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A representative sample of Be stars II. K band spectroscopy

Clark, J. S. and Steele, I. A. (2000). A representative sample of Be stars II. K band spectroscopy. Astronomy and Astrophysics Supplement Series, 141(1/Janu) pp. 65–77.

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DOI (Digital Object Identifier) Link: http://dx.doi.org/10.1051/aas:2000310
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Abstract

We present K band (2.05 m - 2.22 m) spectra of 66 isolated Be stars of spectral types O9-B9 and luminosity classes III, IV & V. We find that objects with He I features either in emission or absorption are B3 or earlier. Objects with Mg II emission but no He I are B2 to B4, while objects with Br emission but no evidence of He I or Mg II are B5 or later. Na I emission in the spectra of 4 objects appears to indicate that regions of the circumstellar envelopes of these stars must be shielded from direct stellar radiation. Systematic trends in the line strength and profile of Br are seen from early to late spectral types which can be understood in terms of differences in the disc temperature and density. 30 per-cent of the stars do not currently show evidence for line emission. Compared to the emission line stars these objects have a significantly lower mean rotational velocity and a distribution of spectral types that is significantly earlier. This can be explained either as the original misidentification of these objects as Be stars (i.e. they never had line emission), or as evidence that stars with lower rotational velocities may be more prone to changes between the Be and B phases.

Item Type: Journal Article
Copyright Holders: 2000 ESO
ISSN: 1286-4846
Keywords: Stars; Emission-line stars; Be stars; Infrared stars; Stars
Academic Unit/Department: Science > Physical Sciences
Interdisciplinary Research Centre: Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR)
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Item ID: 14919
Depositing User: Astrid Peterkin
Date Deposited: 19 Feb 2009 12:02
Last Modified: 30 Jan 2014 04:57
URI: http://oro.open.ac.uk/id/eprint/14919
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