Period spacings of γ Doradus pulsators in the Kepler field: Rossby and gravity modes in 82 stars

Li, Gang and Van Reeth, Timothy and Bedding, Timothy R. and Murphy, Simon J. and Antoci, Victoria (2019) Period spacings of γ Doradus pulsators in the Kepler field: Rossby and gravity modes in 82 stars. Monthly Notices of the Royal Astronomical Society, 487 (1). pp. 782-800. ISSN 0035-8711

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Abstract

Rossby modes are the oscillations in a rotating fluid, whose restoring force is the Coriolis force. They provide an additional diagnostic to understand the rotation of stars, which complicates asteroseismic modelling. We report 82 γ Doradus stars for which clear period spacing patterns of both gravity and Rossby modes have been detected. The period spacings of both show a quasi-linear relation with the pulsation period, but the slope is negative for the gravity modes and positive for the Rossby modes. Most Rossby modes have k = −2, m = −1. For only one star, a series of k = −1, m = −1 modes is seen. For each pattern, the mean pulsation period, the mean period spacing, and the slope are measured. We find that the slope correlates with the mean period for Rossby mode patterns. The traditional approximation of rotation is used to measure the near-core rotation rate, assuming the star rotates rigidly. We report the near-core rotation rates, the asymptotic period spacings, and the radial orders of excited modes of these 82 main-sequence stars. The near-core rotation rates lie between 0.6 and 2.3d−1⁠. Six stars show surface rotation modulations, among which only KIC 3341457 shows differential rotation, whilst the other five stars have uniform rotations. The radial orders of excited modes show different distributions for the dipole and quadrupole gravity modes versus the Rossby modes.


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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: 14 Jul 2022 03:53
Last Modified: 17 Jul 2022 23:54
Uncontrolled Keywords: stars: oscillations; stars: rotation; stars: variables; 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
Identification Number or DOI: https://doi.org/10.1093/mnras/stz1171
URI: http://eprints.usq.edu.au/id/eprint/47900

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