Evolving Stars?
To test whether different evolutionary stages are present in the cluster, we looked at
the spatial distribution of these two possible populations. From this it appears that
the “red,” highly embedded, and probably
younger, YSOs are mainly distributed around
the northwest region (top right), while the
“blue,” and probably older, population is
preferentially located toward the southeast
(bottom left) region. This distribution seems
to indicate the presence of an age gradient
diagonally across the image, and where the
denser cluster region would be younger
than the blue sub-cluster region.
We also found that one of the bluest massive
stars, located in the southeast sub-cluster, is
likely the ionizing source of the region. This
star probably is the one that originally lit up RCW 41, and has already cleaned up its environment.
On the other hand, moving toward
the dense cluster region, the presence of a dense clump of molecular gas has been detected, a signpost of active ongoing high-mass
star formation. This suggests that
star formation progresses toward
the clump and could have been
triggered by the interaction of the
ionized region with the clump.
should be a fair representation of the underlying Initial Mass Function (IMF).
The IMF is a fundamental parameter to
characterize cluster properties, and various
theories of star formation predict different
outcomes for its overall shape. However, as
for the age, deriving a mass for each star is
an indirect process, and many uncertainties
may add up along the way.
We derived the IMF of the young cluster,
which is presented in Figure 5. Among the
first interesting features is that we can detect and study stars down to a mass limit
of ~ 0.01 solar mass — only 10 times the
mass of Jupiter! Only the gain in sensitivity
brought by GeMS/GSAOI allows us to reach
such a low mass limit in a cluster as distant
as RCW 41.
Figure 5.
Mass distribution of the
young cluster forming
at the edge of the RCW
41 HII region. Thanks to
the gain in resolution
and sensitivity brought
by GeMS/GSAOI, masses
down to 0.01 solar mass
are probed in this cluster.
Cluster Mass
Distribution
To go one step further, we derived
the mass and mass distribution of
the dense cluster, formed at the
edge of the RCW 41 HII region. The
stars in this region have roughly
the same age and metallicity. In
addition, since the effects of stellar and dynamical evolution are
minimal in young clusters, the observed present day mass function
January 2016
2015 Year in Review
GeminiFocus
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