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

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.
Authors:
; ; ; ;  [1] ;  [2] ;  [3] ;  [4] ;  [5]
  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)
  5. Sydney Institute for Astronomy (SIfA), School of Physics, University of Sydney, Sydney, NSW 2006 (Australia)
Publication Date:
OSTI Identifier:
22370133
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 796; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CONVECTION; DISTURBANCES; EXCITATION; HYDROGEN; IONIZATION; LIFETIME; OPACITY; OSCILLATIONS; PERTURBATION THEORY; PULSATIONS; SPECTRA; STARS; STOCHASTIC PROCESSES; STRESSES