iiinova — where your digital self keeps evolving

Keaton Bell @astrokeat.bsky.social · 11/09/2026

New paper led by @thegraduatecenter.bsky.social Physics PhD student Andrew Dublin demonstrating five important strategies for characterizing results of fitting grids of asteroseismic models to measurements of white dwarf pulsation periods. ui.adsabs.harvard.edu/abs/2026arXi... #stellarastro

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Keaton Bell @astrokeat.bsky.social · 11/09/2026

We demonstrate the method for the helium-atmosphere pulsating white dwarf WD 0158-160 observed by NASA's TESS telescope. We obtain robust probability distributions for mass and effective temperature, where we have propagated uncertainty from the star's unknown chemical composition profile.

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Keaton Bell @astrokeat.bsky.social · 11/09/2026

Monotonic trends of mean period spacing and absolute magnitude cross the plane of mass and effective temperature in opposing directions, making these synergistic measurements for pinning down these fundamental global parameters of pulsating white dwarfs.

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Keaton Bell @astrokeat.bsky.social · 11/09/2026

New paper out from me an my colleague Agnes Bischoff-Kim "A Seismic Technique for Obtaining White Dwarf Fundamental Parameters from Mean Period Spacings and Astrometry"! ui.adsabs.harvard.edu/abs/2026arXi... #stellarastro

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Keaton Bell @astrokeat.bsky.social · 04/09/2026

Demonstration of beating with combs.

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Keaton Bell @astrokeat.bsky.social · 06/08/2026

Family photo of the scientific descendants of Don Winget (UT-Austin) at the European White Dwarf Workshop this week in Vienna.

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Keaton Bell @astrokeat.bsky.social · 04/08/2026

Andrew Dublin and me presenting our posters at EuroWD in Vienna this week.

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Keaton Bell @astrokeat.bsky.social · 07/07/2026

TESS data analysis led by CUNY @thegraduatecenter.bsky.social PhD student Nikoo Hosseininezhad. More to come in this series!

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Keaton Bell @astrokeat.bsky.social · 01/07/2026

The perfect birthday gift to me :)

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Keaton Bell @astrokeat.bsky.social · 26/06/2026

If you use Pyriod, try v0.4.1 that uses much less memory and can therefore handle larger data sets (like a whole year of TESS short cadence data). pypi.org/project/Pyri...

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Keaton Bell @astrokeat.bsky.social · 21/06/2026

Earl Bellinger and I vibecoded this "asteroseismology clock" as an art project/experiment with Codex. Clock hands trace ray paths of pulsations from a model of the Sun, with timescales changed to standard h:m:s clock times. #stellarastro earlbellinger.com/apps/sun-clo...

earlbellinger.com

Bellringer Sun Clock

A live asteroseismology clock where solar oscillation ray paths trace the hours, minutes, seconds, and year.

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Keaton Bell @astrokeat.bsky.social · 13/06/2026

Check out the #AAS248 @aas.org meeting iPoster "The Seismic Technique for Accurate White Dwarf Parameters" presented by Agnes Bischoff-Kim about our recently-submitted paper: aas248-aas.ipostersessions.com/Default.aspx... #stellarastro

aas248-aas.ipostersessions.com

aas (iPosterSessions - an aMuze! Interactive system)

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Keaton Bell @astrokeat.bsky.social · 13/06/2026

New #stellarastro paper with @jjhermes.bsky.social about a large outburst from the bright pulsating white dwarf star GD 1212. With fantastic data from NASA's Kepler/K2! The modeling effort was led by CUNY @thegraduatecenter.bsky.social PhD student Andrew Dublin. Read here: arxiv.org/abs/2606.09987

Mode Instability and a Massive, Isolated Outburst in the Pulsating White Dwarf GD 1212
Hermes, J. J. ; Bell, Keaton J. ; Dublin, Andrew H. ; Montgomery, M. H. ; Kawaler, Steven D. ; Clark, Ian ; Vanderbosch, Zachary P. ; Dunlap, Bart H. ; Tremblay, P.-E. ; Chote, Paul ; Gaensicke, Boris T.

The top panel shows the full 76.1-day K2 Campaign 12 light curve of GD 1212, with observations roughly every 60 s.
A large flux outburst is observed on Day 61; a zoom-in on the event is shown in the bottom panel. A sinusoidal model of the
dominant pulsation periods in roughly 4-hr windows before, during, and after the outburst are labeled on the plot in red, green,
and blue, respectively. The dominant pulsation signals in outburst have generally shorter periods and larger amplitudes, but
return roughly to quiescent behavior in less than 1 day.

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Keaton Bell @astrokeat.bsky.social · 05/06/2026

Congratulations to our graduating astrophysics Masters students!!

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Keaton Bell @astrokeat.bsky.social · 15/05/2026

27 institutions represented at the New York Area Exoplanet Meeting at AMNH today :)

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Keaton Bell @astrokeat.bsky.social · 15/03/2026

Pyriod v0.3.4 fixes a bug that made some estimates of amplitude uncertainties numerically unstable. pypi.org/project/Pyri...

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Keaton Bell @astrokeat.bsky.social · 28/02/2026

New blog post with animations demonstrating key considerations for periodogram analysis: signal-to-noise, resolution, Nyquist aliasing, and aliasing due to gaps in the data. #astromethods Read here: keatonb.github.io/archivers/ft

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Keaton Bell @astrokeat.bsky.social · 30/07/2025

Great to revisit this photo! Many people I now know in the field whom I don't recall meeting at this, one of my first real science meetings.

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Keaton Bell @astrokeat.bsky.social · 30/07/2025

RIP to Bill Paxton, lead developer of MESA. I feel privileged to have learned from the man himself at the 2012 MESA Summer School. #stellarastro #astrocode

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Keaton Bell @astrokeat.bsky.social · 09/07/2025

A minor update to Pyriod is now available (v0.3.3), addressing some pesky depreciation warnings that would crop up. pypi.org/project/Pyri...

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Keaton Bell @astrokeat.bsky.social · 09/07/2025

Also another notebook showing how to automate prewhitening analysis (I will try to build more convenience functions into Pyriod for this soon). github.com/keatonb/Pyri...

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Keaton Bell @astrokeat.bsky.social · 09/07/2025

For this presentation, I have also uploaded a demonstration of how to use Pyriod to measure O-C diagrams to track timing variations of a signal. github.com/keatonb/Pyri...

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Keaton Bell @astrokeat.bsky.social · 09/07/2025

At the 9th TESS/16th Kepler Asteroseismic Science Consortium Workshop this week in Vienna. I'm presenting this poster on my code Pyriod for pre-whitening frequency analysis of astronomical time series data. #astromethods

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Reposted by Keaton Bell

NSF–DOE Rubin Observatory @rubinobservatory.org · 23/06/2025

Here it is: the first set of riches from Rubin's Cosmic Treasure Chest! Introducing NSF–DOE Rubin Observatory's first wide and deep view of the cosmos, the southern region of the Virgo Cluster. Rubin produced this image in just 10.5 hours over parts of 7 nights! 🔭🧪 youtu.be/Gitit3LwQ20

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Keaton Bell @astrokeat.bsky.social · 09/06/2025

I present the #astrocode Pyriod for interactive or scripted pre-whitening frequency analysis of astronomical time series data. See the demo of #stellarastro #TESS data analysis of a pulsating white dwarf star. Check it out at github.com/keatonb/Pyriod/.

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Keaton Bell @astrokeat.bsky.social · 09/06/2025

Check out the #AAS246 iPoster "White Dwarf Asteroseismology in the Age of Gaia Astrometry" from Andrew Dublin, Agnes Bischoff-Kim and myself: aas246-aas.ipostersessions.com/Default.aspx... #stellarastro

aas246-aas.ipostersessions.com

aas (iPosterSessions - an aMuze! Interactive system)

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Keaton Bell @astrokeat.bsky.social · 09/06/2025

Check out the #AAS246 iPoster "TESS CROWDSAP Errors from White Dwarf Observations" from Nikoo Hosseininezhad and myself: aas246-aas.ipostersessions.com/default.aspx... #stellarastro

aas246-aas.ipostersessions.com

aas (iPosterSessions - an aMuze! Interactive system)

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Keaton Bell @astrokeat.bsky.social · 09/06/2025

The development of Pyriod is supported by the National Science Foundation under Grant No. AST-2406917.

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Keaton Bell @astrokeat.bsky.social · 09/06/2025

The interface works in Jupyter, and it can also be scripted for automated analysis. We are grateful to lightkurve, astropy, lmfit, qgrid, and qgridnext, which make Pyriod work. I am working to improve tutorials and documentation. Submit issues/feature requests at github.com/keatonb/Pyriod

github.com

GitHub - keatonb/Pyriod: Python implementation of basic period detection and fitting routines for astronomical time series.

Python implementation of basic period detection and fitting routines for astronomical time series. - keatonb/Pyriod

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Keaton Bell @astrokeat.bsky.social · 09/06/2025

Pyriod is inspired by Period04 (www.period04.net), aiming to provide a similar interactive data analysis experience for the modern Python workflow, with open-source code, and with a faster periodogram better-suited for the big data era.

period04.net

Period04 - Homepage

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Keaton Bell @astrokeat.bsky.social · 09/06/2025

Our reward for completing this process is a table of signal frequencies, amplitudes, and phases, with estimated uncertainties. These measurements of resonant frequencies of a white dwarf star are published and interpreted in Bell et al. (2019, ui.adsabs.harvard.edu/abs/2019A%26A...632A..42B).

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Keaton Bell @astrokeat.bsky.social · 09/06/2025

The fit to the light curve reveals the complex variability that we otherwise couldn't visibly see for all the measurement noise, shown here for one day of the TESS light curve.

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Keaton Bell @astrokeat.bsky.social · 09/06/2025

Pyriod can enforce strict relationships between combination frequencies and independent frequencies when they are identified by their arithmetic relations. We proceed to pre-whiten all significant signals, with combinations marked with gold diamonds.

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Keaton Bell @astrokeat.bsky.social · 09/06/2025

Three signals down, but the next three are "combination frequencies" that appear at precise sums, multiples, and differences of frequencies. If the first three signals are f0, f1, and f2, this next cluster of peaks are f0+f1, 2*f0, and f0+f2.

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Keaton Bell @astrokeat.bsky.social · 09/06/2025

We then identify additional signals from the periodogram of fit residuals (the "pre-whitened" data). Pyriod displays the periodogram of the residuals in blue (highest peak marked). The model is displayed in green. In practice, we move significant peaks from blue to green.

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Keaton Bell @astrokeat.bsky.social · 09/06/2025

We "pre-whiten" signals by fitting and subtracting sinusoids from the light curve. We currently fit the frequency, amplitude, and phase of one sinusoidal signal. The data may be noisy, but TESS collected enough that we detect this signal to high significance.

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Keaton Bell @astrokeat.bsky.social · 09/06/2025

The periodogram displays the frequency content of the light curve, and we identify significant signals as having amplitudes well above the noise floor. The red curve gives an approximate significance threshold, and Pyriod marks the highest peak for inclusion in the model. Let's add it.

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Keaton Bell @astrokeat.bsky.social · 09/06/2025

The pre-whitening algorithm is a method for measuring sinusoidal signals in time series data. It is best suited for signals that are coherent for the duration of the observations. We start with the periodogram of the TESS Sector 3 light curve of the pulsating white dwarf WD 0158-160.

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Keaton Bell @astrokeat.bsky.social · 09/06/2025

Had to withdraw my #AAS246 poster due to COVID, but let me demo "Pyriod: Interactive Pre-Whitening Frequency Analysis in Python." Here is a quick guide to reproducing the analysis of TESS data on a pulsating white dwarf from Bell et al. (2019, ui.adsabs.harvard.edu/abs/2019A%26A...632A..42B).

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Keaton Bell @astrokeat.bsky.social · 08/06/2025

Disappointed to be missing #AAS246 this week, but I gotta keep y'all safe.

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Reposted by Keaton Bell

Dr. Skylar Grayson @skylargrayson.bsky.social · 01/06/2025

Following the inspiration of @ohdearz.bsky.social @theplanetaryguy.bsky.social @jtuttlekeane.bsky.social here’s the NASA fleet with the proposed budget cuts. Red X’s will be fully defunded, green X’s will lose all NASA funding but have other funding sources, and exclamation point means >50% cuts

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Reposted by Keaton Bell

Emily McPike @astrowithemily.bsky.social · 29/05/2025

I'm coordinating a How to Read a Paper workshop for undergrads i and was wondering if people have any resources they have found helpful for outlining readings/building that skill? Any resources or advice help!

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Reposted by Keaton Bell

Mark Popinchalk @markpopinchalk.bsky.social · 08/05/2025

Astronomy is in trouble, but you can help! 🔭🧪 I made this video as part of the @aas.org #savescience week of action. Check out their resources on how you can help here aas.org/advocacy/get...

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Reposted by Keaton Bell

CUNY Graduate Center @thegraduatecenter.bsky.social · 19/09/2024

Congratulations to Andrew Ayala, who finished his master’s degree in Astrophysics and has started the Ph.D. Program in Physics at the Graduate Center! He shares advice for new students entering the world of astrophysics www.gc.cuny.edu/news/phd-nex...

gc.cuny.edu

Ph.D. Is Next Stop for an Aspiring Astrophysicist

Astrophysics graduate Andrew Ayala prepares to pursue a Ph.D. and inspire the next generation of scientists.

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Keaton Bell @astrokeat.bsky.social · 25/04/2025

Looks like this is the real deal, folks. Very exciting! First confirmed intact planet transiting a white dwarf star!

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Keaton Bell @astrokeat.bsky.social · 01/04/2025

This was a transformative meeting for me as a senior graduate student. I met many wonderful collaborators and mentors here.

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Reposted by Keaton Bell

M.S. Astrophysics CUNY @cunygc-astro.bsky.social · 01/04/2025

M.S. in Astrophysics at the CUNY Graduate Center is accepting applications for the 2025 Fall semester! Apply at www.gc.cuny.edu/astrophysics... Application deadline is April 15, 2025. 💫 #CUNY #cuny #cunygc #amnh #astrophysics #astro @thegraduatecenter.bsky.social @natural-history.bsky.social

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