Magellanic Clouds; ISM: bubbles; H II regions; stars: winds; outflows; stars: pre-main sequence; X-rays: stars
Abstract :
[en] We report the discovery of extended X-ray emission within the young star cluster NGC 602a in the Wing of the Small Magellanic Cloud (SMC) based on observations obtained with the Chandra X-Ray Observatory. X-ray emission is detected from the cluster core area with the highest stellar density and from a dusty ridge surrounding the H II region. We use a census of massive stars in the cluster to demonstrate that a cluster wind or wind-blown bubble is unlikely to provide a significant contribution to the X-ray emission detected from the central area of the cluster. We therefore suggest that X-ray emission at the cluster core originates from an ensemble of low- and solar-mass pre-main-sequence (PMS) stars, each of which would be too weak in X-rays to be detected individually. We attribute the X-ray emission from the dusty ridge to the embedded tight cluster of the newborn stars known in this area from infrared studies. Assuming that the levels of X-ray activity in young stars in the low-metallicity environment of NGC 602a are comparable to their Galactic counterparts, then the detected spatial distribution, spectral properties, and level of X-ray emission are largely consistent with those expected from low- and solar-mass PMS stars and young stellar objects (YSOs). This is the first discovery of X-ray emission attributable to PMS stars and YSOs in the SMC, which suggests that the accretion and dynamo processes in young, low-mass objects in the SMC resemble those in the Galaxy.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Oskinova, L. M.; Institute for Physics and Astronomy, University Potsdam, D-14476 Potsdam, Germany
Sun, W.; Department of Astronomy, Nanjing University, Nanjing, 210093 Jiangsu, China
Evans, C. J.; UK Astronomy Technology Centre, Royal Observatory Edinburgh, Blackford Hill, Edinburgh EH9 3HJ, UK
Hénault-Brunet, V.; Scottish Universities Physics Alliance (SUPA), Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ, UK
Chu, Y.-H.; Department of Astronomy, University of Illinois, 1002 West Green Street, Urbana, IL 61801, USA
Gallagher, J. S.; Department of Astronomy, University of Wisconsin-Madison, 5534 Sterling, 475 North Charter Street, Madison, WI 53706, USA
Guerrero, M. A.; Instituto de Astrofísica de Andalucía, IAA-CSIC, Glorieta de la Astronomía s/n, E-18008 Granada, Spain
Gruendl, R. A.; Department of Astronomy, University of Illinois, 1002 West Green Street, Urbana, IL 61801, USA
Güdel, M.; Department of Astrophysics, University of Vienna, Türkenschanzstrasse 17, A-1180 Vienna, Austria
Silich, S.; Instituto Nacional de Astrofísica Optica y Electrónica, AP 51, 72000 Puebla, Mexico
Chen, Y.; Department of Astronomy, Nanjing University, Nanjing, 210093 Jiangsu, China
Nazé, Yaël ; Université de Liège - ULiège > GAPHE : Astrophysique observationnelle (sol et espace)
Hainich, R.; Institute for Physics and Astronomy, University Potsdam, D-14476 Potsdam, Germany
Reyes-Iturbide, J.; LATO-DCET/Universidade Estadual de Santa Cruz, Rodovia Jorge Amado, km 16, 45662-000 Ilhéus, BA, Brazil)
