Bibcode
DOI
Gallart, C.; Aparicio, A.; Vilchez, J. M.
Referencia bibliográfica
Astronomical Journal v.112, p.1928
Fecha de publicación:
11
1996
Número de citas
148
Número de citas referidas
133
Descripción
We present deep UBVRI CCD photometry of the resolved stellar content of
the Local Group Dwarf Irregular Galaxy NGC 6822. The main advantage of
this new data is that the color-magnitude (CM) diagrams obtained contain
stars of virtually all ages and metallicities and hence are a record of
the full star formation history of the galaxy. The wide field covered
permits unbiased analysis of the whole galaxy. In turn, the large number
of NGC 6822's measured stars (~18000) ensures that even short-lived
stellar evolutionary phases like AGB will be populated by a significant
number of stars. A derivation from these data of the full star formation
history of the galaxy, using synthetic CM diagrams, will be presented in
two forthcoming papers. In the present paper, we discuss all the
preliminary steps to perform that analysis: we discuss the data, and we
present a detailed study of crowding effects on the photometry using
artificial stars tests. We show the process to obtain all the necessary
information for the simulation of observational effects on the synthetic
CM diagrams to produce model CM diagrams directly comparable with the
observed CM diagrams. In addition, a new estimate of distance and
reddening using Cepheids is presented and compared with the result for
the distance calculated using the tip of the red giant branch as a
distance indicator. A distance modulus of (m-M)_0_ = 23.49+/-0.08 and a
reddening of E(B-V) = 0.24+/-0.03 have been obtained.