INVESTIGADORES
PIATTI Andres Eduardo
artículos
Título:
Membership, binarity and metallicity of red giants in the southern open cluster NGC 2354
Autor/es:
CLARIA OLMEDO, JUAN JOSÉ; MERMILLIOD, J.C.; PIATTI, ANDRÉS E.
Revista:
ASTRONOMY & ASTROPHYSICS. SUPPLEMENT SERIES (PRINT)
Referencias:
Año: 1999 vol. 134 p. 301 - 308
ISSN:
0365-0138
Resumen:
We present new Coravel radial-velocity observations and photoelectric
photometry in the UBV, DDO and Washington systems for a sample of red
giant candidates in the field of the intermediate-age open cluster NGC
2354. Photometric membership probabilities show very good agreement with
those obtained from Coravel radial velocities. The analysis of the
photometric and kinematical data allow us to confirm cluster membership
for 9 red giants, one of them being a spectroscopic binary, while 4
confirmed spectroscopic binaries appear to be probable members. We have
also discovered 4 spectroscopic binaries not belonging to the cluster. A
mean radial velocity of (33.40 +/- 0.27) km s(-1) and a mean reddening
E(B-V) = 0.13 +/- 0.03 were derived for the cluster giants. NGC 2354 has
a mean ultraviolet excess <delta (U-B)> = -0.03 +/- 0.01, relative
to the field K giants, and a mean new cyanogen anomaly Delta CN = -0.035
+/- 0.007, both implying [Fe/H] ~ -0.3. The moderately metal-poor
character of NGC 2354 is confirmed using five different metal abundance
indicators of the Washington system. The cluster giant branch is formed
by a well defined clump of 7 stars and 4 stars with high membership
probabilities seem to define an ascending giant branch. The whole red
giant locus cannot be reproduced by any theoretical track.