HYBRID {gamma} DORADUS-{delta} SCUTI PULSATORS: NEW INSIGHTS INTO THE PHYSICS OF THE OSCILLATIONS FROM KEPLER OBSERVATIONS
- Institut fuer Astronomie, Tuerkenschanzstr. 17, A-1180 Wien (Austria)
- South African Astronomical Observatory, P.O. Box 9, Observatory 7935 (South Africa)
- INAF-Osservatorio Astrofisico di Catania, Via S. Sofia 78, 95123 Catania (Italy)
- Instytut Astronomiczny, Uniwersytet Wroclawski, Kopernika 11, 51-622 Wroclaw (Poland)
- Los Alamos National Laboratory, X-2 MS T-086, Los Alamos, NM 87545-2345 (United States)
- Jeremiah Horrocks Institute of Astrophysics, University of Central Lancashire, Preston PR1 2HE (United Kingdom)
- INAF-Osservatorio Astronomico di Capodimonte, Via Moiariello 16, 80131 Naples (Italy)
- Laboratorio de Astrofisica Estelar y Exoplanetas, LAEX-CAB (INTA-CSIC), P.O. Box 78, 28691 Villanueva de la Canada, Madrid (Spain)
- Instituto de Astrofisica de AndalucIa (CSIC), CP3004, Granada (Spain)
- Laboratoire AIM, CEA/DSM CNRS-Universite Paris Diderot, IRFU/SAp, Centre de Saclay, 91191 Gif-sur-Yvette Cedex (France)
- NASA Ames Research Center, MS 244-30, Moffett Field, CA 94035 (United States)
- Las Cumbres Observatory Global Telescope, Goleta, CA 93117 (United States)
- Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C (Denmark)
- Space Telescope Science Institute, Baltimore, MD 21218 (United States)
- SETI Institute/NASA Ames Research Center, MS 244-30, Moffett Field, CA 94035 (United States)
Observations of the pulsations of stars can be used to infer their interior structure and test theoretical models. The main-sequence {gamma} Doradus (Dor) and {delta} Scuti (Sct) stars with masses 1.2-2.5 M {sub sun} are particularly useful for these studies. The {gamma} 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 {delta} Sct stars pulsate in low-order g- and p-modes with periods of order 2 hr, driven by the {kappa} 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 {gamma} Dor and {delta} 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 {delta} Sct or {gamma} Dor pulsators, i.e., essentially all of the stars show frequencies in both the {delta} Sct and the {gamma} 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 {delta} Sct, {gamma} Dor, {delta} Sct/{gamma} Dor or {gamma} Dor/{delta} Sct hybrids.
- OSTI ID:
- 21305029
- Journal Information:
- Astrophysical Journal Letters, Vol. 713, Issue 2; Other Information: DOI: 10.1088/2041-8205/713/2/L192; Country of input: International Atomic Energy Agency (IAEA); ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
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