INVESTIGADORES
PIATTI Andres Eduardo
congresos y reuniones científicas
Título:
Sobre la naturaleza de cinco candidatos a cúmulos abiertos ubicados próximos a la dirección del centro galáctico
Autor/es:
PIATTI, ANDRÉS E.; CLARIA OLMEDO, JUAN JOSÉ
Lugar:
Buenos Aires
Reunión:
Congreso; Reunión Anual de la Asoc. Argentina de Astronomía; 2002
Resumen:
CCD BVI Johnson-Cousins observations obtained for 1759 stars in
4'×4' regions around the unstudied southern stellar aggregates
Ruprecht 103, 124, 129, 146 and 166 are presented. The objects are
described as open clusters in the catalogues of star clusters and
associations of Alter et al. (1970) and LyngÅ (1987), as well as,
in the ESO/Uppsala Survey of the ESO (B) Atlas (Lauberts 1982). Our
analysis shows that none of these objects are genuine open clusters,
except perhaps Ruprecht 166, since no clear main sequences (MSs) or
other meaningful features can be seen in the extracted (V,B-V) and
(V,V-I) colour-magnitude diagrams (CMDs). The star sequences seen in the
distinct CMDs, specially for Ruprecht 124 and 129, are apparently formed
by the superimposition of MS field stars affected by varying amounts of
interstellar absorption and/or placed at different distances from the
Sun. The CMDs of Ruprecht 166 present a pronounced variation in the
luminosity function along the apparent MS, a fact from which we can
infer the notion of these stars had a different origin. Star counts
carried out within and outside the cluster candidate fields not only
support the results that the objects do not present a significant number
density contrast with respect to the Galactic disk, but also show that
they do not appear to be candidate late stages of star cluster dynamical
evolution. Several other stellar aggregates included in open cluster
catalogues have previously been disproved as genuine physical systems
(see, e.g., Carraro & Patat 1995, MNRAS, 276, 563; Carraro 2000,
A&A, 357, 145; Piatti & Clariá 2001, A&A, 370, 931).
Thus, the present work implies the potential likelihood of other wrongly
classified open clusters.