Weakened magnetic braking supported by asteroseismic rotation rates of Kepler dwarfs

This talk was given as a Nordic Dynamo seminar (https://indico.fysik.su.se/category/369/) over Zoom for Stockholm University. The topic is the paper we published last year (Hall et al. 2021, https://ui.adsabs.harvard.edu/abs/2021NatAs...5..707H/abstract).

A recording of this talk can be found here: https://indico.fysik.su.se/event/7450/?print=1

This talk represents the "best" version of my seminars on this topic, which started off fairly statistics-heavy and was streamlined over time. If you're interested in hearing me give this talk as part of your institution's seminar series, (now with some excited new results from Kento, Petigura & Hall 2022), send me an email!

Transcript

1. Weakened magnetic braking supported by asteroseismic rotation rates of Kepler dwarfs Oliver J. Hall Nordic Dynamo seminar 8 June 2021 ojhall94 @asteronomer
2. 08 Jun 2021 O. J. Hall Nordic Dynamo seminar Who am I? Birmingham 2012-2020 ESA ESTEC 2020-2023
3. 08 Jun 2021 O. J. Hall Nordic Dynamo seminar Who am I? Asteroseismology of MS and RGB stars Bayesian Statistics (hierarchical models, GPs, etc.) Finding new ways for seismology to be useful
4. 07 Jun 2021 O. J. Hall Nordic Dynamo seminar Rotation & Hierarchical Models What is asteroseismology? How is it useful? Stellar rotation and gyrochronology Measuring asteroseismic rotation 1. 2. 3.
5. 07 Jun 2021 O. J. Hall Nordic Dynamo seminar Asteroseismology is the study of oscillations inside stars Credit: asterostep.eu
6. 07 Jun 2021 O. J. Hall Nordic Dynamo seminar CoRoT 2006 - 2013 Kepler 2009 - 2013 K2 2013 - 2019 TESS 2018 - 2020++ hello
7. 07 Jun 2021 O. J. Hall Nordic Dynamo seminar Stars with convective envelopes exhibit solar-like oscillations Credit: ESA/Gaia/ DPAC CC By-SA 3.0 IGO
8. 07 Jun 2021 O. J. Hall Nordic Dynamo seminar Stars with convective envelopes exhibit solar-like oscillations
9. 07 Jun 2021 O. J. Hall Nordic Dynamo seminar Convection drives acoustic waves in the interior Credit: Mark Garlick/University of Birmingham
10. 07 Jun 2021 O. J. Hall Nordic Dynamo seminar Convection drives acoustic waves in the interior Credit: Mark Garlick/University of Birmingham
11. 07 Jun 2021 O. J. Hall Nordic Dynamo seminar Credit: asterostep.eu
12. 07 Jun 2021 O. J. Hall Nordic Dynamo seminar Acoustic (Pressure) p-modes Buoyant (Gravity) g-modes Credit: Don Kurtz
13. 07 Jun 2021 O. J. Hall Nordic Dynamo seminar Modes of oscillation even probe the stellar core Credit: asterostep.eu
14. 07 Jun 2021 O. J. Hall Nordic Dynamo seminar
15. 07 Jun 2021 O. J. Hall Nordic Dynamo seminar 2 0 1 2 0 1
16. 07 Jun 2021 O. J. Hall Nordic Dynamo seminar νmax
17. 07 Jun 2021 O. J. Hall Nordic Dynamo seminar < Δν >
18. 07 Jun 2021 O. J. Hall Nordic Dynamo seminar Yu+18 Kepler giants Expecting way more with TESS! (8% mass, 3% radius)
19. 07 Jun 2021 O. J. Hall Nordic Dynamo seminar 2 0 1 2 0 1
20. 07 Jun 2021 O. J. Hall Nordic Dynamo seminar The fine structure and individual frequency spacings tell us about the interior conditions of the star
21. 07 Jun 2021 O. J. Hall Nordic Dynamo seminar Credit: asterostep.eu Evolved stars exhibit “mixed modes”
22. 07 Jun 2021 O. J. Hall Nordic Dynamo seminar Frequency analysis + stellar models = precise ages! Serenelli+17 415 dwarfs Pinsonneault+18 APOKASC-2 - 6000+ giants
23. 07 Jun 2021 O. J. Hall Nordic Dynamo seminar Asteroseismology Mass, Radius, Surface Gravity (and therefore distances) Frequency Analysis Stellar Rotation & Inclination, interior inversion νmax Δν + + Teff Stellar Models Age, Chemical Mixing, Improved Mass, Radius
24. 07 Jun 2021 O. J. Hall Nordic Dynamo seminar Asteroseismology can weigh in on the study of main sequence stellar rotation
25. 07 Jun 2021 O. J. Hall Nordic Dynamo seminar Stellar Rotational Evolution Stellar rotation & colour provide age to ~10% in young stars. - Meibom+2015 (see also Barnes 2007) Gyrochronology is an incredible tool for dating young stars. (see e.g. Curtis et al. 2019, and Hall, Jerabkova + friends in prep!)
26. 07 Jun 2021 O. J. Hall Nordic Dynamo seminar Stellar Rotational Evolution Gyrochronology can not reconcile clusters with asteroseismic ages. - van Saders+2016 (see also Nielsen+2015 Davies+2015 Angus+2015) Figure 1, van Saders+2016
27. 07 Jun 2021 O. J. Hall Nordic Dynamo seminar Stellar Rotational Evolution Figure 1, McQuillan+2014 Is weakened magnetic braking a selection effect…? - van Saders+2019
28. 07 Jun 2021 O. J. Hall Nordic Dynamo seminar Stellar Rotational Evolution Figure 8, van Saders+2019 Is weakened magnetic braking a selection effect…? - van Saders+2019
29. 07 Jun 2021 O. J. Hall Nordic Dynamo seminar 2 0 1 2 1 0 Asteroseismology can measure stellar rotation independently (see e.g. Nielsen et al. 2015, Davies et al. 2015, Benomar et al. 2018) Measuring Asteroseismic Rotation
30. 07 Jun 2021 O. J. Hall Nordic Dynamo seminar Measuring Asteroseismic Rotation
31. 07 Jun 2021 O. J. Hall Nordic Dynamo seminar Period Measuring Asteroseismic Rotation
32. 07 Jun 2021 O. J. Hall Nordic Dynamo seminar Measuring Asteroesismic Rotation Credit: asterostep.eu
33. 07 Jun 2021 O. J. Hall Nordic Dynamo seminar Hall+ 2021 Measuring Asteroseismic Rotation
34. 07 Jun 2021 O. J. Hall Nordic Dynamo seminar A comment on sampling To improve the fitting process, we can sample them in a particular way. Inclination angle and rotational splitting are degenerate Chaplin+Basu 2017
35. 07 Jun 2021 O. J. Hall Nordic Dynamo seminar A comment on sampling To improve the fitting process, we can sample them in a particular way. Inclination angle and rotational splitting are degenerate Davies+2015
36. 07 Jun 2021 O. J. Hall Nordic Dynamo seminar A comment on sampling To improve the fitting process, we can sample them in a particular way. p(cos i) = 𝒰(0,1) - Keaton Bell’s blog has a good breakdown of this! http://keatonb.github.io/ Inclination angle and rotational splitting are degenerate
37. 07 Jun 2021 O. J. Hall Nordic Dynamo seminar Hall+ 2021 Our sample of stars from the Kages and LEGACY catalogues spans up to over 12 Gyr in age (for the seismic modeling, see: Silva Aguirre et al. 2016, Davies et al. 2016 (Kages) Lund et al. (2017), Silva Aguirre et al. (2017) (LEGACY) Measuring Asteroseismic Rotation
38. 07 Jun 2021 O. J. Hall Nordic Dynamo seminar We obtained seismic rotation rates for 91 stars in our sample. For those with spot rotation, both measurements agreed. Measuring Asteroseismic Rotation Hall+ 2021
39. 07 Jun 2021 O. J. Hall Nordic Dynamo seminar Seismology + Gyrochronology Hall+ 2021
40. 07 Jun 2021 O. J. Hall Nordic Dynamo seminar Seismology + Gyrochronology Hall+ 2021
41. 07 Jun 2021 O. J. Hall Nordic Dynamo seminar Ps µ ∑s ∑Ro D æD Standard KDE WMB KDE HBM Mixture Models & Gyrochronology QWMB θL We do this in mass, metallicity, age, temperature and rotation! Hall+ 2021
42. 07 Jun 2021 O. J. Hall Nordic Dynamo seminar HBM Mixture Models & Gyrochronology Hall+ 2021
43. 07 Jun 2021 O. J. Hall Nordic Dynamo seminar Summary ‣ Asteroseismology lets you probe fundamental properties of stars in a (mostly) independent way ‣ We used measured seismic rotation in 91 main sequence oscillators ‣ These rotation rates strongly support the presence of weakened magnetic braking on the main sequence.