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The Rosette Nebula (also
known as Caldwell 49) is a
large, circular H
II region located near one end of a giant molecular
cloud in the Monoceros region
of the Milky
Way Galaxy. The open
cluster NGC
2244 (Caldwell 50) is closely associated with the
nebulosity, the stars of
the cluster having been formed from the nebula's matter.
The
complex has the following NGC designations:
-
NGC 2237 Part of the
nebulous region (Also used to denote whole nebula)
-
NGC 2238 Part of the
nebulous region
-
NGC 2239 Part of the
nebulous region (Discovered by John
Herschel)
-
NGC 2244 The open
cluster within the nebula (Discovered by John
Flamsteed in 1690)
-
NGC 2246 Part of the
nebulous region
The
cluster and nebula lie at a distance of some 5,200 light
years from Earth (although
estimates of the distance vary considerably) and measure
roughly 130 light years in diameter. The radiation from
the young stars excite the atoms in
the nebula, causing them to emit radiation themselves
producing the emission nebula we see. The mass of
the nebula is estimated to be around 10,000 solar
masses.
It is
believed that stellar winds from a group of O and B stars
are exerting pressure on interstellar clouds to cause
compression, followed by star formation in the nebula. This
star formation is currently still ongoing.
A
survey of the nebula with the Chandra
X-ray Observatory in 2001 has revealed the presence of
very hot, young stars at the core of the Rosette Nebula.
These stars have heated the surrounding gas to a temperature
in the order of 6 million Kelvin
causing them to emit copious amounts of X-rays.
The
text above is taken from
Wikipedia.
The
Halpha regions extending from the Rosette down and leftwards
makes up the beginning (or end?) of the Monoceros loop,
going from the Rosette to the Cone nebula.
The
processing of this image was difficult from a star point of
view. As I stretched the image got completely filled with
stars, hiding the nebula. The trick was to remove the stars
before stretching and then add the star layer below the
non-star layer and blend using lighten (in PS CS5).
The
following software has been used. MaximDL (image
acquisition), CCDStack (calibration and de-convolution),
PixInsight (cropping, background correction, colour
corrections) and Photoshop CS5 (all the rest, incl Noel
Carbonis Astronomy Tools).
Since this object is dominated by H alpha I used the red
channel as the luminance when doing the LRGB combine after
CCDStack calibration. The image was processed in January
2011, more than two years after it was taken.
An
enlarged image (50% of original) can be viewed
here. |
