Globular cluster candidates in the Sagittarius dwarf galaxy

A.E. PIATTI

ASTRONOMICAL JOURNAL

IOP PUBLISHING LTD

Lugar: Londres; Año: 2021 vol. 162 p. 1 - 10

0004-6256

Recently,  new Sagittarius (Sgr) dwarf galaxy globular clusters werediscovered, which opens the question on the actual size of the Sgr globular clusterpopulation, and therefore on our understanding of the Sgr galaxy formation andaccretion history onto the Milky Way. Based on {it Gaia} EDR3 and SDSS IV DR16(APOGEE-2) data sets, we performed an analysis of the color-magnitudediagrams (CMDs) of the eight new Sgr globular clusters  found by citet{minnitietal2021}from a sound cleaning of the contamination of Milky Way and Sgr field stars, complemented by available kinematic and metal abundance information. The cleaned CMDs andspatial stellar distibutions reveal thepresence of stars with a wide range of cluster membership probabilities. Minni~332 turned out to be a younger ($<$ 9 Gyr) and more metal-rich ([M/H] $ga$ -1.0dex) globular cluster than M54, the nuclear Sgr globular cluster, as could also bethe case of Minni~342, 348, and 349, although their results are less convincing.Minni~341 could be an open cluster candidate (age $<$ 1 Gyr, [M/H] $sim$-0.3 dex), while the analyses of Minni~335, 343, and 344 did not allow us to confirmtheir physical reality. We also built the Sgr cluster frequency (CF) using availableages of the Sgr globular clusters and compared it with that obtained from the Sgr star formationhistory. Both CFs are in excellent agreement. However, the addition of eight newglobular clusters with ages and metallicities distributed according to the Sgr age-metallicity relationship turns out in a remarkably different CF.