое слияние нейтронных звёзд в глубоком прошлом, продукты которого до сих пор фиксируются в земных слоях

Gamma-ray bursts (GRBs) are classified as long (LGRBs) and short (SGRBs), with collapsars and compact-object mergers (NS-NS or NS-Black Holes) as progenitors, respectively. LGRBs are expected to follow the cosmic star formation rate (SFR), while SGRBs follow a delayed version of the SFR. However, this division has come under question, most prominently by observational evidence of an excess of LGRBs at low redshifts by several investigations, summarized in \cite{Petrosian_2024}. Two recent observations of low-redshift LGRBs show associations with kilonovae. Both of these indicate compact mergers as a potential source of LGRBs as well. Most results showing this separation are based on analyses of small (less than 200) samples of LGRBs with measured redshifts. The aim of this paper is to use a larger sample of LGRBs. The number of LGRBs with measured redshifts has increased by more than a factor of 2 over the last decade. To this data set we add a sample of LGRBs whose redshifts are estimated using a machine learning (ML) method (\cite{Narendra_2025}). To account for the observational selection bias due to redshift measurements, we use the non-parametric, non-binning Efron-Petrosian method to establish the degree of correlation between luminosity and redshift, \textit{the luminosity evolution}, and then use the Lynden-Bell $C^-$ method to obtain the luminosity function. We find a low redshift excess for the larger sample with measured redshifts. Adding the sources with ML-estimated redshifts, which shows overabundance of the mid-range redshifts, the excess is reduced.

Star explosion millions of light-years away ejected life's building blocks like carbon, nitrogen, and oxygen. Elements up to iron produced in violent process. Core remains after explosion.