Abstract
We derive projected rotational velocities (v sin i) for a sample of 156 Galactic OB star members of 35 clusters, H II regions, and associations. The He i lines at 4026, 4388, and 4471 Â were analyzed in order to define a calibration of the synthetic He I full widths at half-maximum (FWHMs) versus stellar v sin i. A grid of synthetic spectra of He I line profiles was calculated in non-LTE using an extensive helium model atom and updated atomic data. The v sin i values for all stars were derived using the He I FWHM calibrations, but also, for those target stars with relatively sharp lines, v sin i values were obtained from best-fit synthetic spectra of up to 40 lines of C II, N II, O II, Al III, Mg II, Si III, and S III. This calibration is a useful and efficient tool for estimating the projected rotational velocities of O9-B5 mainsequence stars. The distribution of v sin i for an unbiased sample of early B stars in the unbound association Cep OB2 is consistent with the distribution reported elsewhere for other unbound associations.
Original language | English (US) |
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Pages (from-to) | 1570-1578 |
Number of pages | 9 |
Journal | Astronomical Journal |
Volume | 134 |
Issue number | 4 |
DOIs | |
State | Published - 2007 |
Externally published | Yes |
Keywords
- Line: profiles
- Stars: early-type
- Stars: rotation
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science