Detection of Solar-like Oscillations, Observational Constraints, and Stellar Models for θ Cyg, the Brightest Star Observed By the Kepler Mission

Guzik, J. A. and Houdek, G. and Chaplin, W. J. and Smalley, B. and Kurtz, D. W. and Gilliland, R. L. and Mullally, F. and Rowe, J. F. and Bryson, S. T. and Still, M. D. and Antoci, V. and Appourchaux, T. and Basu, S. and Bedding, T. R. and Benomar, O. and Garcia, R. A. and Huber, D. and Kjeldsen, H. and Latham, D. W. and Metcalfe, T. S. and Papics, P. I. and White, T. R. and Aerts, C. and Ballot, J. and Boyajian, T. S. and Briquet, M. and Bruntt, H. and Buchhave, L. A. and Campante, T. L. and Catanzaro, G. and Christensen-Dalsgaard, J. and Davies, G. R. and Dogan, G. and Dragomir, D. and Doyle, A. P. and Elsworth, Y. and Frasca, A. and Gaulme, P. and Gruberbauer, M. and Handberg, R. and Hekker, S. and Karoff, C. and Lehmann, H. and Mathias, P. and Mathur, S. and Miglio, A. and Molenda-Zakowicz, J. and Mosser, B. and Murphy, S. J. and Regulo, C. and Ripepi, V. and Salabert, D. and Sousa, S. G. and Stello, D. and Uytterhoeven, K. (2016) Detection of Solar-like Oscillations, Observational Constraints, and Stellar Models for θ Cyg, the Brightest Star Observed By the Kepler Mission. The Astrophysical Journal, 831 (1):17. pp. 171-22. ISSN 1538-4357

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θ Cygni is an F3 spectral type magnitude V = 4.48 main-sequence star that was the brightest star observed by the original Kepler spacecraft mission. Short-cadence (58.8 s) photometric data using a custom aperture were first obtained during Quarter 6 (2010 June–September) and subsequently in Quarters 8 and 12–17. We present analyses of solar-like oscillations based on Q6 and Q8 data, identifying angular degree l = 0, 1, and 2 modes with frequencies of 1000–2700 μHz, a large frequency separation of 83.9 ± 0.4 μHz, and maximum oscillation amplitude at frequency νmax = 1829 ± 54 μHz. We also present analyses of new ground-based spectroscopic observations, which, combined with interferometric angular diameter measurements, give Teff = 6697 ± 78 K, radius 1.49 ± 0.03 R⊙, [Fe/H] = −0.02 ± 0.06 dex, and log g = 4.23 ± 0.03. We calculate stellar models matching these constraints using the Yale Rotating Evolution Code and the Asteroseismic Modeling Portal. The best-fit models have masses of 1.35–1.39 M⊙ and ages of 1.0–1.6 Gyr. θ Cyg's Teff and log g place it cooler than the red edge of the γ Doradus instability region established from pre-Kepler ground-based observations, but just at the red edge derived from pulsation modeling. The pulsation models show γ Dor gravity modes driven by the convective blocking mechanism, with frequencies of 1–3 cycles per day (11 to 33 μHz). However, gravity modes were not seen in Kepler data; one signal at 1.776 cycles per day (20.56 μHz) may be attributable to a faint, possibly background, binary.

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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: File reproduced in accordance with the copyright policy of the publisher/author.
Faculty/School / Institute/Centre: No Faculty
Faculty/School / Institute/Centre: No Faculty
Date Deposited: 28 Apr 2022 01:26
Last Modified: 30 May 2022 23:24
Uncontrolled Keywords: asteroseismology; stars: fundamental parameters; stars: interiors; stars: solar-type; Astrophysics - Solar and Stellar Astrophysics
Fields of Research (2020): 51 PHYSICAL SCIENCES > 5101 Astronomical sciences > 510109 Stellar astronomy and planetary systems
Socio-Economic Objectives (2020): 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280120 Expanding knowledge in the physical sciences
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