期刊
ASTROPHYSICAL JOURNAL LETTERS
卷 808, 期 1, 页码 -出版社
IOP PUBLISHING LTD
DOI: 10.1088/2041-8205/808/1/L31
关键词
convection; line: profiles; stars: evolution; stars: massive; stars: oscillations; turbulence
资金
- Alexander-von-Humboldt foundation
- Spanish Ministry of Economy and Competitiveness (MINECO) [AYA2010-21697-C05-04, AYA2012-39364-C02-01]
- Severo Ochoa [SEV-2011-0187]
The major mass fraction of the envelope of hot luminous stars is radiatively stable. However, the partial ionization of hydrogen, helium, and iron gives rise to extended sub-surface convection zones in all of them. In this work, we investigate the effect of the pressure induced by the turbulent motion in these zones based on the mixing-length theory, and we search for observable consequences. We find that the turbulent pressure fraction can amount up to similar to 5% in OB supergiants and up to similar to 30% in cooler supergiants. The resulting structural changes are, however, not significantly affecting the evolutionary tracks compared to previous calculations. Instead, a comparison of macroturbulent velocities derived from high-quality spectra of OB stars with the turbulent pressure fraction obtained in corresponding stellar models reveals a strong correlation between these two quantities. We discuss a possible physical connection and conclude that turbulent pressure fluctuations may drive high-order oscillations, which-as conjectured earlier-manifest themselves as macroturbulence in the photospheres of hot luminous stars.
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