| Issue |
Astron. Astrophys. Suppl. Ser.
Volume 136, Number 3, May I 1999
|
|
|---|---|---|
| Page(s) | 461 - 470 | |
| DOI | https://doi.org/10.1051/aas:1999228 | |
| Published online | 15 May 1999 | |
Deep multicolor CCD photometry of the globular cluster NGC 6723 *
1
Isaac Newton Institute, Ministry of Education of Chile, Casilla 8-9, Correo 9, Santiago, Chile
2
Sternberg Astronomical Institute and Isaac Newton Institute Moscow Branch, 13 University Ave., Moscow 119899, Russia
3
Institute of Astronomy of Russian Acad. Sci. and Isaac Newton Institute Moscow Branch, 48 Pyatnitskaya Str., Moscow 109017, Russia
Send offprint request to: G. Alcaíno
Received:
17
November
1998
Accepted:
23
March
1999
We have obtained CCD UBVRI photometry of 3620 stars in the globular cluster
NGC 6723, one of the few globular clusters with a horizontal branch
well-populated on both sides of the instability strip. This is the first
deep five-color study of NGC 6723. We have determined
several important parameters for this cluster. Its color excess is
. The most plausible value of metallicity is
;
even lower values are possible. The apparent distance modulus of the
cluster is 
. From isochrone analysis,
we prefer the NGC 6723 age in the range between 15 and 16 Gyr,
in the scale of Bergbusch & VandenBerg (1992). We find a close similarity
of the shape and slope of the red giant branch in NGC 6723 and
M 3 and of the magnitude difference between the main-sequence
turnoff and the horizontal branch in NGC 6723, M 3, and M 5.
Key words: globular clusters: individual (NGC 6723)
© European Southern Observatory (ESO), 1999