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NGC 3603 and NGC 3576 - Spectacular Landscape of Star
Formation in Carina |
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Short Object description:
To the east of the Carina nebula, there are two other
areas of star formation inside the southern milky way. The nebula around NGC
3576 on the right hand side of the image is about 7800 light years away from
the Earth. The two arched structures in the northern part of the Nebula are a
very remarkable feature. The intensive star winds of the massive young stars in
the center of the nebula produce the bubble-like structures in the gas clouds.
The nebula Gum 38b (around the extremely luminous star cluster NGC 3603
on the left hand side) is about 23.000 light years away. The color of the
nebula is significantly shifted into a orange-reddish hue when it is compared
to NGC 3576. This is caused by a more intensive interstellar absorption due to
the longer light path. |
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Click here or the thumbnail image for the object
identification and a comparison with the size of the Moon. |
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NGC 3603 is a very bright star
cluster and is famed for having the highest concentration of massive stars that
have been discovered in our galaxy so far. At the centre lies a WolfRayet
multiple star system, known as HD 97950. WolfRayet stars are at an
advanced stage of stellar evolution, and start off with around 20 times the
mass of the Sun. But, despite this large mass, WolfRayet stars shed a
considerable amount of their matter due to intense stellar winds, which blast
the stars surface material off into space at several million kilometres
per hour, a crash diet of cosmic proportions.
NGC 3603 is in an area of very active star formation.
Stars are born in dark and dusty regions of space, largely hidden from view.
But as the very young stars gradually start to shine and clear away their
surrounding cocoons of material they become visible and create glowing clouds
in the surrounding material, known as HII regions. HII regions shine because of
the interaction of ultraviolet radiation given off by the brilliant hot young
stars with the hydrogen gas clouds. HII regions can measure several hundred
light-years in diameter, and the one surrounding NGC 3603 has the distinction
of being the most massive in our galaxy
» NGC 3603 -
Multispectralimage (V, R, I) FORS-Instrument at the VLT ©
ESO Click
here
or the thumbnail to see a large image. |
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The cluster
was first observed by John Herschel on 14 March 1834 during his three-year
expedition to systematically survey the southern skies from near Cape Town. He
described it as a remarkable object and thought that it might be a globular
star cluster. Today we know that it is not an old globular, but a young open
cluster, one of the richest known. |
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NGC 3576 also lies in the
CarinaSagittarius spiral arm of the Milky Way. But it is located only
about 9000 light years from Earth - much closer than NGC 3603, but appearing
next to it in the sky.
NGC 3576 is notable for two huge curved objects
resembling the curled horns of a ram. These odd filaments are the result of
stellar winds from the hot, young stars within the central regions of the
nebula, which have blown the dust and gas outwards across a hundred light
years. Two dark silhouetted areas known as Bok globules (marked with circles)
are also visible in this vast complex of nebulae. These black clouds near the
top of the nebula also offer potential sites for the future formation of new
stars. Such black clouds can also found in other H-II regions, so as an example
in
IC 2944
« The
image at left shows a high resolution comparison at nearly same scale of
the region around the Bok globules. The left image |
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(BW-negative) was taken by us, using the 150mm Zeiss APQ, a SBIG
ST-2000 (two images at 1.800 seconds) and a Baader narrow band H-alpha filter.
The colour version was taking with the Wide Field Imager-Camera at
La-Silla-Observatory/ ESO aufgenommen (© ESO)
Click here or the thumbnail to see a larger image.
NGC 3576 was also discovered by John Herschel in 1834, making it a
particularly productive and visually rewarding year for the English astronomer
in South Africa. |
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