Starship Asterisk*

Carina Nebula North

Explanation: The Great Carina Nebula is home to strange stars and iconic nebulas. Named for its home constellation, the huge star-forming region is larger and brighter than the Great Orion Nebula but less well known because it is so far south -- and because so much of humanity lives so far north. The featured image shows in great detail the northern-most part of the Carina Nebula. Visible nebulas include the semi-circular filaments surrounding the active star Wolf-Rayet 23 (WR23) on the far left. Just left of center is the Gabriela Mistral Nebula consisting of an emission nebula of glowing gas (IC 2599) surrounding the small open cluster of stars (NGC 3324). Above the image center is the larger star cluster NGC 3293, while to its right is the relatively faint emission nebula designated Loden 153. The most famous occupant of the Carina Nebula, however, is not shown. Off the image to the lower right is the bright, erratic, and doomed star star known as Eta Carinae -- a star once one of the brightest stars in the sky and now predicted to explode in a supernova sometime in the next few million years.

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I really like today's APOD, even though it's a mapped color image. Yes, but not only does it bring out details in the nebula beautifully, as mapped color narrowband nebula images almost always do, but I also like the mapped colors as such. I'm particularly glad that hydrogen alpha is not mapped to a sickly green color in this image!

And how can you not like the Gabriela Mistral Nebula? Gabriela Mistral was a Chilean poet, diplomat, educator and humanist, and she won the Nobel Prize in Literature in 1945. Not only that, but she sure put her own portrait in the heavens, too! Just look at the picture at right. Surely you can see the resemblance?

A more formal name for the Gabriela Mistral Nebula is NGC 3324, and Hubble has snapped a remarkable picture of this nebula - or rather Hubble has snapped a remarkable picture of the long sharp-edged dust lane that creates the outline of the Chilean poet on the canvas of the sky:


Amazing, isn't it? I think Gabriela Mistral is lying face down in the image above. Do you think that elongated deep valley left of center could be her nose?

I said before that I really like today's APOD, and I do, but narrowband images are not ideal when it comes to portraying stars and star clusters. The great NGC 3293 star cluster deserves a better picture, and ESO has made a stunning BVIHα image of it:


It's lovely, isn't it? I think that NGC 3293 is one of the most beautiful open clusters in the sky. All right, the Double Cluster is certainly even more stunning, but you can't have everything!

Ann

Poor Eta; they say she gonna go boom some day!
This star amazed me since I first heard f it! I kinda wish it would
happen while I could view it! Oh My; what a pretty kitty!🥰

orin stepanek wrote: ↑Mon Jan 31, 2022 2:04 pm happen while I could view it!

I wonder if it would be at least a little dangerous to view such an event with your own eyes. Surely exposing one's eyes to high energy particles can't be all that healthy

rj rl wrote: ↑Mon Jan 31, 2022 7:13 pm

orin stepanek wrote: ↑Mon Jan 31, 2022 2:04 pm happen while I could view it!

I wonder if it would be at least a little dangerous to view such an event with your own eyes. Surely exposing one's eyes to high energy particles can't be all that healthy

I think it would be safe. Eta Carina is very far away, about 5,000 light-years. At such a distance, I don't think it would be really dangerous or blinding to watch this star go supernova.

But of course, I could be wrong. What do the rest of you think? Chris? Art? Anyone else?

Ann

Ann wrote: ↑Mon Jan 31, 2022 7:19 pm

rj rl wrote: ↑Mon Jan 31, 2022 7:13 pm

orin stepanek wrote: ↑Mon Jan 31, 2022 2:04 pm happen while I could view it! :evil:

I wonder if it would be at least a little dangerous to view such an event with your own eyes. Surely exposing one's eyes to high energy particles can't be all that healthy :roll:

I think it would be safe. Eta Carina is very far away, about 5,000 light-years. At such a distance, I don't think it would be really dangerous or blinding to watch this star go supernova.

But of course, I could be wrong. What do the rest of you think? Chris? Art? Anyone else?

Ann

In terms of absolute magnitude the SN (at around -19) would be more than a billion times brighter than the Sun (at 4.83). But at 5000 ly away, it would have its intensity reduced by a factor of 10¹⁷. So its apparent magnitude would be -6. A few times brighter than Venus.

The Wikipedia articles for NGC 3324 and NGC 2393 say the two clusters are "associated", in that

Both are fairly young, at around 12 million years old. They show some degree of mass segregation, with more massive stars concentrated near their centers. Neither are dynamically relaxed.[2]

But other than that, are they gravitationally interacting or thought to share an origin from the "same" interstellar gas cloud? The Carina Nebula is thought to be only 230 ly in radius* (460 ly in diameter), and the two clusters are supposedly 700 ly apart* (using the figures from that inerrant source Wikipedia).

*EDIT: corrected to be radius instead of diameter, and 700 ly apart instead of 600 [Thanks, De58te!]

johnnydeep wrote: ↑Mon Jan 31, 2022 8:11 pm The Carina Nebula is thought to be only 230 ly in diameter, and the two clusters are supposedly 600 ly apart (using the figures from that inerrant source Wikipedia).

Correction. The wikipedia article states the size of the Carina Nebula is 230 ly radius. That means the diameter is 460 ly. Also its distance from Earth is approx 7,500 ly while the star cluster NGC 3293 is 8,400 ly away, and NGC 3324 is 9,100 ly away. Now if it assumed that the two star clusters and the nebula were associated, then that means millions of years ago the Carina Nebula was much deeper in size than what we see from Earth today! Maybe we are looking at it on its narrower side?

De58te wrote: ↑Mon Jan 31, 2022 8:42 pm

johnnydeep wrote: ↑Mon Jan 31, 2022 8:11 pm The Carina Nebula is thought to be only 230 ly in diameter, and the two clusters are supposedly 600 ly apart (using the figures from that inerrant source Wikipedia).

Correction. The wikipedia article states the size of the Carina Nebula is 230 ly radius. That means the diameter is 460 ly. Also its distance from Earth is approx 7,500 ly while the star cluster NGC 3293 is 8,400 ly away, and NGC 3324 is 9,100 ly away. Now if it assumed that the two star clusters and the nebula were associated, then that means millions of years ago the Carina Nebula was much deeper in size than what we see from Earth today! Maybe we are looking at it on its narrower side?

Thanks for the correction. I fixed my original post. Still not clear here what "associated" means in this context. And narrower side of the nebula or not, distance is distance and two things at distances D1 ly and D2 ly from our POV can't be any closer than |D1-D2| ly apart spatially. Of course, the distance estimates might not be entirely rock solid.

rj rl wrote: ↑Mon Jan 31, 2022 7:13 pm

orin stepanek wrote: ↑Mon Jan 31, 2022 2:04 pm happen while I could view it!

I wonder if it would be at least a little dangerous to view such an event with your own eyes. Surely exposing one's eyes to high energy particles can't be all that healthy

when she blows how long do you suppose the flash will last? Maybe a couple of days?

orin stepanek wrote: ↑Mon Jan 31, 2022 10:59 pm

rj rl wrote: ↑Mon Jan 31, 2022 7:13 pm

orin stepanek wrote: ↑Mon Jan 31, 2022 2:04 pm happen while I could view it!

I wonder if it would be at least a little dangerous to view such an event with your own eyes. Surely exposing one's eyes to high energy particles can't be all that healthy

when she blows how long do you suppose the flash will last? Maybe a couple of days?

I found this picture showing the "typical" light curves of type I and type II supernovas:


Type I supernovas are those that don't show any hydrogen in their spectra. Usually these are exploding white dwarfs. Eta Carina is therefore not going to be a type I supernova, but a type II.

As you can see from the graph, type II supernovas are expected to reach their peak brightness soon after the explosion and then stay at their top luminosity for about a hundred days.

You can also see that supernovas type II are expected to be less luminous than supernovas type I. (I'd say that the type I supernova in the graph is a supernova of type Ia, which is indeed an exploding white dwarf.)

But supernovas type II release huge amounts of neutrinos, so I believe that the total energy released by a typical type II supernova exceeds the energy released by most type Ia supernovas. Type Ia supernovas are just (normally) visually brighter.

Remember that supernovas are different, and supernovas type II differ more from one another than supernovas type Ia. It is therefore not possible to say that supernovas type II are going to be exactly as luminous as the graph suggests they will be, or that they are going to last exactly as long. It seems likely that Eta Carina is going to be a very bright supernova, but I don't think we have any way of really knowing that.

I took the graph from this page, which talks about the properties of supernovas.

Ann

Ann wrote: ↑Tue Feb 01, 2022 6:30 am

orin stepanek wrote: ↑Mon Jan 31, 2022 10:59 pm

rj rl wrote: ↑Mon Jan 31, 2022 7:13 pm

I wonder if it would be at least a little dangerous to view such an event with your own eyes. Surely exposing one's eyes to high energy particles can't be all that healthy

when she blows how long do you suppose the flash will last? Maybe a couple of days?

I found this picture showing the "typical" light curves of type I and type II supernovas:

snlightcurves[1].gif

Type I supernovas are those that don't show any hydrogen in their spectra. Usually these are exploding white dwarfs. Eta Carina is therefore not going to be a type I supernova, but a type II.

As you can see from the graph, type II supernovas are expected to reach their peak brightness soon after the explosion and then stay at their top luminosity for about a hundred days.

You can also see that supernovas type II are expected to be less luminous than supernovas type I. (I'd say that the type I supernova in the graph is a supernova of type Ia, which is indeed an exploding white dwarf.)

But supernovas type II release huge amounts of neutrinos, so I believe that the total energy released by a typical type II supernova exceeds the energy released by most type Ia supernovas. Type Ia supernovas are just (normally) visually brighter.

Remember that supernovas are different, and supernovas type II differ more from one another than supernovas type Ia. It is therefore not possible to say that supernovas type II are going to be exactly as luminous as the graph suggests they will be, or that they are going to last exactly as long. It seems likely that Eta Carina is going to be a very bright supernova, but I don't think we have any way of really knowing that.

I took the graph from this page, which talks about the properties of supernovas.

Ann

Thanks Ann that is quite interesting!