Revisiting a detached stellar structure in the outer northeastern region of the Small Magellanic Cloud

PIATTI, ANDRÉS; E.

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2022 vol. 509 p. 3462 - 3469

0035-8711

The outer northeastern region of the Small Magellanic Cloud (SMC) is populated bya shell-like overdensity whose nature was recently investigated. We analyzed twentycatalogued star clusters projected onto it from Survey of the MAgellanic Stellar His-tory data sets. After carrying out a cleaning of field stars in the star cluster colour-magnitude diagrams (CMDs), and deriving their astrophysical properties from thecomparison between the observed and synthetic CMDs, we found that four objectsare not genuine star clusters, while the remaining ones are young star clusters (11, age∼ 30-200 Myr) and intermediate-age (5, age ∼ 1.7-2.8 Gyr) star clusters, respectively.The resulting distances show that intermediate-age and some young star clusters be-long to the SMC main body, while the remaining young star clusters are nearly 13.0kpc far away from those in the SMC, revealing that the shell-like overdensity is moreextended along the line-of-sight than previously thought. We also found a clear agetrend and a blurred metallicity correlation along the line-of-sight of young clusters,in the sense that the farther a star cluster from the SMC, the younger, the moremetal rich, and the less massive it is. These young clusters are also affected by aslightly larger interstellar reddening than the older ones in the shell-like overdensity.These outcomes suggest that the shell-like overdensity can possibly be another tidallyperturbed/formed SMC stellar structure from gas striped off its body, caused by theinteraction with the Large Magellanic Cloud or the Milky Way.