Calibrating Stellar Models in the TESS Era

Jamie TayarWith Zach Claytor and the

APOGEE-Kepler, APOGEE-TESS, & TESS Subgiant Collaborations

TESS Science ConferenceJuly 30, 2019

Hubble Fellow@StellarTayar

Stellar Model

Model Physics Uncertain● Convection● Rotation● Mixing● Diffusion● Atmosphere Boundary Condition● Helium● Solar composition● ...

Stellar Model Grid

Stellar Model Grid

Estimate Stellar Properties

TOI-1411.04 ± 0.03 Mo

TOI-1971.30 ± 0.09 Mo

TOI-141Espinoza+(2019)

TOI-197Huber+ (2019)

Impact of Model Choice: YREC

TOI-1411.04 ± 0.03 Mo

TOI-1971.30 ± 0.09 Mo

Grid:YREC

Impact of Model Choice: MIST

TOI-1411.05 ± 0.03 Mo1.04 ± 0.03 Mo

TOI-1971.31 ± 0.06 Mo1.30 ± 0.09 MoGrid:

YRECMIST

MIST: Choi+(2016)

Impact of Model Choice: Dartmouth

TOI-1411.07 ± 0.02 Mo1.05 ± 0.03 Mo1.04 ± 0.03 Mo

TOI-1971.33 ± 0.07 Mo1.31 ± 0.06 Mo1.30 ± 0.09 Mo

Grid:YRECMISTDartmouth

Dartmouth: Dotter+(2008)

Model Choice Matters

TOI-1411.07 ± 0.02 Mo1.05 ± 0.03 Mo1.04 ± 0.03 Mo

TOI-1971.33 ± 0.07 Mo1.31 ± 0.06 Mo1.30 ± 0.09 Mo

Grid:YRECMISTDartmouth

Offsets of ~4% in inferred mass depending on model grid used

Model Choice Matters

TOI-1411.07 ± 0.02 Mo1.05 ± 0.03 Mo1.04 ± 0.03 Mo

TOI-1971.33 ± 0.07 Mo1.31 ± 0.06 Mo1.30 ± 0.09 Mo

Grid:YRECMISTDartmouth

Offsets of ~4% in inferred mass depending on model grid used No strong metallicity

dependence

Take Away

When estimating stellar properties from models,

either inflate the error bars to account for model

systematics or compare to multiple models.

Stellar Model Grid

Sample light curve from Huber+ (2019)

Di Mauro+ (2011)

Asteroseismic Masses

Stellar Models

APOGEE-Kepler Subgiants

Serenelli+(2017) (inc Tayar)

APOGEE-Kepler Subgiants

Serenelli+(2017) (inc Tayar)

APOGEE-Kepler Subgiants

Models from Claytor+(2019)

APOGEE-Kepler Subgiants

Giants

APOGEE-Kepler Subgiants

GiantsGiantsOffset- Tayar+ 2017

APOGEE-Kepler Subgiants

Models do well for subgiants

APOGEE-Kepler Subgiants

Transition Unclear- Need More data

TESS

APOGEE-Kepler Subgiants

Transition Unclear- Need More data

TESS Subgiants

Summary

● Stellar models need calibration● Model choice impacts inferred mass by ~4%● Predicted HR diagram position ~ correct● Kepler stars are a good but insufficient sample

for testing models of subgiants● TESS will allow us to add up to 300 more

similarly well characterized subgiants

Expected Rotation

Expected Rotation

Rotation Difference

Rotation Difference

Giants too slow to measure

Rotation Difference

Scatter for hot stars

Rotation Difference

Subgiants spin faster than expected ?

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