M. Hon, D. Huber, Y. Li, T. S. Metcalfe, T. R. Bedding, J. M. J. Ong, A. Chontos, R. A. Rubenzahl, S. Halverson, R. A. Garcia, H. Kjeldsen, D. Stello, D. R. Hey, T. L. Campante, A. W. Howard, S. R. Gibson, K. Rider, A. Roy, A. D. Baker, J. Edelstein, C. Smith, B. J. Fulton, J. Walawender, M. Brodheim, M. Brown, D. Chan, F. Dai, W. Deich, C. Gottschalk, J. Grillo, D. Hale, G. M. Hill, B. Holden, A. Householder, H. Isaacson, Y. Ishikawa, S. R. Jelinsky, M. Kassis, S. Kaye, R. Laher, K. Lanclos, C.-H. Lee, S. Lilley, B. McCarney, T. N. Miller, J. Payne, E. Petigura, C. Poppett, M. Raffanti, C. M. Rockosi, D. Sanford, C. Schwab, A. P. Shaum, M. M. Sirk, R. Smith, J. Thorne, J. Valliant, A. Vandenberg, S. Y. Wang, E. Wishnow, T. Wold, S. Yeh, A. J. Baker, S. Basu, M. Bedell, H. M. Cegla, I. J. M. Crossfield, C. D. Dressing, X. Dumusque, H. A. Knutson, D. Mawet, J. O'Meara, G. Stefánsson, J. Teske, G. Vasisht, S. X. Wang, L. M. Weiss, J. N. Winn, J. T. Wright
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 ( νmax∼4300 μHz)) 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 Teff < 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.
Keywords
Asteroseismology; Radial velocity; Stellar oscillations; K dwarf stars
The Astrophysical Journal
Volume 975, Number 1
2024 November
