Fotometría CCD de NGC 6994: ?` Un cúmulo abierto disperso?

Bassino, L. P.; Waldhausen, S.; Martínez, R. E.
Referencia bibliográfica

Boletín de la Asociación Argentina de Astronomía, vol.41, p.75-76

Fecha de publicación:
0
1997
Número de autores
3
Número de autores del IAC
0
Número de citas
0
Número de citas referidas
0
Descripción
We present the preliminary results of BV(RI)KC CCD photometry down to V = 21 mag. in the region of NGC 6994. To our knowledge, no photometry has been previously reported for this object and we suggest it to be a poor and sparse old open cluster. The colour excess is estimated at EB-V = 0.10 ± 0.02 mag. by means of the BVIC technique and the distance at approximately 500 pc. (V0-MV = 8.5 ± 0.25 mag). As the galactic latitude is b = -34o, this puts NGC 6994 at about 280 pc. below the galactic plane. The theoretical isochrones (VandenBerg, 1985) that are in better agreement with the data correspond to a range in age of 2.5 - 4 Gyr., assuming solar metallicity. According to this results, NGC 6994 probably belongs to the old open cluster population (ages of 1 Gyr. or greater) that are located in the outer disk and at large distances from the galactic plane (Janes y Phelps, 1994).