Astron. Astrophys. Suppl. Ser. 142, 347-352
The stellar content and distance to the
nearby blue compact dwarf galaxy NGC 6789
I. Drozdovsky 1 - N. Tikhonov 2
Send offprint request: I. Drozdovsky;
1 - Astronomical Institute, St.-Petersburg State
University, Petrodvoretz 198904, Russia
2 - Special Astrophysical Observatory, N.Arkhyz, Karachai-Circassian Rep.
Received August 21, 1998; accepted October 19, 1999
In this paper we present the results of a detailed B
, and H
study of the isolated nearby blue compact dwarf (BCD) galaxy NGC 6789.
The observed galaxy has not yet been resolved
into stars up to now. On CCD frames obtained with 6 m BTA telescope and
2.5 m Nordic telescope the galaxy is well resolved.
Its colour-magnitude diagram confirms the two component
(core-halo) galaxy morphology, which consists of two stellar populations
distinct in structure and colour: an inner high surface-brightness
young population within 150 pc from the center of the galaxy,
and a relatively low surface-brightness intermediate-age population
extending out to at least 600 pc.
The distance to the galaxy, estimated from the
tip of the red giant branch (TRGB) is 2.1 Mpc which places
NGC 6789 close to the Local Group. From the mean colour of the RGB,
the mean metal abundance of the halo population is estimated as
Key words: nearby galaxies: dwarf galaxies (NGC 6789): distance moduli: star content
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