University of Hertfordshire

From the same journal

From the same journal

By the same authors

Confirmation of a New Metal-poor Globular Cluster in the Galactic Bulge

Research output: Contribution to journalArticle

View graph of relations
Original languageEnglish
Article number12
Number of pages19
JournalThe Astrophysical Journal
Journal publication date5 Oct 2018
Volume866
Issue1
DOIs
StatePublished - 5 Oct 2018

Abstract

We use deep near-IR photometry of the VISTA Variables in the Via Lactea (VVV) Survey and deep DECam Plane Survey (DECaPS) optical photometry to confirm the physical reality of the candidate globular cluster (GC) Minni 22, located in the Galactic bulge. This object, detected as a high density region in our maps of bulge red giants, is now confirmed as a real GC based on the optical and near- IR color-magnitude diagrams. We also recover 3 known fundamental mode (ab type) RR Lyrae stars within 2 arcmin of the cluster center. The presence of RR Lyrae stars seems also to confirm Minni 22 as a bonafide old and metal-poor globular cluster. We estimate a cluster reddening E(J − Ks) = 0.6 mag, and determine its heliocentric distance D = 7.4 ± 0.3 kpc. The optical and near-IR color- magnitude diagrams reveal well-defined red giant branches in all cases, including a red giant branch bump at Ks = 13.30±0.05 mag. The comparison with theoretical isochrones yields a mean metallicity of [Fe/H] = −1.3±0.3 dex, and age of t ∼ 11.2 Gyr. This is a good example of a new low luminosity (MV = −6.2 mag) GC found in the central bulge of the Milky Way. After discussing the different ways to confirm the existence of bulge GC candidates, we find that one of the best methods is to use the CMDs from the combination of the DECaPS + VVV photometries.

Notes

© 2018. The American Astronomical Society. All rights reserved.

ID: 15573572