Sign on

SAO/NASA ADS Astronomy Abstract Service

· Find Similar Abstracts (with default settings below)
· Electronic Refereed Journal Article (HTML)
· Full Refereed Journal Article (PDF/Postscript)
· arXiv e-print (arXiv:astro-ph/0003316)
· On-line Data
· References in the article
· Citations to the Article (51) (Citation History)
· Refereed Citations to the Article
· SIMBAD Objects (146)
· Also-Read Articles (Reads History)
·
· Translate This Page
Title:
A Survey for Low-Mass Stars and Brown Dwarfs in the Upper Scorpius OB Association
Authors:
Ardila, David; Martín, Eduardo; Basri, Gibor
Affiliation:
AA(Department of Astronomy, University of California at Berkeley, Berkeley, CA 94720-3411 , ), AB(Division of Geological and Planetary Sciences, MC 150-21, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125; ), AC(Department of Astronomy, University of California at Berkeley, Berkeley, CA 94720-3411 , )
Publication:
The Astronomical Journal, Volume 120, Issue 1, pp. 479-487. (AJ Homepage)
Publication Date:
07/2000
Origin:
UCP
AJ Keywords:
open clusters and associations: individual (Scorpius-Centarus), Stars: Low-Mass, Brown Dwarfs
DOI:
10.1086/301443
Bibliographic Code:
2000AJ....120..479A

Abstract

The Upper Scorpius association is the OB association nearest to the Sun (145 pc). Its young age (~5 Myr) makes it an ideal place to search for low-mass stars and brown dwarfs, as these objects should be relatively bright. We have performed a photometric search for the low-mass members of the association, using the R, I, and Z filters. The completeness limit is I~18.5, and the saturation limit is I~13. We obtain 138 candidate members, covering nearly the entire M spectral type range. We find an excess of brown dwarf candidates over the number predicted by a Miller-Scalo initial mass function. In addition, we have performed infrared imaging and low-resolution optical spectroscopy of selected candidates. We find that the infrared observations confirm the spectral types obtained with the optical photometry. Furthermore, we find Hα in emission in 20 of the 22 objects observed spectroscopically. As Hα is an indicator of youth, we believe that these 20 objects may belong to the association. One of them, UScoCTIO 128, has a very strong and constant Hα line (equivalent width -130 Å), and its position in the color-magnitude diagram suggests that it is a brown dwarf with mass 0.02 Msolar. Confirmation of this and the other candidates will have to wait for higher resolution observations that can reveal spectroscopic mass indicators such as Li I and gravity indicators such as K I and the subordinate lines of Na I.
Bibtex entry for this abstract   Preferred format for this abstract (see Preferences)
   

Find Similar Abstracts:

Use: Authors
Title
Keywords (in text query field)
Abstract Text
Return: Query Results Return    items starting with number
Query Form
Database: Astronomy
Physics
arXiv e-prints