IC 1396

IC 1396 is an emission nebula located about 2,400 light years from Earth in the constellation Cepheus.  Within the nebula is a dark, dense globule known as 1396A (shown below).  Oftentimes, this globule is called the Elephant’s Trunk Nebula, because of its sinuous appearance in optical light.  The edge of this dark patch appears bright, because it is being ionized by the massive triple system HD 206267.  In astronomical jargon, this makes IC 1396A a bright-rimmed cloud (BRC).

elephant_trunk

The Elephant’s Trunk nebula is thought to be a site of current active star formation.  A paper by Getman et al. (2012) identify more than 250 young stars in IC 1396A.  Furthermore, Getman et al. claim that there is a spatiotemporal gradient in the region.  Young stars appear to be clustered along the rim of the cloud.  Just inside the cloud, the stellar ages are estimated to be ≤ 1Myr.  Just in front of the cloud, the stellar ages are ~ 2-3 Myr.  Towards the Trumpler 37 cluster (of which HD 206267 is a member), the stellar ages are closer to 4 Myr.  The authors conclude that the majority of young stellar objects (YSOs) in the region formed through the same triggered star formation process that extended over 2 -3 Myr.

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