000006246 001__ 6246
000006246 005__ 20230127151338.0
000006246 0247_ $$2DOI$$a10.1051/0004-6361/202243507
000006246 037__ $$aSCART-2023-0101
000006246 100__ $$aSamadi-Ghadim, A.
000006246 245__ $$aKIC 6951642: A confirmed Kepler gamma Doradus - delta Scuti star with intermediate to fast rotation in a possible single-lined binary system
000006246 260__ $$c2022
000006246 500__ $$aeprint: arXiv:2209.04651
000006246 520__ $$aKIC 6951642 has been reported as a candidate hybrid pulsator of type-γ Doradus - δ Scuti from observations of the first quarters of the Kepler mission. The regular patterns seen in the Fourier spectra of the Kepler and Transiting Exoplanet Survey Satellite (TESS) light curves and the sinusoidal modulation of its surface brightness suggest the additional presence of rotational modulation and stellar activity, respectively.  We aim to investigate the pulsating nature of KIC 6951642 and to search for the signature of rotation and/or activity in the light curves.  We performed an iterative frequency search of both Fourier spectra, and searched for regular patterns in them. We applied spectrum synthesis to determine the atmospheric stellar parameters. Since KIC 6951642 was reported to belong to a spectroscopic binary system, we fitted the time delays derived from the light curves with the radial velocities obtained from published as well as new spectra in an attempt to improve the quality of the first orbit.  Follow-up spectroscopy showed that KIC 6951642 is a fast-rotating F0-type star in a possible single-lined binary with a period of about 4.8 yr. In the low-frequency regime, we identified the frequencies of 0.721 d^-1 as well as of 0.0087 d^-1. We attribute the first frequency to stellar rotation, and the second one to stellar activity with a cycle of length of 3.2 yr. We also detected g modes, with the strongest mode located at 2.238 d^-1, as well as three asymmetric multiplets (with a mean spacing of 0.675 +/- 0.044 d^-1). In the high-frequency regime, we detected frequencies of type delta Scuti, with the strongest mode located at 13.96 d^-1, as well as seven asymmetric multiplets (with a mean spacing of 0.665 +/- 0.084 d^-1). We subsequently identified a few more frequencies that appear to be combinations of a g or p mode and one of the higher cited frequencies not due to pulsations.  We propose that KIC 6951642 accomodates a fast-rotating gamma Dor - delta Sct hybrid star with various rotationally split multiplets of g and p modes and that it also displays a cycle lasting years of (possible) stellar activity.
000006246 594__ $$aNO
000006246 6531_ $$aAsteroseismology
000006246 6531_ $$atechniques: photometric
000006246 6531_ $$astars: variables: delta Scuti
000006246 6531_ $$astars: rotation
000006246 6531_ $$astars: activity
000006246 6531_ $$abinaries: spectroscopic
000006246 6531_ $$aAstrophysics - Solar and Stellar Astrophysics
000006246 6531_ $$aAstrophysics - Instrumentation and Methods for Astrophysics
000006246 700__ $$aLampens, P.
000006246 700__ $$aGizon, L.
000006246 773__ $$cA60$$pAstronomy & Astrophysics$$v667$$y2022
000006246 8560_ $$fpatricia.lampens@observatoire.be
000006246 85642 $$ahttps://ui.adsabs.harvard.edu/abs/2022A&A...667A..60S
000006246 905__ $$apublished in
000006246 980__ $$aREFERD