Asteroseismology of the Nearby K Dwarf σ Draconis Using the Keck Planet Finder and TESS
Marc Hon, Daniel Huber, Yaguang Li, Τ. S. Metcalfe, T. R. Bedding, J. M. Joel Ong, Ashley Chontos, Ryan A. Rubenzahl, Samuel Halverson, R. A. García, H. Kjeldsen, Dennis Stello, Daniel Hey, T. L. Campante, Andrew W. Howard, Steven R. Gibson, Kodi Rider, Arpita Roy, Ashley Baker, Jerry Edelstein, Chris Smith, Benjamin J. Fulton, Josh Walawender, Max Brodheim, Matthew A. Brown, Dwight Chan, Fei Dai, William Deich, Colby Gottschalk, Jason Grillo, Dave Hale, Grant M. Hill, B. Holden, Aaron Householder, Howard Isaacson, Yuzo Ishikawa, Sharon R. Jelinsky, Marc Kassis, Stephen Kaye, Russ R. Laher, Kyle Lanclos, Chien‐Hsiu Lee, Scott Lilley, Ben McCarney, Timothy N. Miller, Joel Payne, Erik A. Petigura, Claire Poppett, Michael Raffanti, Constance M. Rockosi, Dale Sanford, Christian Schwab, Abby P. Shaum, Martin M. Sirk, Roger M. Smith, J. R. Thorne, John Valliant, Adam Vandenberg, Shin Ywan Wang, Edward Wishnow, T. Wold, Sherry Yeh, Ashley Baker, Sarbani Basu, Megan Bedell, H. M. Cegla, Ian J. M. Crossfield, Courtney D. Dressing, X. Dumusque, Heather A. Knutson, Dimitri Mawet, John M. O’Meara, Guðmundur Stefánsson, Johanna Teske, Gautam Vasisht, Sharon X. Wang, Lauren M. Weiss, Joshua N. Winn, Jason T. Wright
Abstract
Abstract Asteroseismology of dwarf stars cooler than the Sun is very challenging owing to the low amplitudes and rapid timescales of oscillations. Here we present the asteroseismic detection of solar-like oscillations at 4-minute timescales ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mi>ν</mml:mi> <mml:mi>max</mml:mi> </mml:msub> <mml:mo>∼</mml:mo> <mml:mn>4300</mml:mn> </mml:math> μ Hz) in the nearby K dwarf σ Draconis using extreme-precision Doppler velocity observations from the Keck Planet Finder and 20 s cadence photometry from NASA’s Transiting Exoplanet Survey Satellite. The star is the coolest dwarf star to date with both velocity and luminosity observations of solar-like oscillations, having amplitudes of 5.9 ± 0.8 cm s −1 and 0.8 ± 0.2 ppm, respectively. These measured values are in excellent agreement with established luminosity−velocity amplitude relations for oscillations and provide further evidence that mode amplitudes for stars with T eff < 5500 K diminish in scale following an ( L / M ) 1.5 relation. By modeling the star’s oscillation frequencies from photometric data, we measure an asteroseismic age of 4.5 ± 0.9 (ran) ± 1.2 (sys) Gyr. The observations demonstrate the capability of next-generation spectrographs and precise space-based photometry to extend observational asteroseismology to nearby cool dwarfs, which are benchmarks for stellar astrophysics and prime targets for directly imaging planets using future space-based telescopes.