Twelve new substellar members in Taurus. Clues for substellar formation models
✍ Scribed by S. Guieu; J.-L. Monin; C. Dougados; E. Magnier; E. L. Martín
- Publisher
- John Wiley and Sons
- Year
- 2005
- Tongue
- English
- Weight
- 115 KB
- Volume
- 326
- Category
- Article
- ISSN
- 0004-6337
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✦ Synopsis
Abstract
Recent studies of the substellar population in the Taurus cloud have revealed a deficit of brown dwarfs compared to the Trapezium cluster population (Briceño et al. 1998; Luhman 2000; Luhman et al. 2003a; Luhman 2004) However, these works have concentrated on the highest stellar density regions of the Taurus cloud. We have performed a large scale optical survey of this region, covering a total area of ≃ 28 deg^2^, and encompassing the densest parts of the cloud as well as their surroundings. In this paper, we present optical spectroscopic follow‐up observations of 97 photometrically selected potential new low‐mass Taurus members. We derive spectral types, visual absorption and luminosity class estimates and discuss our criteria to assess Taurus membership. These observations reveal 5 new very low‐mass stars (VLMs) and 12 new Brown Dwarfs (BDs) on the Taurus cloud. We derive a new substellar to stellar ratio in Taurus of ℛ~ss~ = 0.23 ± 0.05. This revisited ratio appears consistent with the value of 0.26 ± 0.04 previously derived in the Trapezium cluster under similar assumptions. We find indications that the relative numbers of BDs with respect to stars is decreased by a factor 2 in the central regions of the aggregates with respect to the more distributed population. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)