The age-metallicity relationship in the Small Magellanic Cloud periphery

A.E. PIATTI

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2015 vol. 451 p. 3219 - 3227

0035-8711

We present results from Washington CT1 photometry for eleven star fields locatedin the western outskirts of the Small Magellanic Cloud (SMC), which cover angulardistances to its centre from 2 up to 13 degrees (≈ 2.2 − 13.8 kpc). The colour-magnitude diagrams, cleaned from the unavoidable Milky Way (MW) and backgroundgalaxy signatures, reveal that the most distant dominant main sequence (MS) stellarpopulations from the SMC centre are located at an angular distance of ∼ 5.7 deg(6.1 kpc); no sign of farther clear SMC MS is visible other than the residuals fromthe MW/background field contamination. The derived ages and metallicities for thedominant stellar populations of the western SMC periphery show a constant metallicitylevel ([Fe/H] = -1.0 dex) and an approximately constant age value (≈ 7−8 Gyr). Theirage-metallicity relationship (AMR) do not clearly differ from the most comprehensiveAMRs derived for almost the entire SMC main body. Finally, the range of ages of thedominant stellar populations in the western SMC periphery confirms that the majorstellar mass formation activity at the very early galaxy epoch peaked ∼ 7-8 Gyr ago.