IALP   13078
INSTITUTO DE ASTROFISICA LA PLATA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Refining the true parameters of the open cluster NGC 4852
Autor/es:
GLADYS SOLIVELLA, EDGARD GIORGI, RUBÉN VÁZQUEZ AND GIOVANNI CARRARO
Lugar:
Rio de Janeiro-Brasil
Reunión:
Congreso; XXVII General Assembly IAU; 2009
Institución organizadora:
International Astronomical Union
Resumen:
NGC 4852 is a moderately compact cluster centered at α2000 =
13 : 00 : 09; δ = −59 : 36 : 48, located near the center of an Hα
superring. This cluster forms part of an extended region including young
stellar aggregates inside a circle with a radius of 3 degrees, where
many show an abundance of emission line stars. In the field of this
cluster, two stars of known type exist: Wray 151039 (emission-line
object) and CD −58:4845 (emission-line star). We do not yet know whether
the Be phase is transient or whether it is just what randomly happens
in some hot stars. It appears that Be star may be found even in clusters
as old as 70 Myr with a high occurrence rate in clusters of 2527 Myr
old. A recent photometric survey in NGC 4852 down to V = 22 23 mag established that NGC 4852 is about 200 250 Myr old, located at 1.1 kpc from the Sun and with a mean E(B − V)
= 0.45 mag. Since the presence of potential Be-type stars in the
cluster area suggests it may be a very young object instead of
moderately old, we decided to carry out spectroscopy for 33 selected
stars and CCD UBVI photometry for the bright objects in the
cluster area. This way, we attempt to clarify their evolutionary state
and include them in the framework of emission-line stars and open
clusters. From our analysis, we agree with the cluster distance and
reddening determined by earlier studies, but we derive that the age of
NGC 4852 is younger than 40 Myr.