Starship Asterisk*

The Gum Nebula Supernova Remnant

Explanation: Because the Gum Nebula is the closest supernova remnant, it is actually hard to see. Spanning 40 degrees across the sky, the nebula appears so large and faint that it is easily lost in the din of a bright and complex background. The Gum Nebula is highlighted nicely in red emission toward the right of the featured wide-angle, single-image photograph taken in late May. Also visible in the frame are the Atacama Desert in Chile in the foreground, the Carina Nebula in the plane of our Milky Way galaxy running diagonally down from the upper left, and the neighboring Large Magellanic Cloud (LMC) galaxy. The Gum Nebula is so close that we are much nearer the front edge than the back edge, each measuring 450 and 1500 light years respectively. The complicated nebula lies in the direction of the constellations of Puppis and Vela. Oddly, much remains unknown about the Gum Nebula, including the timing and even number of supernova explosions that formed it.

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APOD Robot wrote:
The Gum Nebula is so close that we are much nearer the front edge than the back edge, each measuring 450 and 1500 light years respectively.

That's certainly fascinating!

Anyway. The Gum Nebula is faint, which is why we don't often see it being photographed. The nebulas at upper left in this APOD, the Carina Nebula and also the Running Chicken Nebula, are bright, and they are also much more distant, at an approximate distance of 7,500 light-years.

It is interesting that the upper to upper left part of the Gum Nebula (as seen in this APOD) is quite dark.

Wikipedia wrote:
The Gum Nebula (Gum 12) is an emission nebula that extends across 36° in the southern constellations Vela and Puppis. It lies approximately 450 parsecs from the Earth. Hard to distinguish, it was widely believed to be the greatly expanded (and still expanding) remains of a supernova that took place about a million years ago. More recent research suggests it may be an evolved H II region. It contains the 11,000-year-old Vela Supernova Remnant, along with the Vela Pulsar.

More recent research suggests that the Gum Nebula may be an evolved H II region? Really?

The Gum Nebula contains about 32 cometary globules. These dense cloud cores are subject to such strong radiation from O-type stars γ2 Vel and ζ Pup and formerly the progenitor of the Vela Supernova Remnant that the cloud cores evaporate away from the hot stars into comet-like shapes. Like ordinary Bok globules, cometary globules are believed to be associated with star formation.

So hot O-type stars Gamma Velorum and Zeta Puppis affect the Gum nebula. They shape cometary globulas in the Gum Nebula, but they also inject energy into the large nebula and certainly help ionize parts of it.

Perhaps the dark part of the Gum Nebula is shielded from the harsh ultraviolet light from Gamma Velorum and Zeta Puppis?

Ann

I found an interesting hydrogen alpha image of the Gum Nebula:


Fascinating!

Ann

I like it where it says "We are much nearer to the front edge than the back edge." So this means in other words that something 450 light years away is closer to us than something 1,500 light years away. (It makes me feel good that the money I spent on a college tuition was well spent.)

Very interesting Nebula! The business end of a dog! Watch out where he pokes it

De58te wrote: ↑Tue Nov 29, 2022 11:39 am I like it where it says "We are much nearer to the front edge than the back edge." So this means in other words that something 450 light years away is closer to us than something 1,500 light years away. (It makes me feel good that the money I spent on a college tuition was well spent.)

Well, to be fair, we are ALWAYS nearer the front edge of any object than the back edge!

If supernovas trigger star formation, Gum wasn’t our mother.

Which one was is shaping new science.

Ann wrote: ↑Tue Nov 29, 2022 7:28 am
That's certainly fascinating!

Anyway. The Gum Nebula is faint, which is why we don't often see it being photographed.

Ann

Fascinating and somewhat disconcerting! This thing is about 1000 ly wide (1500-450), some one hundredth of the Milky Way extension! I bet it is faint, it must have a really low density. I don't even know how can you can take a picture of it. And it reached this size in about one million years, so at a speed of about 300km/s, if my calculations are right.

Chris Peterson wrote: ↑Tue Nov 29, 2022 3:42 pm

De58te wrote: ↑Tue Nov 29, 2022 11:39 am I like it where it says "We are much nearer to the front edge than the back edge." So this means in other words that something 450 light years away is closer to us than something 1,500 light years away. (It makes me feel good that the money I spent on a college tuition was well spent.)

Well, to be fair, we are ALWAYS nearer the front edge of any object than the back edge!

Indeed. The wording seemed strange to me too, but I believe the intent was to show that the ratio of the back edge to the front edge is significantly greater than one! That is, 1500/450 > 3, whereas, say, 11500/10450 is pretty close to 1 (which is what the ratio would be if the nebula was 10000 ly farther away).

So, anyone figure out how to use the angle tool linked to in the text? Sure, it displays an angle that you type in or indicate with your mouse, but how do you use it to measure an angle on another web page?