New Milky Way Bulge Globular Clusters From The VVVX Survey: Open Questions
Abstract
The VISTA Variables in the Via Lactea Extended Survey (VVVX) is a public near-IR survey of our Galaxy, continuation of the VVV Survey (http://vvvsurvey.org). We present our latest results on the globular cluster (GC) system of the Milky Way (MW) bulge. In particular, the deep VVVX near-IR images have allowed the discovery of new GC candidates in the inner MW, previously hidden by heavy extinction and crowding. The deep near-IR PSF photometry and multi-epoch observations also produced millions of variable stars and accurate proper motions. We use RR Lyrae and red clump giants to measure the physical parameters for dozens of new GCs (sizes, extinctions, distances, ages, luminosities, etc.). The VVVX observations of the innermost GCs contribute to characterize the formation and evolution of the MW bulge. The confirmation of new GCs in the bulge is very difficult, and we present a few specific examples. The candidate GC VVV-CL04 was originally discarded, but we confirm this as a real GC. Also, Minni 35 was a discarded candidate GC, but we confirm that this is a young open cluster in the Galactic center region. The VVV survey detected a very reddened GC in the MW plane, VVV-GC003, located beyond the bulge at 13.5 kpc. We also investigate the GCs in the central region of the MW that are severely crowded and obscured, finding that VVV-CL002 is the closest GC to the Galactic Center, with R=0.7 kpc. Finally, we discovered a dozen GCs in the Sagittarius dwarf galaxy, which is located behind the MW bulge.
- Publication:
-
Boletin de la Asociacion Argentina de Astronomia La Plata Argentina
- Pub Date:
- July 2021
- Bibcode:
- 2021BAAA...62..107M
- Keywords:
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- galaxies: individual (Milky Way);
- Galaxy: structure;
- globular clusters: general;
- stars: evolution