Starship Asterisk*

Ann wrote: ↑Tue May 21, 2024 4:49 am I always want to put things in perspective.

CG4: The Globule and the Galaxy. Image Credit: CTIO, NOIRLab, DOE, NSF, AURA; Processing: T. A. Rector (U. Alaska Anchorage/NSF’s NOIRLab), D. de Martin & M. Zamani (NSF’s NOIRLab)

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Why is that globule cometary? What made it open its mouth? Nearby hot bright stars, sure. What stars?

I found the coordinates for CG4, which is the name of this thing, and saw that it is located relatively close to Gamma Velorum, an enormous powerhouse in constellation Vela, the Sail. So I googled CG4 + Gamma Velorum and found... nothing.

This is the best I can do to show you where CG4 is in relation to Gamma Velorum:

Gamma Velorum (bright star at lower right) and the Vela supernova remnant. Credit: Robert Gendler, Roberto Colombari, Digitized Sky Survey (POSS II)

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Gama Velorum and this way to CG4 Gendler Columbari.png

This way to CG4.

To show you why it is important to put cometary globules into perspective, consider another such globule, the Dark Tower in Scorpius:

Dark Tower in Scorpius and NGC 6231 by Gerald Rhemann.png

The Dark Tower in Scorpius and star cluster NGC 6231.
Credit: Gerald Rehmann.

So, yeah. Perspective is important. Gerald Rehmann showed us why the Dark Tower in Scorpius and the massive open cluster NGC 6231 belong together. Now we really need a picture that shows us Gamma Velorum and CG4 in the same frame.

Oh, and... why has CG4 ruptured? How about Gamma Velorum released a jet of energy some time in the past, and CG4 took a direct hit? Perhaps the Wolf-Rayet component of Gamma Velorum had an outburst? It's a mean thing, Gamma Velorum.

And that galaxy that CG4 appears to be eating? Oh, it's PGC 21338, also known as ESO 257-19. It may have an active galactic nucleus, said Simbad. What's the distance to that thing? I don't know!

Ann

AVAO wrote: ↑Tue May 21, 2024 9:01 pm
ThanX Ann

Your hypothesis regarding gamma velorum is bold, but I also think correct.

Regarding the two YSOs, I find MASS_J073439.9-465548 (1) particularly noteworthy.
This seems to be in an intermediate stage and is almost floating freely in space.
According to the classical view, stripped of its dusty birth shell.

Click to view full size image

https://www.watson.ch/wissen/astronomie ... nkugel-cg4

NOIRLab wrote:

While astronomers have observed these structures throughout the Milky Way, the overwhelming majority of them, including CG 4, are found within a huge patch of glowing gas called the Gum Nebula. Believed to be the expanding remains of a supernova that took place about a million years ago, the Gum Nebula is currently known to contain at least 31 cometary globules in addition to CG 4.

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The second idea is that cometary globules are shaped by a combination of stellar winds and radiation pressure from nearby hot, massive stars. In fact, all of the cometary globules found within the Gum Nebula appear to have tails pointing away from the center of the nebula, which is where the Vela Supernova Remnant and Vela Pulsar are located. The Vela Pulsar is a rapidly spinning neutron star that was formed when a massive star collapsed, and it’s possible that its stellar winds and radiation pressure are shaping the nearby globules.