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/0603382)
· References in the article
· Citations to the Article (22) (Citation History)
· Refereed Citations to the Article
· SIMBAD Objects (12)
· Also-Read Articles (Reads History)
·
· Translate This Page
Title:
Discovery of the Coolest Extreme Subdwarf
Authors:
Burgasser, Adam J.; Kirkpatrick, J. Davy
Affiliation:
AA(Massachusetts Institute of Technology, Kavli Institute for Astrophysics and Space Research, Building 37, Room 664B, 77 Massachusetts Avenue, Cambridge, MA 02139; ), AB(Infrared Processing and Analysis Center, M/S 100-22, California Institute of Technology, Pasadena, CA 91125; )
Publication:
The Astrophysical Journal, Volume 645, Issue 2, pp. 1485-1497. (ApJ Homepage)
Publication Date:
07/2006
Origin:
UCP
ApJ Keywords:
Stars: Chemically Peculiar, stars: individual (LEHPM 2-59), stars: individual (APMPM J0559-2903), Stars: Low-Mass, Brown Dwarfs, Stars: Subdwarfs
DOI:
10.1086/504375
Bibliographic Code:
2006ApJ...645.1485B

Abstract

We report the discovery of LEHPM 2-59 as the coolest extreme M subdwarf (esdM) found to date. Optical and near-infrared spectroscopy demonstrate that this source is of later spectral type than the esdM7 APMPM J0559-2903, with the presence of strong alkali lines (including Rb I), VO absorption at 7400 Å, and H2O absorption at 1.4 μm. Current optical classification schemes yield a spectral type of esdM8, making LEHPM 2-59 one of only two ultracool esdMs known. The substantial space velocity of this object (Vgalactic~-180 km s-1) identifies it as a halo star. Spectral model fits to the optical and near-infrared spectral data for this and four other late-type esdMs indicate that LEHPM 2-59 is the coolest esdM currently known, with Teff=2800-3000 K and -1.5<~[M/H]<~-2.0. Comparison of Teff determinations for M dwarfs and esdMs based on spectral model fits from this study and the literature demonstrate a divergence in Teff scales beyond spectral types ~M5/esdM5, as large as 600-800 K by types M8/esdM8. While this divergence is likely an artifact of the underlying classification scheme, it may lead to systematic errors in the derived properties of intermediate metallicity subdwarfs. We comment on the future of ultracool subdwarf classification and suggest several ideas for addressing shortcomings in current (largely extrapolated) schemes.
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