Jennifer Van Saders
University of Hawaii at Manoa, HI·Astronomy & Astrophysics
Stars like the Sun spin more slowly as they age. Their winds, guided by magnetic fields, carry away spin over billions of years, a process called magnetic braking.
- Fields
Astronomy & Astrophysics
Physics
- Topics
stellar rotation
magnetic braking
gyrochronology
- Grants
- 2 known grants, through Aug 2028
What they work on
- Model how spin is transported inside K dwarfs by fluid motions, gravity waves and magnetism, using new magnetic braking laws in the Yale Rotating Stellar Evolution Code (YREC) to explain their unexpectedly fast spin and lasting activity.
- Test the K dwarf spin models against cluster and field star spin periods, magnetic activity signs, light-element depletion trends and new spectropolarimetric measurements of magnetic fields.
- Measure magnetic field strength and geometry in unusual Hyades K dwarfs using spectropolarimeters, which detect magnetic fields from polarized light: PEPSI on the Large Binocular Telescope and ESPaDOnS and SPIRou on the Canada-France-Hawaii Telescope.
- Determine how magnetic strength and complexity change with rotation and mass in 12 older Sun-like stars, using PEPSI polarized spectra, simultaneous activity measurements from the NRES spectrographs and follow-up ESPaDOnS magnetic maps.
More about the research
Because of this, a star's spin rate can serve as a clock. This method of dating stars, called gyrochronology, also helps estimate the ages of the planets that orbit them. But some stars do not follow the rule. Older Sun-like stars appear to stop slowing down as their magnetic fields weaken and become more complex. Cooler K dwarfs stay active and spin faster than expected. This research combines stellar models with telescope observations of magnetic fields to explain these exceptions. The aim is to make star ages more reliable.
Why it matters
Knowing the ages of stars matters for understanding the planets that orbit them. Many star ages come from spin rates, so the results could correct gyrochronology for older Sun-like stars and K dwarfs. That would give more accurate ages for stars that host planets. The magnetic measurements could also inform long-term predictions of space weather for the Sun and other planetary systems.
Known grants
From NIH and NSF research grants. Labs often have other funding we can't see.
Closest labs
Andrew Mann
University of North Carolina at Chapel Hill, NC·Astronomy & Astrophysics·Early-career
Measure luminosity, radius, mass and age to better than 5% accuracy for 5–500 million-year-old K and M stars by analyzing light curves of eclipsing and astrometric binaries found by Gaia, K2 and TESS.
Christopher Kochanek
Ohio State University, OH·Astronomy & Astrophysics
Measure what fraction of massive-star core collapses fail and form a black hole without a supernova, by monitoring evolved stars in 27 nearby galaxies with the Large Binocular Telescope.
Douglas Gies
Georgia State University, GA·Astronomy & Astrophysics
Measure mass-loss rates of massive stars by comparing CHARA Array interferometric observations, which combine several telescopes for fine detail, at different wavelengths using the new SPICA visible-light instrument.
The school
University of Hawaii at Manoa: 23 labs on PI Pages, $376M a year on research, 182 research doctorates a year.
Reach out
A start for your email. Fill in the brackets.