Cometary Globules CG 30, CG 31 and CG 38 in Puppis Pictured against the sprawling star fields and dark clouds of the Southern constellation Puppis are some ghostly glowing structures known as cometary globules. They owe their existence to complex interactions between gas and dust and the intense ultraviolet radiation from young O type stars in their neighborhood. And possibly also to supernova explosions in the distant past. Passing shock waves and radiation pressure have interacted with density fluctuations in the interstellar medium, and caused the formation of condensations called Bok globules. The radiation is also ionizing Hydrogen gas in the area, visible as the faint pink glow, while slowly eroding away the condensed globules and blowing their contents out into long tails, similar to that of a comet. Radio observations from ESOs La Silla observatory in Chile have shown that the gas in the globules has a temperature of some 5,000 to 14,000 Kelvin. Within the dense globules new stars are being born and at least one of these is visible as a bright orange glow in the dense upper right globule CG 30. This is a Herbig-Haro object (HH120); the result of plasma jets ejected from young protostars which collide with the surrounding gas and dust and cause the glowing emission. These delicate light-year wide structures are relatively short lived and will ultimately succumb to the emerging radiation pressure from the very stars born within them. Within a few hundred thousand years a splendid cluster of young bright stars will emerge and take their place. This particular region in the southern constellation of Puppis is very rich. Surrounding the globules are faint dark clouds and countless stars in all colors. The beautiful little blue reflection nebula on the left is Bran 106/vdB-Ha 5.
Posted on: Sat, 22 Mar 2014 20:44:44 +0000
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