CG 4: The Globule and the Galaxy
AI Summary2 min read
TL;DR
CG 4 is a cometary globule, a star-forming molecular cloud 1,300 light-years away, shaped like a comet with a 1.5-light-year head and 8-light-year tail. Its form may result from a supernova or massive stars, and it poses no threat to the distant galaxy ESO 257-19.
CG 4: The Globule and the Galaxy
Image Credit & Copyright: William Vrbasso
Text: Cecilia Chirenti (NASA GSFC, UMCP, CRESST II)
Explanation: Is this a cosmic monster ready to devour an unsuspecting galaxy? Thankfully, that is not the case. The red “monster” shown in the featured image is Cometary Globule CG 4, 1,300 light-years away in the Constellation Puppis. CG 4 is a molecular cloud, where hydrogen becomes cold enough to form molecules that can be brought together by gravity to create stars. The shape of CG 4 resembles that of a comet, but its head is 1.5 light-year in diameter and its tail is 8 light-years long; for comparison, the distance from the Earth to the sun is only 8 light-minutes. Astronomers believe that the tail of a cometary globule could have been shaped by a nearby supernova explosion or by irradiation from hot, massive stars. Indeed, CG 4 and other nearby globules point away from the Vela Supernova Remnant, at the center of the Gum Nebula. The edge-on spiral galaxy, ESO 257-19, is more than a hundred million light-years beyond CG 4, and is completely safe from the “monster”.