Anne’s Picture of the Day: The Elephant’s Trunk Nebula

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June 30, 2013

The Elephant’s Trunk Nebula, a dark globule within IC 1396

Image Credit: Lóránd Fényes, Best Newcomer in the Astronomy Photographer of the Year 2012 Competition

The Elephant’s Trunk Nebula (IC 1396A) is an elongated dark globule of more than 20 light-years long within the much larger (over 100 light-years across) emission nebula IC 1396 which is located about 2,400 light-years away in the northern constellation of Cepheus (named after the King of Aethiopia in Greek mythology). It was given this name as it resembles the head and trunk of an elephant.

The globule is a condensation of dense gas and dust that is being compressed by the intense radiation and stellar winds from the very bright, massive star HD 206267. The compression of the gas in the globule is triggering the formation of stars within it.

The stellar winds from the massive star are also responsible for sculpting and eroding the filaments of the globule. These winds produce a dense circular rim making up the “head” of the globule and a swept-back tail of gas. The dark globule is seen in silhouette in visible-light pictures, backlit by the illumination of HD 206267 which is located to the west of the “head”.

The Elephant’s Trunk nebula is a site of star formation. Over 250 young stars in and around the Elephant’s Trunk are identified. Several very young (less than 100,000 years old) stars and two older (but still young, a couple of million years) stars are present in a small, circular cavity in the head of the globule. Winds from these young stars may have emptied the cavity.

Very young protostars, still accreting material from the surrounding nebula, are located inside the cloud, while fully formed stars have been found just in front of the rims. This suggests that star formation has been proceeding sequentially through the cloud as a result of the ‘triggering’ effects of the hot star. On the order of 5% of the mass of gas and dust in the cloud has already been turned into protostars, and the process is continuing today.

This image was taken on May 8, 2011 with a Canon EOS 1000D on an Orion 8″ f/3.9 Newtonian Astrograph Reflector Telescope at Lake Balaton, Hungary.

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