The role of turbulent pressure as a coherent pulsational driving mechanism: the case of the δ Scuti star HD 187547

Journal Article · Mon Dec 01 04:00:00 EST 2014 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/796/2/118· OSTI ID:22370133

Antoci, V.; Houdek, G.; Kjeldsen, H.; Trampedach, R.; Arentoft, T. ^[1]; Cunha, M. ^[2]; Handler, G. ^[3]; Lüftinger, T. ^[4]

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1. Stellar Astrophysics Centre, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark)
2. Centro de Astrofísca e Faculdade de Ciências, Universidade do Porto, Rua das Estrelas 4150-762 (Portugal)
3. Copernicus Astronomical Center, Bartycka 18, 00-716 Warsaw (Poland)
4. Institute for Astronomy, University of Vienna, Türkenschanzstr. 17, A-1180 Vienna (Austria)

HD 187547 was the first candidate that led to the suggestion that solar-like oscillations are present in δ Scuti stars. Longer observations, however, show that the modes interpreted as solar-like oscillations have either very long mode lifetimes, longer than 960 days, or are coherent. These results are incompatible with the nature of 'pure' stochastic excitation as observed in solar-like stars. Nonetheless, one point is certain: the opacity mechanism alone cannot explain the oscillation spectrum of HD 187547. Here we present new theoretical investigations showing that convection dynamics can intrinsically excite coherent pulsations in the chemically peculiar δ Scuti star HD 187547. More precisely, it is the perturbations of the mean Reynold stresses (turbulent pressure) that drives the pulsations and the excitation takes place predominantly in the hydrogen ionization zone.

• OSTI ID: 22370133
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 796; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
CONVECTION
DISTURBANCES
EXCITATION
HYDROGEN
IONIZATION
LIFETIME
OPACITY
OSCILLATIONS
PERTURBATION THEORY
PULSATIONS
SPECTRA
STARS
STOCHASTIC PROCESSES
STRESSES