| Issue |
A&A
Volume 391, Number 3, September I 2002
|
|
|---|---|---|
| Page(s) | 1039 - 1052 | |
| Section | Stellar structure and evolution | |
| DOI | https://doi.org/10.1051/0004-6361:20020806 | |
| Published online | 09 August 2002 | |
The determination of 
for metal-poor A-type stars using 
and 2MASS 
, 
and 
magnitudes
*,**
1
Kitt Peak National Observatory, National Optical Astronomy Observatories, Box 26732, Tucson, AZ 85726-6732, USA
2
Istituto di Astrofisica Spaziale e Fisica Cosmica, CNR, via del Fosso del Cavaliere, 00133 Roma, Italy
3
Osservatorio Astronomico di Trieste, via Tiepolo 11, 34131 Trieste, Italy e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
Corresponding author: T. Kinman, This email address is being protected from spambots. You need JavaScript enabled to view it.
Received:
5
April
2002
Accepted:
27
May
2002
Abstract
Effective temperatures (Teff) can be determined
from 
, 
and 
colours that are derived from 2MASS magnitudes.
This gives another way to estimate the
Teff of faint blue halo stars
(V
15) whose temperatures are now usually deduced from 
.
Transformations (adapted from Carpenter
[CITE]) are used to change colours derived from the 2MASS
data to the Johnson system. Teff is then derived from these colours using
an updated Kurucz model. Tables are given to derive
Teff as a function of , and for a variety of metallicities
and 
suitable for blue horizontal branch and main sequence stars.
The temperatures obtained in this way are compared with those in the recent
literature for various stars with 5 ≤
V
≤ 15 and Teff
in the range 6500 to 9500 K; systematic differences are
~100 K. An exception is the sample of BHB stars observed by
Wilhelm et al. ([CITE]) whose Teff are significantly
cooler than those we derive by an amount that increases with increasing
temperature.
Key words: stars: fundamental parameters (temperatures) / stars: horizontal-branch
NOAO is operated by the Association of Universities for research in Astronomy, Inc., under contract with the National Science Foundation.
Tables 2 and 3 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/391/1039
© ESO, 2002
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