Gravity-mode period spacings and near-core rotation rates of 611 γ Doradus stars with Kepler

Li, Gang and Van Reeth, Timothy and Bedding, Timothy R. and Murphy, Simon J. and Antoci, Victoria and Ouazzani, Rhita-Maria and Barbara, Nicholas H. (2020) Gravity-mode period spacings and near-core rotation rates of 611 γ Doradus stars with Kepler. Monthly Notices of the Royal Astronomical Society, 491 (3). pp. 3586-3605. ISSN 0035-8711

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We report our survey of γ Dor stars from the 4-yr Kepler mission. These stars pulsate mainly in g modes and r modes, showing period-spacing patterns in the amplitude spectra. The period-spacing patterns are sensitive to the chemical composition gradients and the near-core rotation, hence they are essential for understanding the stellar interior. We identified period-spacing patterns in 611 γ Dor stars. Almost every star pulsates in dipole g modes, while about 30 per cent of stars also show clear patterns for quadrupole g modes and 16 per cent of stars present r-mode patterns. We measure periods, period spacings, and the gradient of the period spacings. These three observables guide the mode identifications and can be used to estimate the near-core rotation rate. We find many stars are hotter and show longer period-spacing patterns than theory. Using the traditional approximation of rotation (TAR), we inferred the asymptotic spacings, the near-core rotation rates, and the radial orders of the g and r modes. Most stars have a near-core rotation rate around 1 d−1 and an asymptotic spacing around 4000 s. We also find that many stars rotate more slowly than predicted by theory for unclear reasons. 11 stars show rotational splittings with fast rotation rates. We compared the observed slope–rotation relation with the theory and find a large spread. We detected rotational modulations in 58 stars and used them to derive the core-to-surface rotation ratios. The interiors rotate faster than the cores in most stars, but by no more than 5 per cent.

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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: 13 Jul 2022 23:56
Last Modified: 18 Jul 2022 02:02
Uncontrolled Keywords: stars: oscillations; stars: rotation; 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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