Volume 418, Number 3, May II 2004
|Page(s)||979 - 988|
|Section||Galactic structure, stellar clusters, and populations|
|Published online||16 April 2004|
The relatively young, metal-poor and distant open cluster NGC 2324
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: email@example.com;firstname.lastname@example.org
Corresponding author: A. E. Piatti, email@example.com
Accepted: 21 January 2004
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 colours for 2865 stars and T1 magnitudes and colours for 1815 stars in an area of 136 136. The comparison of the cluster colour–magnitude diagrams with isochrones of the Geneva group yield = 0.33 ± 0.07 and = 13.70 ± 0.15 for log t = 8.65 (t = 440 Myr) and Z = 0.008 ([Fe/H] = -0.40), and = 0.40 ± 0.10 and = 13.65 ± 0.15 for the same age and metallicity level. The resulting reddening value implies = 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 53 ± 03 (5.9 pc). When using the reddening value here derived and the original Washington photometric data of [CITE] 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
© ESO, 2004
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