iiinova — where your digital self keeps evolving

Travis Metcalfe @travis-metcalfe.bsky.social · 20/08/2026

This summer I spoke with science journalist Zack Savitsky, who wrote this in-depth article for NatGeo about our updated picture of magnetic stellar evolution, and what it means for understanding our own Sun and the chances of life in other solar systems. www.nationalgeographic.com/science/arti...

nationalgeographic.com

The Sun’s Magnetic Field is Behaving Oddly. Astronomers Still Don’t Know Why.

Scientists say our star might be in a midlife crisis of sorts. What does that mean for life?

030

Travis Metcalfe @travis-metcalfe.bsky.social · 29/07/2026

Can someone explain to me how this pink data point validates gyrochronology for old solar twins? The age is 6-sigma above, and the Prot is 3-sigma below, the prediction! And the isochrone age is precise to 4%? 😂 ui.adsabs.harvard.edu/abs/2025ApJ....

Age-Rotation plot (Fig.4 from Carvalho-Silva+2025) with error bars duplicated to show how inconsistent the pink point is with the prediction.

000

Travis Metcalfe @travis-metcalfe.bsky.social · 08/07/2026

Why are there so few points on this plot? Because we need: 👉 Stokes V snapshot with S/N~2000 (dipole field) 👉 existing measurement of Lx (mass-loss rate) 👉 existing measurement of rotation period All of this for stars near and below the solar activity level where WMB occurs. Help us add more points!

Observed torque relative to Skumanich-like model predictions versus Rossby number relative to the solar value. The functional form of the fit dotted line (90% confidence interval in gray) is predicted by the idea that the efficiency of the solar dynamo is currently collapsing (Hopf bifurcation; Cameron & Schussler 2017).

021

Travis Metcalfe @travis-metcalfe.bsky.social · 23/06/2026

During a splinter session at #CoolStars23 last week, Jennifer van Saders presented our latest results to constrain the onset of antisolar DR in subgiants. youtu.be/fiq02okcFfM

youtu.be

Anti-Solar Differential Rotation May Have Revived Magnetic Braking in the Subgiant 31 Aquilae

YouTube video by Travis Metcalfe

011

Travis Metcalfe @travis-metcalfe.bsky.social · 11/05/2026

I've been showing this plot in seminars for the past six months, and I finally decided to publish a research note about it (not yet on @arxiv.bsky.social, still stuck in moderation). Take a look: iopscience.iop.org/article/10.3...

Activity cycle period as a function of chromospheric activity level (a proxy for stellar age) for stars in the California Legacy Survey.

140

Travis Metcalfe @travis-metcalfe.bsky.social · 05/05/2026

👉 Tomorrow (May 6 at 2:00pm MDT) I'll give HAO a sneak preview of a talk that I'm presenting next week at Stanford "Stellar Evidence of a Collapsing Solar Dynamo" www2.hao.ucar.edu/stellar-evid...

Title slide: "Stellar Evidence of a Collapsing Solar Dynamo"

111

Travis Metcalfe @travis-metcalfe.bsky.social · 20/02/2026

SNEAK PREVIEW: after the collapse of the global dynamo stalls main-sequence spin-down for billions of years, physical expansion on the subgiant branch finally allows stars to reach the transition to anti-solar DR (~1.1 Ro_crit), restoring the large-scale field and reviving magnetic braking!

Ratio of the observationally estimated and model wind braking torque as a function of Rossby number normalized to the solar value. The dotted line and gray shaded region illustrates the fit and 95% confidence interval described by Metcalfe+2025b. The revived magnetic braking in 31 Aql at higher Ro is evident, and quadratic growth is illustrated schematically with a dashed line.

051

Travis Metcalfe @travis-metcalfe.bsky.social · 02/01/2026

It took 10 years to trace Weakened Magnetic Braking back to it's root cause (the collapse of the global stellar dynamo), but next week at #AAS247 you can hear me explain how we did it in less than 10 minutes! Thursday, January 8th at 10:10am in room 222C. submissions.mirasmart.com/AAS247/Itine...

Title slide for a presentation at #AAS247

041

Travis Metcalfe @travis-metcalfe.bsky.social · 04/12/2025

"Nature is so rich you are unlikely to look carefully at anything without learning something new, particularly in unexplored territory... do something nobody thinks is interesting. Trust me: it will be." ~Ed Nather whitedwarf.org/education/ad...

000

Travis Metcalfe @travis-metcalfe.bsky.social · 20/10/2025

When I wrote this "Quick Study" on Weakened Magnetic Braking for @physicstoday.bsky.social in 2018, we already had the physical picture largely correct – we just didn't have all of the evidence in hand to support it. Now we do. physicstoday.aip.org/quick-study/...

physicstoday.aip.org

The Sun’s magnetic midlife crisis

Old Sun-like stars observed by the Kepler Space Telescope spin faster than astronomers expected. Apparently, they experience a dramatic shift in their rotation and magnetism at about middle age.

031

Travis Metcalfe @travis-metcalfe.bsky.social · 25/09/2025

Looking forward to giving the LASP seminar this afternoon, 1:00pm in SPSC-N100 and on zoom (preview of an astronomy colloquium next week at NMSU). lasp.colorado.edu?science-semi...

110