Sabina Sagynbayeva

i’m excited to announce that i am hiring (again)!

i am looking for a postdoc in computational astrophysics that’s excited about models of stellar transients and multi-messenger astronomy to join my group (star stuff @ steward) at @uarizona.bsky.social!

apply here ✨💥: aas.org/jobregister/...

Ah I just read the thread. It’s also not cool to do after the deadline passed. 🥲

Wait what happened? I just applied there last week….

Textbook cover for The Search for Extraterrestrial Intelligence: Theory and Practice by Jason T. Wright published by an American Astronomical Society and IOP Publishing Partnership (ebooks)

I wrote a textbook!

I hope you like it.

store.ioppublishing.org/page/detail/...

How we sharpened the James Webb telescope’s vision from a million kilometres away The only Australian hardware on board the legendary telescope is starting to fulfil its duties.

Thrilled to have two years' of work out, in a pair of papers led by @gradientrider.bsky.social and @maxecharles.bsky.social.

We've built a data-driven calibration of the James Webb Interferometer to near its fundamental limits for high-res imaging - explainer at @aunz.theconversation.com!

AMIGO: a Data-Driven Calibration of the JWST Interferometer The James Webb Space Telescope (JWST) hosts a non-redundant Aperture Masking Interferometer (AMI) in its Near Infrared Imager and Slitless Spectrograph (NIRISS) instrument, providing the only dedicate...

Amazing work solving a tricky calibration problem with JWST aperture masking data! Any hope to improve ground-based systematics with this general approach?
@benjaminpope.bsky.social

arxiv.org/abs/2510.09806

So excited that our paper is finally out! We analyzed archival TESS observations of RZ Psc and detected 24 transiting exocomets. And, Adalyn is an amazing undergrad applying for grad school this year!

Honestly this sounds fun even to me at my age too

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Polka-dotted Stars II: Starspots and obliquities of Kepler-17 and Kepler-63. Sabina Sagynbayeva et. al. https://arxiv.org/abs/2510.07130

Polka-dotted Stars II: Starspots and obliquities of Kepler-17 and Kepler-63 Starspots trace stellar magnetic activity and influence both stellar evolution and exoplanet characterization. While occultation-based spot analyses have been applied to individual systems, comparativ...

FYI:

arxiv.org/abs/2510.07130

This breakfast looks so goodddd🤤

I love this little support group that we virtually created with @astroshashank.bsky.social and @benjaminpope.bsky.social 🫶🏻 haha

Omg that was my attempt 8 months ago 🤣 the actual model code is in Zenodo: doi.org/10.5281/zeno...
But I do need to update my github repo! And I mostly used celerite but I do want to clean up and create a notebook with notes on sampling and stuff. :)

a plot of equipotentials in a binary star system, showing the Roche lobes and Lagrange points. The green color scheme makes it look like a teenage mutant ninja turtle...

I like my plot of equipotentials a lot, but I can never shake the fact that @sabinastro.bsky.social calls it the Teenage Mutant Ninja Turtle plot...

zingale.github.io/stars/notebo...

Will never unsee it

Anyways, like, comment, and hire me PLEASE!!!

In the end, we have a beautiful gyrochrone that you should take with a grain of salt just like any other gyrochronal sequence! Also my sample is the largest sample of rotation periods in an open cluster to date! Yay!

So if you assume that the uncertainties in period in period and temperature are gaussian, you can imagine that the point is sliding in those error bars until it decided whether to fall on our 5th order Legendre polynomial or not.

So the mixture model took the probability weights, and assigned some stars to the background based on their location in the period-temperature space. But we accounted for uncertainties in period and temperature too!

Instead, I wrote a Bayesian mixture model. The premise of the model is that some of the stars lie on the gyrochrone, but some of the are what we called “background stars”.

For gyrochrone, I wanted to just fit a quick polynomial but Will said he’d remove his name from the paper if I did that. 😂

We had to make some quality cuts, remove giants, and we were left with 271 reliable rotations.

So to account for that, my GP kernel was a sum of the Rotation term (i.e. the period) and the term that you can think of as a RealTerm in celerite so that it models the red noise.

I used gaussian processes to create a Bayesian model to extract periods from pretty low-amplitude light curves. We looked at PSDs and they still had this exponential decline that was the “red noise” in the data.

Getting periods from the crowded fields is HARD! So Isabel had to do her own photometry with superstamps, Will came up with a new-ish de-trending method, and I was left with maximizing likelihoods! 😄

Wuick thread while I am on the train!

Rotation Periods for Stars in Open Cluster NGC 6819 From Kepler IRIS Light Curves We present an updated catalog of stellar rotation periods for the 2.5 Gyr open cluster NGC 6819 using the Kepler IRIS light curves from superstamp data. Our analysis uses Gaussian Process modeling to ...

Okay people, welcome my new paper into the world!!! With Isabel Colman and @farrwill.bsky.social

arxiv.org/abs/2510.02255

Rotation Periods for Stars in Open Cluster NGC 6819 From Kepler IRIS Light Curves
https://arxiv.org/pdf/2510.02255
Sabina Sagynbayeva, Isabel L. Colman, Will M. Farr.

Some proposals are so short, and my only hope is that all the exoplaneteers in Physics departments have emailed their colleagues a schematic of transits so now everyone is on the same page lmao

I’m addicted to plasma I fear