Image Credit: ESO/Digitized Sky Survey 2/N. Risinger (
skysurvey.org)
In a brand-spankin' new image from the European Southern Observatory (ESO), we come across a rich treasure trove of objects lurking within the constellation of Ara—roughly 4,000 light-years from Earth.
The larger region—which, as a whole, is called the
Rim Nebula—contains various objects with different classifications, including star clusters, a few emission nebulae and, of course, too many active star forming regions to count. This particular image of the Rim Nebula is the most detailed ever captured, taken as a part of the Very Large Survey Telescope.
Honing in on different features, we primarily encounter a bright open cluster of stars called NGC 6193, which contains somewhere around 30 stars, which, in turn, form the
Ara OB1 Association. Naturally, in addition to their brightness, they are extremely hot, which makes the affect they have on their surroundings all the more powerful. Specifically, two of the stars are primarily responsible for the emission nebulae at the heart of the nebular cloud.
[box style="0"] A stellar association is a large grouping of loosely bound stars that have not yet completely drifted away from their initial formation site. OB associations consist largely of very young blue–white stars, which are about 100 000 times brighter than the Sun and between 10 and 50 times more massive.
The Rim Nebula is the prominent wall of dark and bright clouds marking the boundary between an active star-forming region within the molecular cloud, known as RCW 108, and the rest of the association. The area around RCW 108 is made up of mostly hydrogen—the primary ingredient in star formation. Such areas are also known as H II regions.
The ultraviolet radiation and intense stellar wind from the stars of
NGC 6193 seem to be driving the next generation of star formation in the surrounding clouds of gas and dust. As cloud fragments collapse they heat up and eventually form new stars.
As the cloud creates new stars, it is simultaneously being eroded by the winds and radiation emitted by previous stars, and by violent supernova explosions. In this way, such star-forming H II regions tend to have a lifespan of just a few million years. Star formation is a very inefficient process, with only around 10% of the available material contributing to the process—the rest is blown off into space.
The Rim Nebula also shows signs of being in the early phase of “pillar formation”, meaning that in the future it could end up looking similar to other well-known star-forming regions, such as the
Eagle Nebula (Messier 16, containing the famous
Pillars of Creation) and the
Cone Nebula (part of NGC 2264). [/box]
Like most iconic images, this one was put together using nearly 500 individual images taken at different parts of the electromagnetic spectrum. In this case, 4 different filters were used. Overall, 56 hours of telescope time was devoted to them.
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