DECam makes surprising discovery of comet-like structures within the Gum Nebula

An astronomer using dark energy camera (DECam) on NSF’s Victor M. Blanco 4-meter Telescope at the Cerro Toloro Inter-American Observatory, a program of NSF’s NOIRLab, imaged a dark and dusty cometary globule known as CG4.

Comet globules are faint, small clouds of gas and dust in the Milky Way.

These objects were first recognized in photographs taken with the British Schmidt telescope in Australia in 1976, but their faintness makes them particularly difficult targets for color photography.

Comet globule CG4, also known as the “Hand of God,” is located approximately 1,300 light-years away in the constellation Sulina.

The diameter of the head is about 1.5 light years, and the length of the tail is about 8 light years.

This dusty cloud contains enough material to form several stars the size of our Sun.

“Cometary globules are a subclass of dark nebulae known as bok globules, which are isolated clouds of dense cosmic gas and dust surrounded by hot ionized material,” NOIRLab astronomers said in a statement. mentioned in.

“When these clouds exhibit exfoliations of material that extend tails, they are called comet globules because they vaguely resemble comets, although they have nothing in common.”

“The features that classify CG4 as a cometary globule will be hard to miss in the new images.”

“With a dusty head 1.5 light-years in diameter and a long, wispy tail about 8 light-years long, CG4 is a relatively small bok globule, a common feature of comet globules.”

“The comet globule, first recognized in a photograph taken with the British Schmidt telescope in Australia in 1976, was so faint that it went undetected by astronomers for a long time,” they added.

“Their tails are covered in dark star dust that blocks out most of the light.”

“However, by using a special Hydrogen Alpha filter, DECam is able to pick up the faint red glow of ionized hydrogen present within the head of CG4 and around its outer edges.”

“This light is produced when hydrogen is excited by radiation from a nearby hot, massive star.”

“But the intense radiation produced by these neighboring massive stars is gradually destroying the heads of the spherules and cleaning out the tiny particles that scatter the starlight.”

“Yet, CG4’s dusty cloud contains enough gas to feed the active formation of several new Sun-sized stars.”

Astronomers have observed these structures throughout the Milky Way, but the vast majority of them, including CG4, rubber nebula.

The Gum Nebula, believed to be the expanding remnant of a supernova that occurred about a million years ago, is now known to contain at least 31 comet globules in addition to CG4.

The mechanism by which these comet-like objects acquire their unique shapes is not completely understood, but astronomers have developed two main ideas about their origin.

The first idea is that they may have originally been globular nebulae, like the well-known Ring Nebula, and were then destroyed by a nearby supernova explosion, perhaps the first explosion that produced the Gum Nebula. There is a possibility that

A second idea is that comet globules are formed by a combination of stellar winds and radiation pressure from nearby hot, massive stars.

In fact, all comet globules found within the Gum Nebula appear to have tails pointing away from the nebula’s center. The Bella supernova remnant and the Bella pulsar are located there.

Bella pulsars are fast-spinning neutron stars formed when massive stars collapse, and their stellar winds and radiation pressure may have formed nearby spherules.

“The new images also show that CG4 appears to be about to swallow the spiral galaxy directly beside it.” ESO257-19“It appears to be left too vulnerable in front of it,” the researchers said.

“But in reality, this galaxy is more than 100 million light-years further away than CG4, and only a coincidental alignment makes it appear closer.”