Triggered star formation in the inner wing of the SMC. Two possible supernova explosions in the N83-84-85 region^*

¹ École Nationale Supérieure des Télécommunications, Département Traitement du Signal et des Images, 46 rue Barrault, 75013 Paris, France e-mail: bratsoli@tsi.enst.fr
² Department of Astrophysics, Astronomy and Mechanics, Faculty of Physics, University of Athens, 15783 Athens, Greece
³ National Observatory of Athens, Institute of Astronomy and Astrophysics, Lofos Koufou - P. Penteli, 15236 Athens, Greece

Received: 1 December 2003
Accepted: 3 May 2004

Abstract

In this article we study the N83-84-85 region of the inner wing of the SMC. Direct and low-dispersion objective prism plates taken with the 1.2 m UK Schmidt Telescope have been digitized by the SuperCOSMOS machine. Star counts have been performed for our region in selected luminosity slices in the U filter and isodensity contours have been used to identify the structures with enhanced stellar number density. We find evidence of triggered star formation from massive stars of older to more recent OB associations. Circular arcs constructed by O and B stars have been detected. A study of the population places stars with more recent ages in the groups of the arcs than of their centers. These effects can be explained by supernova explosions. A catalogue of the non-saturated detected OB stars in this region is given.