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André E. Piatti

Publications and source records attributed to André E. Piatti.

2 recordsLinked to original sources

APOGEE physical properties of globular cluster tidal tails

A recent model prediction claimed that exists a correlation between the formation scenarios of globular clusters, i.e., whether they formed in situ, or in dark matter halos that were accreted into the Milky way, with some properties of their tidal tails, particularly, their widths ($w$), their dispersion in the z-component of the angular momentum ($σ$$_{\rm L_z}$ ), and in the line-of-sight ($σ$$_{\rm V_{LOS}}$) and tangential ($σ$$_{\rm V_{Tan}}$) velocities. I exploited the APOGEE DR17 data base and selected highly confident tidal tails members of 17 Milky Way globular clusters, for which the above four properties were computed for the first time. From all possible paired property combinations, I found that $σ$$_{\rm V_{LOS}}$ and $σ$$_{\rm V_{Tan}}$ resulted to be highly correlated, nearly to the identity relationship. This observation-based correlation resulted to be in an overall very good agreement with that arising from the aforementioned predictions. Additionally, when the four analyzed properties are linked to the accretion groups of the Milky way to which the globular clusters are meant to be associated, I found kinematically cold and hot tidal tails pertaining to globular clusters distributed in all the considered accretion groups. This outcome could be an evidence that globular clusters form in galaxies within a wide variety of dark matter halos, with different masses and profiles.

astro-ph.GA↗

The VMC Survey - XII. Star cluster candidates in the Large Magellanic Cloud

In this work we analyse Colour-Magnitude Diagrams (CMDs) of catalogued star clusters located in the Large Magellanic Cloud (LMC), from a YJKs photometric data set obtained by the Visible and Infrared Survey Telescope for Astronomy (VISTA) survey of the Magellanic Clouds system (VMC). We studied a total of 98 objects of small angular size, typically ~ 11.6 pc in diameter projected towards both uncrowded tile LMC 8_8 and crowded tile LMC 5_5. They populate relatively crowded LMC fields with significant fluctuations in the stellar density, the luminosity function, and the colour distribution as well as uncrowded fields. This cluster sample is aimed at actually probing our performance in reaching the CMD features of clusters with different ages in crowded/uncrowded fields. We applied a subtraction procedure to statistically clean the cluster CMDs from field star contamination. We then matched theoretical isochrones to the background-subtracted CMDs to determine the ages and metallicities of the clusters. We estimated the ages of 65 clusters, which resulted to be in the age range 7.3 < log(t/yr) < 9.55. We also classified as chance grouping of stars 19 previoulsy catalogued clusters, two possible cluster-like asterisms, and one unresolved cluster. For other 8 objects, we could not find a clear star concentration in the Ks images either, so we quoted them as cluster-like asterisms. Finally, we found two previously catalogued single star clusters to be unresolved background galaxies (KMHK747, OGLE366), and one to be a triple cluster system (BSDL 2144).

astro-ph.GA↗