Carbon stars and C/M ratio in the WLM dwarf irregular galaxy *
1
Department of Astronomy, University of Sofia, 5 James Bourchier, Sofia 1164, Bulgaria e-mail: [valcheva;evgeni;japet]@phys.uni-sofia.bg
2
European Southern Observatory, Ave. Alonso de Cordova 3107, Casilla 19, Santiago 19001, Chile e-mail: vivanov@eso.org
Received:
17
November
2005
Accepted:
18
January
2007
We identify the rich carbon star population of the
Magellanic-type dwarf irregular galaxy WLM (Wolf-Lundmark-Melotte)
and study its photometric properties from deep near-IR
observations. The galaxy also exhibits a clear presence of oxygen-rich population. We derive a carbon to M-star ratio of
= 0.56±0.12, relatively high in comparison with many galaxies.
The spatial distribution of the AGB stars in WLM
hints at the presence of two stellar complexes with a size of a
few hundred parsecs.
Using the 
map of WLM and the derived gas-to-dust ratio
for this galaxy N()/E(
) = 60±10 [ 1021 at. cm-2 mag-1] we re-determined the distance modulus of WLM
from the IR photometry of four known Cepheids, obtaining
(
)0 = 24.84±0.14 mag. In addition, we determine the
scale length of 0.75±0.14 kpc of WLM disk in the J-band.
Key words: galaxies: individual: WLM / stars: AGB and post-AGB / stars: carbon / galaxies: irregular / Local Group
© ESO, 2007