Issue |
A&A
Volume 429, Number 3, January III 2005
|
|
---|---|---|
Page(s) | 837 - 850 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361:20041608 | |
Published online | 05 January 2005 |
Near-IR observations of NGC 6822: AGB stars, distance, metallicity and structure*
1
European Southern Observatory, Karl–Schwarzschild–Straße 2, 85748 Garching bei München, Germany e-mail: mcioni@eso.org
2
Sterrewacht Leiden, Niels Bohrweg 2, 2333 RA Leiden, The Netherlands
Received:
7
July
2004
Accepted:
3
September
2004
Observations in the IJKs wave bands covering the
central of the Local Group galaxy NGC 6822 have been made with the William Herschel Telescope in La
Palma. They have allowed us to characterize, for the first time in
the near-infrared across the whole galaxy, its late-type stellar
population (i.e. red giant and asymptotic giant branch stars) and to
derive from the ratio between carbon-rich and oxygen-rich asymptotic
giant branch stars an indication about spatial variations in
metallicity. These amount to about 1.56 dex, twice of what has been
previously found within each Magellanic Cloud using the same
technique. We have calibrated our photometry on the DENIS (I-band)
and 2MASS (J and Ks bands) data and obtained a distance
modulus of
from the position of the tip of the
RGB. The large scale distribution of late-type stars suggests that
either the galaxy is viewed under a high inclination angle or it has a
non-negligible thickness.
Key words: stars: late-type / stars: distances / galaxies: Local Group / galaxies: abundances / galaxies: photometry / infrared: stars
© ESO, 2005
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