Intrinsic spectral blueshifts in rapidly rotating stars?
Författare
Summary, in English
Spectroscopic radial velocities for several nearby open clusters suggestthat spectra of (especially earlier-type) rapidly rotating stars aresystematically blueshifted by 3 km s<SUP>-1</SUP> or more, relative tothe spectra of slowly rotating ones. Comparisons with astrometricallydetermined radial motions in the Hyades suggests this to be an absoluteblueshift, relative to wavelengths naively expected from stellar radialmotion and gravitational redshift. Analogous trends are seen also inmost other clusters studied (Pleiades, Coma Berenices, Praesepe, alphaPersei, IC 2391, NGC 6475, IC 4665, NGC 1976 and NGC 2516). Possiblemechanisms are discussed, including photospheric convection, stellarpulsation, meridional circulation, and shock-wave propagation, as wellas effects caused by template mismatch in determining wavelengthdisplacements. For early-type stars, a plausible mechanism is shock-wavepropagation upward through the photospheric line-forming regions. Suchwavelength shifts thus permit studies of certain types of stellaratmospheric dynamics and - irrespective of their cause - may influencededuced open-cluster membership (when selected from common velocity) anddeduced cluster dynamics (some types of stars might show fortuitousvelocity patterns).
Avdelning/ar
Publiceringsår
2003
Språk
Engelska
Sidor
581-586
Publikation/Tidskrift/Serie
Astronomy & Astrophysics
Volym
411
Issue
3
Fulltext
- Available as PDF - 637 kB
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Dokumenttyp
Artikel i tidskrift
Förlag
EDP Sciences
Ämne
- Astronomy, Astrophysics and Cosmology
Nyckelord
- methods: data analysis
- techniques: astrometry
- spectroscopy
- radial velocities
- stars: rotation
- open clusters and associations: general
Status
Published
ISBN/ISSN/Övrigt
- ISSN: 0004-6361