Discovery of X-ray emission from young suns in the Small Magellanic Cloud. (arXiv:1301.3500v1 [astro-ph.SR])

Discovery of X-ray emission from young suns in the Small Magellanic Cloud. (arXiv:1301.3500v1 [astro-ph.SR]):
We report the discovery of extended X-ray emission within the young star
cluster NGC 602 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 HII 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 new-born 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.