| Issue |
Astron. Astrophys. Suppl. Ser.
Volume 138, Number 2, August 1999
|
|
|---|---|---|
| Page(s) | 267 - 273 | |
| DOI | https://doi.org/10.1051/aas:1999275 | |
| Published online | 15 August 1999 | |
Blue horizontal branch globular clusters towards the bulge: Terzan 9, NGC 6139 and NGC 6453 *
1
Università di Padova, Dept. di Astronomia, Vicolo dell'Osservatorio 5, I-35122 Padova, Italy and European Southern Observatory, Karl Schwarzschild Strasse 2, D-85749 Garching bei München, Germany
2
Universidade Federal do Rio Grande do Sul, Dept. de Astronomia, CP 15051, Porto Alegre 91500-970, Brazil
3
Universidade de São Paulo, CP 3386, São Paulo 01060-970, Brazil
Send offprint request to: B. Barbuy
Received:
10
May
1999
Accepted:
7
June
1999
We present V and I photometry of the globular clusters Terzan 9 and NGC
6453 for the first time, and also of NGC 6139.
The three clusters are projected towards the bulge. The Colour-Magnitude
Diagram morphologies reveal that the sample clusters have blue horizontal
branches. This characterizes an important fraction of the clusters projected
on the bulge, with implications on the early Galaxy history.
From the colour-magnitude diagrams we derive reddenings of 
and distances 
, 9.4, 8.5 kpc respectively
for Terzan 9, NGC 6139 and NGC 6453. We conclude that these metal-poor
clusters are within the bulge volume.
Key words: globular clusters: Terzan 9, NGC 6139, NGC 6453 / HR diagram / stars: horizontal branch
© European Southern Observatory (ESO), 1999