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The Kepler characterization of the variability amongst A- and F-type stars. I. General overview | | K. Uytterhoeven
; A. Moya
; A. Grigahcene
; J.A. Guzik
; J. Gutierrez-Soto
; B. Smalley
; G. Handler
; L.A. Balona
; E. Niemczura
; L. Fox Machado
; S. Benatti
; E. Chapellier
; A. Tkachenko
; R. Szabo
; J.C. Suarez
; V. Ripepi
; J. Pascual
; P. Mathias
; S. Martin-Ruiz
; H. Lehmann
; J. Jackiewicz
; S. Hekker
; M. Gruberbauer
; R.A. Garcia
; X. Dumusque
; D. Diaz-Fraile
; P. Bradley
; V. Antoci
; M. Roth
; B. Leroy
; S.J. Murphy
; P. De Cat
; J. Cuypers
; H. Kjeldsen
; J. Christensen-Dalsgaard
; M. Breger
; A. Pigulski
; L.L. Kiss
; M. Still
; S.E. Thompson
; J. Van Cleve
; | | Date: |
1 Jul 2011 | | Abstract: | The Kepler spacecraft is providing time series of photometric data with
micromagnitude precision for hundreds of A-F type stars. We present a first
general characterization of the pulsational behaviour of A-F type stars as
observed in the Kepler light curves of a sample of 750 candidate A-F type
stars. We propose three main groups to describe the observed variety in
pulsating A-F type stars: gamma Dor, delta Sct, and hybrid stars. We assign 63%
of our sample to one of the three groups, and identify the remaining part as
rotationally modulated/active stars, binaries, stars of different spectral
type, or stars that show no clear periodic variability. 23% of the stars (171
stars) are hybrid stars, which is a much larger fraction than what has been
observed before. We characterize for the first time a large number of A-F type
stars (475 stars) in terms of number of detected frequencies, frequency range,
and typical pulsation amplitudes. The majority of hybrid stars show frequencies
with all kinds of periodicities within the gamma Dor and delta Sct range, also
between 5 and 10 c/d, which is a challenge for the current models. We find
indications for the existence of delta Sct and gamma Dor stars beyond the edges
of the current observational instability strips. The hybrid stars occupy the
entire region within the delta Sct and gamma Dor instability strips, and
beyond. Non-variable stars seem to exist within the instability strips. The
location of gamma Dor and delta Sct classes in the (Teff,logg)-diagram has been
extended. We investigate two newly constructed variables ’efficiency’ and
’energy’ as a means to explore the relation between gamma Dor and delta Sct
stars. Our results suggest a revision of the current observational instability
strips, and imply an investigation of other pulsation mechanisms to supplement
the kappa mechanism and convective blocking effect to drive hybrid pulsations. | | Source: | arXiv, 1107.0335 | | Services: | Forum | Review | PDF | Favorites | |
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