BibSonomy
CiteUlike
Connotea
Del.icio.us
Digg
Facebook
A&A 418, 979-988 (2004)
DOI: 10.1051/0004-6361:20041015
The relatively young, metal-poor and distant open cluster NGC 2324
A. E. Piatti1, J. J. Clariá2 and A. V. Ahumada21 Instituto de Astronomía y Física del Espacio, CC 67, Suc. 28, 1428 Buenos Aires, Argentina
2 Observatorio Astronómico, Universidad Nacional de Córdoba, Laprida 854, 5000 Córdoba, Argentina
e-mail: claria@mail.oac.uncor.edu;andrea@mail.oac.uncor.edu
(Received 12 January 2004 / Accepted 21 January 2004 )
Abstract
We have obtained CCD photometry in the Johnson
V, Kron-Cousins
I and
CT1 Washington systems for NGC 2324, a rich open cluster located ~35
from the Galactic anticentre direction. We measured
V magnitudes
and
V-I colours for 2865 stars and
T1 magnitudes and
C-T1 colours
for 1815 stars in an area of 13
6
13
6. The comparison
of the cluster colour-magnitude diagrams with isochrones of the Geneva group
yield
E(V-I) = 0.33
0.07 and
V-MV = 13.70
0.15 for log
t =
8.65 (
t = 440 Myr) and
Z = 0.008 ([Fe/H] = -0.40), and
E(C-T1) = 0.40
0.10 and
T1-MT1 = 13.65
0.15 for the same age and
metallicity level. The resulting
E(V-I) reddening value implies
E(B-V) =
0.25
0.05 and a distance from the Sun of (3.8
0.5) kpc. Star counts
carried out within and outside the cluster region allowed us to estimate the
cluster angular radius as 5
3
0
3 (5.9 pc). When using
the
E(B-V) reddening value here derived and the original Washington
photometric data of Geisler et al. (1991) for the stars confirmed
as red cluster giants from Coravel radial velocities, we found [Fe/H] = -0.31
0.04, which is in good agreement with the best fits of isochrones.
Therefore, NGC 2324 is found to be a relatively young, metal-poor and distant
open cluster located beyond the Perseus spiral arm. A comparison of NGC 2324
with 10 well-known open clusters of nearly the same age shows that
the cluster metal abundance and its position in the Galaxy are consistent
with the existence of a radial abundance gradient of -0.07 dex kpc
-1 in
the Galactic disc.
Key words: Galaxy: open clusters and associations: individual: NGC 2324 -- Galaxy: general -- techniques: photometric
Offprint request: A. E. Piatti, andres@iafe.uba.ar
SIMBAD Objects
Tables at the CDS
© ESO 2004