Bibcode
Grigahcène, A.; Antoci, V.; Balona, L.; Catanzaro, G.; Daszyńska-Daszkiewicz, J.; Guzik, J. A.; Handler, G.; Houdek, G.; Kurtz, D. W.; Marconi, M.; Monteiro, M. J. P. F. G.; Moya, A.; Ripepi, V.; Suárez, J.-C.; Uytterhoeven, K.; Borucki, W. J.; Brown, T. M.; Christensen-Dalsgaard, J.; Gilliland, R. L.; Jenkins, J. M.; Kjeldsen, H.; Koch, D.; Bernabei, S.; Bradley, P.; Breger, M.; Di Criscienzo, M.; Dupret, M.-A.; García, R. A.; García Hernández, A.; Jackiewicz, J.; Kaiser, A.; Lehmann, H.; Martín-Ruiz, S.; Mathias, P.; Molenda-Żakowicz, J.; Nemec, J. M.; Nuspl, J.; Paparó, M.; Roth, M.; Szabó, R.; Suran, M. D.; Ventura, R.
Bibliographical reference
The Astrophysical Journal Letters, Volume 713, Issue 2, pp. L192-L197 (2010).
Advertised on:
4
2010
Citations
218
Refereed citations
176
Description
Observations of the pulsations of stars can be used to infer their
interior structure and test theoretical models. The main-sequence
γ Doradus (Dor) and δ Scuti (Sct) stars with masses 1.2-2.5
M sun are particularly useful for these studies. The γ
Dor stars pulsate in high-order g-modes with periods of order 1 day,
driven by convective blocking at the base of their envelope convection
zone. The δ Sct stars pulsate in low-order g- and p-modes with
periods of order 2 hr, driven by the κ mechanism operating in the
He II ionization zone. Theory predicts an overlap region in the
Hertzsprung-Russell diagram between instability regions, where "hybrid"
stars pulsating in both types of modes should exist. The two types of
modes with properties governed by different portions of the stellar
interior provide complementary model constraints. Among the known
γ Dor and δ Sct stars, only four have been confirmed as
hybrids. Now, analysis of combined Quarter 0 and Quarter 1 Kepler data
for hundreds of variable stars shows that the frequency spectra are so
rich that there are practically no pure δ Sct or γ Dor
pulsators, i.e., essentially all of the stars show frequencies in both
the δ Sct and the γ Dor frequency range. A new observational
classification scheme is proposed that takes into account the amplitude
as well as the frequency and is applied to categorize 234 stars as
δ Sct, γ Dor, δ Sct/γ Dor or γ Dor/δ
Sct hybrids.