Jennifer van Saders

About

I am an Assistant Astronomer at the Institute for Astronomy at the University of Hawaii. My primary research area is the study of stellar structure and evolution, where I work at the intersection of theory and observation, building stellar models that reproduce our increasingly precise observations of stars. I am particularly interested in inferring precise stellar ages, which can provide a chronology to exoplanetary, galactic, and extragalactic astrophysical systems alike.

I obtained my Bachelor's degree from Rutgers, The State University of New Jersey, and my Ph.D. from the The Ohio State University. I was a Carnegie-Princeton Fellow at Carnegie Observatories before beginning at the IfA in 2017.

CV

Research

Rather than reading, you can listen.

Gyrochronology

Perhaps the most challenging fundamental stellar property to measure is age, and yet ages are critical to our understanding of the chronology and evolution of nearly all astrophysical systems. As such, we actively seek to find ways to infer more precise stellar ages. Gyrochronology is one such method, and it relies on the fact that the rotation rates of stars change over their lifetimes. Stars like the Sun are born rotating relatively rapidly rotating and spin down with time by losing angular momentum to magentized stellar winds. Gyrochronology is particularly promising in stars less massive than the Sun, where all other age-dating techniques are imprecise or fail entirely. However, the rate of stellar spin-down hard to predict; our existing period-age relations rely heavily on calibrators (of known age and rotation period) and relatively simple models of angular momentum loss. My group's efforts focus on 1) improving models of angular momentum loss, transport, and evolution, and 2) expanding the set of calibrating stars to a wider range of masses, ages, and compositions to expand the utility of gyrochronology. We use systems such as open clusters, wide binaries, and asteroseismology to expand the calibrator set.
Papers of interest: Claytor et al. (2021), Claytor et al. (2020), van Saders et al. 2019, van Saders et al. (Nature, 2016)

The Evolution of Stellar Magnetism

Stars like the Sun drive magentic dynamos through the combination of convection and rotation. These dynamos build the large scale magnetic features in stars, produce space weather events (flares, coronal mass ejections), and may impact the habitability of our planet and others. Despite the fact that stellar magnetism is ubiquitous, we have only a basic understanding of how it depends on stellar type and age. In our present day Sun, sunspots appear and disappear over timescales of weeks to months, and the overall activity level varies over decade timescales. Using old, sun-like stars with properties measured from asteroseismology, we found that the Sun may be in the midst of a mid-life crisis and transition in its magnetic behavior. My group is involved in ongoing efforts to understand the magentic behavior of stars on all scales for stars very similar and very different from the Sun. For more reading: Metcalfe, van Saders et al. (2021), Metcalfe, van Saders et al. (2020), Metcalfe & van Saders (2017)

Precision Stellar Properties

Precision stellar properties are useful for a broad range of science questions, ranging from the formation and evolution of our galaxy ("galactic archaeology") to an accurate census of exoplanet properties. Recent efforts to collect time-domain observations of stars from Kepler, K2 and TESS have opened up entirely new observables that we might exploit to constrain fundamental stellar properties. Coupled with precise distances and space motions from Gaia, a decade of photometric coverage from ground-based surveys (e.g. ASAS-SN, ATLAS), and large-scale spectroscopic surveys (APOGEE, LAMOST), we have access to a unprecedented volume of data at unprecendented precisions. UH grad Travis Berger recently released a catalog of precise stellar properties of stars in the Kepler field of view, as well as updated exoplanet properties.

Current Research Group

Zach Claytor (PhD)
Ryan Dungee (PhD, co-advised with Mark Chun)
Ellis Avallone (699-2, co-advised with Jamie Tayar)
Nick Saunders (699-2)

Past Students

Travis Berger (PhD, NASA FINESST Investigator, co-advised with Dan Huber, now a NASA NPP Fellow at NASA Goddard.)
Alison Dugas (699-1)
Erica Sawczynec (Undergraduate Honors Thesis, co-advised with Dan Huber, now a graduate student at UT Austin)
Jessica Schonhut-Stasik (699-2, now a graduate student at Vanderbilt)

Teaching

Astronomy 623: Stellar Interiors and Evolution (Fall 2018, Fall 2020)
Astronomy 790: Astro-ph Seminar (Fall 2017-present)
Astronomy 110: Survey of Astronomy (Fall 2019)

Talks

AAS 235 Plenary talk (click on talk 363 to listen)
KITP conference, "Planet-Star Connections in the Era of TESS and Gaia," invited talk
Huntington Library, "First Light, The Astronomy Century in California 1917-2017," invited talk (Track 7)
Asteroseismology for the Uninitiated at Carnegie Observatories, 2016

Contact

Address: 2680 Woodlawn Drive, Honolulu, HI, 96822, USA
Phone: (808)-956-6157
Email: jlvs@hawaii.edu

Elements

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    print 'Iteration ' + i;
    deck.shuffle();
    i++;
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