`First estimates of the fundamental parameters of the relatively bright Galactic open cluster NGC\,5288 relatively bright Galactic open cluster NGC 5288

A.E. PIATTI, J.J. CLARIÁ, A.V. AHUMADA

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

Royal Astronomical Society

Lugar: London; Año: 2006 vol. 367 p. 599 - 610

0035-8711

In this paper we present CCD images in the Johnson $B$ and $V$ and Kron-Cousins $I$ passbands which have been obtained for the previously unstudied open cluster NGC,5288. The sample consists of 15688 stars reaching down to $V$ $sim$ 20.5. The cluster appears to have a relatively small but conspicuous nucleus and a low-density extended coronal region. Star counts carried out in 25-pixel a side boxes distributed throughout the whole observed field allowed us to estimate the angular core and corona radii as $sim$ 1.3$arcmin$ and 6.3$arcmin$, respectively. Our analysis suggests that NGC,5288 is moderately young and probably more metal-rich than the Sun. Adopting the theoretical metal content $Z$ = 0.040, which provides the best global fit, we derive an age of ({f 130} $^{ m +40}_{ m -30}$) Myr. Simultaneously, we have obtained colour excesses $E(B-V)$ = 0.75 and $E(V-I)$ = 0.95 and an apparent distance modulus $V-M_{V}$ = 14.00. The law of interstellar extinction in the cluster direction is found to be normal. NGC,5288 is located at (2.1 $pm$ 0.3) kpc from the Sun beyond the Carina spiral feature and $sim$ 7.4 kpc from the Galactic centre. The cluster metallicity seems to be compatible with the cluster position in the Galaxy, given the recognized radial abundance gradient in the disk. For the first time, we determine in this paper the basic parameters for the open cluster NGC,5381, situated in the same direction as NGC,5288. This determination was reached by using CCD $VI$ data published by Pietrzy´nski et al.shortcite{petal97} for NGC,5381. The properties of some open clusters aligned along the line-of-sight of NGC,5288 are examined. The properties of clusters of similar ages to NGC,5288 are also looked into. Evidence is presented that these ones did not form mainly along the spiral arms but rather in the thin Galactic disk ($Z$ $sim$ $pm$ 100 pc).