Globular cluster candidates in the Sagittarius dwarf galaxy. (arXiv:2109.06731v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Piatti_A/0/1/0/all/0/1">Andrés E. Piatti</a>
Recently, new Sagittarius (Sgr) dwarf galaxy globular clusters were
discovered, which opens the question on the actual size of the Sgr globular
cluster population, and therefore on our understanding of the Sgr galaxy
formation and accretion history onto the Milky Way. Based on Gaia EDR3 and SDSS
IV DR16 (APOGEE-2) data sets, we performed an analysis of the color-magnitude
diagrams (CMDs) of the eight new Sgr globular clusters found by from a sound
cleaning of the contamination of Milky Way and Sgr field stars, complemented by
Minniti et al. (2021b) available kinematic and metal abundance information. The
cleaned CMDs and spatial stellar distributions reveal the presence 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] > -1.0 dex) globular cluster
than M54, the nuclear Sgr globular cluster, as could also be the 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] ~ -0.3 dex), while the
analyses of Minni 335, 343, and 344 did not allow us to confirm their physical
reality. We also built the Sgr cluster frequency (CF) using available ages of
the Sgr globular clusters and compared it with that obtained from the Sgr star
formation history. Both CFs are in excellent agreement. However, the addition
of eight new globular clusters with ages and metallicities distributed
according to the Sgr age-metallicity relationship turns out in a remarkably
different CF.
Recently, new Sagittarius (Sgr) dwarf galaxy globular clusters were
discovered, which opens the question on the actual size of the Sgr globular
cluster population, and therefore on our understanding of the Sgr galaxy
formation and accretion history onto the Milky Way. Based on Gaia EDR3 and SDSS
IV DR16 (APOGEE-2) data sets, we performed an analysis of the color-magnitude
diagrams (CMDs) of the eight new Sgr globular clusters found by from a sound
cleaning of the contamination of Milky Way and Sgr field stars, complemented by
Minniti et al. (2021b) available kinematic and metal abundance information. The
cleaned CMDs and spatial stellar distributions reveal the presence 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] > -1.0 dex) globular cluster
than M54, the nuclear Sgr globular cluster, as could also be the 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] ~ -0.3 dex), while the
analyses of Minni 335, 343, and 344 did not allow us to confirm their physical
reality. We also built the Sgr cluster frequency (CF) using available ages of
the Sgr globular clusters and compared it with that obtained from the Sgr star
formation history. Both CFs are in excellent agreement. However, the addition
of eight new globular clusters with ages and metallicities distributed
according to the Sgr age-metallicity relationship turns out in a remarkably
different CF.
http://arxiv.org/icons/sfx.gif
