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Accurate red giant distances and radii with asteroseismology

Zinn, Joel Coyle
http://orcid.org/0000-0002-7550-7151
http://rave.ohiolink.edu/etdc/view?acc_num=osu1555582282659221

Abstract Details

2019, Doctor of Philosophy, Ohio State University, Astronomy.
Four billion years from now, the Sun will evolve into a red giant: its surface will become a thousand degrees cooler, and it will grow to be tens of times larger. Because of their size, red giants like the future Sun can shine hundreds of times brighter than the Sun, and can be seen from the farthest reaches of our Galaxy. As such, they are important tracers for studies of the evolution of the dynamics and structure of the Galaxy. Knowing the distances to these stars is essential for such work, as is knowing their intrinsic stellar properties like mass and radius, which in combination with stellar models yield ages. In this dissertation, I use data from space-based missions Kepler, K2, and Gaia to test the accuracy of red giant distances and radii that can be derived from theoretical relations between the stellar radius and photometric variability induced by sound waves on the stellar surface---a technique within the scope of what is known as asteroseismology. I begin by presenting the Bayesian Asteroseismology data Modeling (BAM) pipeline, an automated asteroseismology pipeline that returns oscillation parameters that describe the essential characteristics of the sound waves supported in the stellar interior and that are seen on the surface as photometric variability ("solar-like" oscillations). The parameters BAM estimates can be used to yield asteroseismic masses and radii. I have designed BAM to specially process K2 light curves, which suffer from unique noise signatures that can confuse asteroseismic analysis, though it may be used on any photometric time series---including those from Kepler and its successor, TESS. I then turn to testing the asteroseismic red giant distance and radius scale with Gaia parallaxes and Kepler asteroseismology. I am able to simultaneously test both the asteroseismic and Gaia systematics in distances and radii, self-consistently calibrating them. Using the first data release of Gaia parallaxes, I present evidence for a spatially-dependent systematic error based on comparisons to asteroseismic parallaxes in the Kepler field, and present a parametrized model of the angular dependence of these systematics. I build on this methodology to present an independent confirmation of the zero-point offset noted by the Gaia team present in Gaia Data Release 2 (DR2) parallaxes. I also quantify the spatially-correlated DR2 parallax errors in the Kepler field, and find that the amplitude of these correlations are in global agreement with the covariances published by the Gaia team. I use this corrected Gaia distance scale to compare asteroseismic radii of 500 dwarfs and 3,600 red giants from the Kepler mission to radii based on Gaia parallaxes. The agreement, when accounting for corrections to the Gaia parallaxes, is within 2% ± 2% (syst.) for stars with radii between 0.8R☉ and 30R☉. I identify differential trends as a function of radius in the radius agreement at the 2% ± 2% (syst.) level. I find that asteroseismic dwarf radii are on a parallactic scale at the 2% ± 2% (syst.) level, which supports recent comparisons between asteroseismic radii and Gaia radii for dwarfs. For giants, I conclude asteroseismic radii are on the parallactic scale to within 1% ± 2% (syst.).
Marc Pinsonneault (Advisor)
Jennifer Johnson (Committee Member)
Krzysztof Stanek (Committee Member)
284 p.
Astronomy; Astrophysics
red giants; asteroseismology; stars; parallaxes

Recommended Citations

Citations

  • Zinn, J. C. (2019). Accurate red giant distances and radii with asteroseismology [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1555582282659221

    APA Style (7th edition)

  • Zinn, Joel. Accurate red giant distances and radii with asteroseismology. 2019. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1555582282659221.

    MLA Style (8th edition)

  • Zinn, Joel. "Accurate red giant distances and radii with asteroseismology." Doctoral dissertation, Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1555582282659221

    Chicago Manual of Style (17th edition)

osu1555582282659221
545
© 2019, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.