High quality seeing V, I and Gunn Z imaging of Terzan 4: a blue horizontal branch bulge globular cluster.
Abstract
We study the globular cluster Terzan 4 projected close to the Galactic center, by means of V, I and Gunn z Colour-Magnitude Diagrams. The images were obtained under exceptional seeing conditions (0.35"-0.55") at the ESO New Technology Telescope equipped with SUSI. We derive a reddening of E(B-V)=2.35 and a distance from the Sun dsun_=8.3kpc for Terzan 4. From the similarity of the VI Colour-Magnitude Diagrams of Terzan 4 and M30, in particular the presence of a blue horizontal branch, it could be as metal-poor as [Fe/H]=~-2.0. It is therefore another blue horizontal branch globular cluster located close to the Galactic center.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- March 1997
- Bibcode:
- 1997A&A...319..850O
- Keywords:
-
- GLOBULAR CLUSTERS: INDIVIDUAL: TERZAN 4;
- M 30;
- GENERAL;
- HR DIAGRAM;
- GALAXY: CENTER