asteroseismology; stars: oscillations; stars: rotation; methods: data analysis
Abstract :
[en] A unique type of oscillation modes has recently been identified in γ Doradus variables. These low-frequency modes are called Rossby modes (or r modes) because they consist of Rossby waves in each spherical layer. These waves are characterised by toroidal motions that are restored by the latitudinal variation in the Coriolis force. The horizontal oscillations are weakly coupled in the radial direction. We show that these modes can be used to probe the interior of the stars. The method of the ν - √∆ν diagram, which has originally been developed to analyse another type of modes, Kelvin g-modes (or prograde sectoral g-modes), is extended to take Rossby modes into account. We first show based on a theoretical model and then on two stars, <ASTROBJ>KIC 3240967</ASTROBJ> and <ASTROBJ>KIC 12066947</ASTROBJ>, that the method can be adapted to Rossby modes straightforwardly. In addition, we demonstrate that simultaneous analysis of Kelvin and Rossby modes results in (1) smaller uncertainties in the internal rotation rate and the characteristic period of gravity modes, and (2) a substantial reduction of the correlation between the estimates of the two parameters.
Research center :
STAR - Space sciences, Technologies and Astrophysics Research - ULiège
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Takata, M.; Department of Astronomy, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
Ouazzani, R.-M.; LESIA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, Univ. Paris Diderot, Sorbonne Paris Cité, 5 place Jules Janssen, 92195, Meudon, France
Saio, H.; Astronomical Institute, Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan
Christophe, S.; LESIA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, Univ. Paris Diderot, Sorbonne Paris Cité, 5 place Jules Janssen, 92195, Meudon, France
Ballot, J.; IRAP, Université de Toulouse, CNRS, UPS, CNES, 14 avenue Édouard Belin, 31400, Toulouse, France
Antoci, V.; DTU Space, National Space Institute, Technical University of Denmark, Elektrovej 328, 2800 Kgs., Lyngby, Denmark ; Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, 8000, Aarhus C, Denmark
Salmon, Sébastien ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astrophysique stellaire théorique et astérosismologie
Language :
English
Title :
Inferring the internal structure of γ Doradus variables from Rossby modes. Extension of the ν - √∆ν diagram
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