Elephant's Trunk nebula

The Elephant's Trunk nebula is a concentration of interstellar gas and dust in the star cluster IC 1396 and ionized gas region located in the constellation Cepheus about 2,400 light years away from Earth [cite journal
last = Matthews
first = H. I.
authorlink = H. I. Matthews
title = High resolution radio observations of bright rims in IC 1396
journal = Astronomy and Astrophysics
year = 1979
volume = 75
pages = 345-350
url = http://adsabs.harvard.edu/abs/1979A%26A....75..345M] . The piece of the nebula shown here is the dark, dense globule IC 1396A; it is commonlycalled the Elephant Trunk nebula because of its appearance at visible wavelengths,where it is a dark patch with a bright, sinuous rim. The bright rim is the surface ofthe dense cloud that is being illuminated and ionized by a very bright, massive star thatis just to the west of IC 1396A. (In the Figure above, the massive star is just to the left of the edge of the image.) The entire IC 1396 region is ionized by the massive star,except for dense globules that can protect themselves from the star's harsh ultravioletrays.

The Elephant Trunk nebula is now thought to be site of star formation, containing several very young (less than 100,000 yr) stars that were discovered in infrared images in 2003. Two older (but still young, a couple of million years,by the standards of stars, which live billions of years) stars are present ina small, circular cavity in the head of the globule. Winds from these young stars may have emptied the cavity.

The combined action of the light from the massive star ionizing and compressingthe rim of the cloud, and the wind from the young stars shifting gas from the centeroutward lead to very high compression in the Elephant Trunk nebula. This pressurehas triggered the current generation of protostars.

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