Fotometría multicolor y observaciones Coravel de estrellas en el cúmulo abierto IC 2488

CLARIA OLMEDO, JUAN JOSÉ; PIATTI, ANDRÉS E.; LAPASSET, EMILIO; MERMILLIOD, J.C.

La Plata

Congreso; Reunión Anual de la Asoc. Argentina de Astronomía; 2003

We present new UBV photometry of 119 stars in the open cluster IC 2488, supplemented by DDO and Washington photometry and Coravel radial velocities for a sample of red giant candidates. Nearly 50% of the stars sampled - including three red giants and one blue straggler - are found to be cluster members. Photometric membership probabilities of the red giant candidates show good agreement with those obtained from Coravel data. A mean radial velocity of (-2.63 ± 0.06) km/seg is derived for the cluster giants, while the mean colour excess is E(B-V) = 0.24 ± 0.04. IC 2488, located at a distance of (1250 ± 120) pc from the Sun, is most probably not related to the planetary nebula ESO 166-PN21. A metal abundance [Fe/H] = 0.10 ± 0.06 relative to the Sun is determined from DDO data of the red giant members, in good agreement with the [Fe/H] values derived from the Washington photometric data. By using this metallicity and the theoretical isochrones computed with core overshooting for the Washington system, an age of 180 Myr is determined. The isochrone corresponding to this age reproduces remarkably well not only the morphology of the upper main sequence but also the observed red giant pattern (Clariá et al. 2003, A&A, 399, 543).