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Projected Rotational Velocities and Stellar Characterization of 350 B Stars in the Nearby Galactic Disk

Braganca, G. A.; Daflon, S.; Cunha, K.; Bensby, Thomas LU ; Oey, M. S. and Walth, G. (2012) In Astronomical Journal 144(5).
Abstract
Projected rotational velocities (v sin i) are presented for a sample of 350 early B-type main-sequence stars in the nearby Galactic disk. The stars are located within similar to 1.5 kpc from the Sun, and the great majority within 700 pc. The analysis is based on high-resolution spectra obtained with the MIKE spectrograph on the Magellan Clay 6.5 m telescope at the Las Campanas Observatory in Chile. Spectral types were estimated based on relative intensities of some key line absorption ratios and comparisons to synthetic spectra. Effective temperatures were estimated from the reddening-free Q index, and projected rotational velocities were then determined via interpolation on a published grid that correlates the synthetic FWHM of the He i... (More)
Projected rotational velocities (v sin i) are presented for a sample of 350 early B-type main-sequence stars in the nearby Galactic disk. The stars are located within similar to 1.5 kpc from the Sun, and the great majority within 700 pc. The analysis is based on high-resolution spectra obtained with the MIKE spectrograph on the Magellan Clay 6.5 m telescope at the Las Campanas Observatory in Chile. Spectral types were estimated based on relative intensities of some key line absorption ratios and comparisons to synthetic spectra. Effective temperatures were estimated from the reddening-free Q index, and projected rotational velocities were then determined via interpolation on a published grid that correlates the synthetic FWHM of the He i lines at 4026, 4388 and 4471 A with v sin i. As the sample has been selected solely on the basis of spectral types, it contains a selection of B stars in the field, in clusters, and in OB associations. The v sin i distribution obtained for the entire sample is found to be essentially flat for v sin i values between 0 and 150 km s(-1), with only a modest peak at low projected rotational velocities. Considering subsamples of stars, there appears to be a gradation in the v sin i distribution with the field stars presenting a larger fraction of the slow rotators and the cluster stars distribution showing an excess of stars with v sin i between 70 and 130 km s(-1). Furthermore, for a subsample of potential runaway stars we find that the v sin i distribution resembles the distribution seen in denser environments, which could suggest that these runaway stars have been subject to dynamical ejection mechanisms. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
stars: early-type, stars: fundamental parameters, stars: rotation
in
Astronomical Journal
volume
144
issue
5
publisher
The American Astronomical Society
external identifiers
  • wos:000310530400006
  • scopus:84867286769
ISSN
1538-3881
DOI
10.1088/0004-6256/144/5/130
language
English
LU publication?
yes
id
30024d6f-5030-4d58-b126-52fbfb4c5b5a (old id 3283478)
alternative location
http://arxiv.org/abs/1208.1674
date added to LUP
2012-12-20 12:11:38
date last changed
2017-10-22 03:17:23
@article{30024d6f-5030-4d58-b126-52fbfb4c5b5a,
  abstract     = {Projected rotational velocities (v sin i) are presented for a sample of 350 early B-type main-sequence stars in the nearby Galactic disk. The stars are located within similar to 1.5 kpc from the Sun, and the great majority within 700 pc. The analysis is based on high-resolution spectra obtained with the MIKE spectrograph on the Magellan Clay 6.5 m telescope at the Las Campanas Observatory in Chile. Spectral types were estimated based on relative intensities of some key line absorption ratios and comparisons to synthetic spectra. Effective temperatures were estimated from the reddening-free Q index, and projected rotational velocities were then determined via interpolation on a published grid that correlates the synthetic FWHM of the He i lines at 4026, 4388 and 4471 A with v sin i. As the sample has been selected solely on the basis of spectral types, it contains a selection of B stars in the field, in clusters, and in OB associations. The v sin i distribution obtained for the entire sample is found to be essentially flat for v sin i values between 0 and 150 km s(-1), with only a modest peak at low projected rotational velocities. Considering subsamples of stars, there appears to be a gradation in the v sin i distribution with the field stars presenting a larger fraction of the slow rotators and the cluster stars distribution showing an excess of stars with v sin i between 70 and 130 km s(-1). Furthermore, for a subsample of potential runaway stars we find that the v sin i distribution resembles the distribution seen in denser environments, which could suggest that these runaway stars have been subject to dynamical ejection mechanisms.},
  articleno    = {130},
  author       = {Braganca, G. A. and Daflon, S. and Cunha, K. and Bensby, Thomas and Oey, M. S. and Walth, G.},
  issn         = {1538-3881},
  keyword      = {stars: early-type,stars: fundamental parameters,stars: rotation},
  language     = {eng},
  number       = {5},
  publisher    = {The American Astronomical Society},
  series       = {Astronomical Journal},
  title        = {Projected Rotational Velocities and Stellar Characterization of 350 B Stars in the Nearby Galactic Disk},
  url          = {http://dx.doi.org/10.1088/0004-6256/144/5/130},
  volume       = {144},
  year         = {2012},
}