Small Magellanic Cloud field stars meddling in star cluster age estimates

ANDRÉS E. PIATTI

Research Notes of the AAS

AAS IOP

Año: 2022 vol. 6 p. 271 - 271

I revisited the age of the Small Magellanic Cloud cluster HW~42, whose previous estimates differ in more than 6 Gyr, thus challenging the most updated knowledge of the SMC star formation history. I performed an analysis of number stellar density profiles atdifferent brightness levels; carried out a field star decontamination of thecluster color-magnitude diagram; and estimated the cluster fundamental parameters fromthe minimization of likelihood functions and their uncertainties from standard bootstrap methods. I conclude that HW~42 is a 6.2$^{m +1.6}_{m -1.3}$ Gyr old ([Fe/H] = -0.89$^{m +0.10}_{m -0.11}$ dex) SMC clusterprojected on to a SMC composite star field population which shows variations in magnitude, color, and stellar density of Main Sequence stars. The present outcome solves theconundrum of the previous age discrepancies and moves HW~42 to a region in theSMC age-metallicity relationship populated by star clusters.