HYBRID γ DORADUS–δ SCUTI PULSATORS: NEW INSIGHTS INTO THE PHYSICS OF THE OSCILLATIONS FROM KEPLER OBSERVATIONS

By A. Grigahcène, V. Antoci, L. Balona, G. Catanzaro, J. Daszyńska-Daszkiewicz, J. Guzik, G. Handler, G. Houdek, D. Kurtz, M. Marconi and 32 more. 2010

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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☉ 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.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/c14f87804e53a2b36b494fdda7cfcde2a029f074

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Citations in the corpus

GYRE: An open-source stellar oscillation code based on a new Magnus Multiple Shooting Scheme (2013, background): “Exciting results from these missions include the discovery that nearly all γ Doradus and δ Scuti stars are hybrid pulsators (Grigahcène et al. 2010); ensemble asteroseismic analysis of solar-like oscillations in hundreds of solar-type stars (Chaplin et al. 2011); and the detection of solar-like…”
REVISED STELLAR PROPERTIES OF KEPLER TARGETS FOR THE QUARTER 1–16 TRANSIT DETECTION RUN (2013, background): “…the application of asteroseismology to stars ranging from hot, compact objects (Kawaler et al. 2010; Østensen et al. 2011), to classical pulsators (Grigahcène et al. 2010; Kolenberg et al. 2010; Kurtz et al. 2011), cool dwarfs (Chaplin et al. 2011; Silva Aguirre et al. 2011; Mathur et al. 2012)…”
The Kepler characterization of the variability among A- and F-type stars I. General overview (2011, methodology): “This result was already hinted atby Grigahcène et al. (2010) and Hareter et al. (2010), but the quantification by means of this sample is remarkable.”