APOD: Portrait of NGC 281 (2014 Nov 28)

Comments and questions about the APOD on the main view screen.
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APOD Robot
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APOD: Portrait of NGC 281 (2014 Nov 28)

Post by APOD Robot » Fri Nov 28, 2014 5:07 am

Image Portrait of NGC 281

Explanation: Look through the cosmic cloud cataloged as NGC 281 and you might miss the stars of open cluster IC 1590. But, formed within the nebula, that cluster's young, massive stars ultimately power the pervasive nebular glow. The eye-catching shapes looming in this portrait of NGC 281 are sculpted columns and dense dust globules seen in silhouette, eroded by intense, energetic winds and radiation from the hot cluster stars. If they survive long enough, the dusty structures could also be sites of future star formation. Playfully called the Pacman Nebula because of its overall shape, NGC 281 is about 10,000 light-years away in the constellation Cassiopeia. This sharp composite image was made through narrow-band filters, combining emission from the nebula's hydrogen, sulfur, and oxygen atoms in green, red, and blue hues. It spans over 80 light-years at the estimated distance of NGC 281.

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somebodyshort
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Re: APOD: Portrait of NGC 281 (2014 Nov 28)

Post by somebodyshort » Fri Nov 28, 2014 7:11 am

Couple of questions:

1) Why do they always show these using narrow band filters for hydrogen and oxyen? Is it that it's the basis for water.
2) Why the narrow band for sulfur?
3) I take it any element higher than hydrogen is formed in a star. Clouds of higher elements are remnants for a star.
4) If those assumptions are correct, then the nebula is the result of a star's death distorted by solar winds and galactic rotation.
5) I assume all of the other elements are there, just not photographed, or at least presented. Heavier elements are produced during the super nova phase.
6) If 4) is correct then the mass of the nebula must be the mass of the dead star. That has to be near to or higher than the mass of a black hole. That would imply that a black hole has explosed, and that's scary.
7) On a different subject. Can one asume that dark matter coalesces along with the "normal" mater when forming stars and planets, adding to their total mass?

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Re: APOD: Portrait of NGC 281 (2014 Nov 28)

Post by geckzilla » Fri Nov 28, 2014 10:32 am

Those filters are used because it's just what's out there glowing. It's not to find water. There are other filters for scientific use but these just happen to be some of the most practical for imagery.
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Re: APOD: Portrait of NGC 281 (2014 Nov 28)

Post by BDanielMayfield » Fri Nov 28, 2014 11:31 am

Awesome image.
somebodyshort wrote:Couple of questions:
You ask way more than a couple, but questions are good. In fact, "question everything" is good advice.
3) I take it any element higher than hydrogen is formed in a star. Clouds of higher elements are remnants for a star.
Most of the helium and almost all of the lithium in space predate star formation, but in general, all elements higher than Li were produced in stars and in stellar explosions.
4) If those assumptions are correct, then the nebula is the result of a star's death distorted by solar winds and galactic rotation.
The nebula is mostly leftover gas mixed with heavier elements (metals) from many stars over the long history of our galaxy, not just one star's "death".

I'll leave the rest of your questions for others.

Bruce
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Re: APOD: Portrait of NGC 281 (2014 Nov 28)

Post by midas welby » Fri Nov 28, 2014 1:26 pm

When today's image opened on my monitor I immediately saw a face peering through the nebulosity. Awesome!

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Re: APOD: Portrait of NGC 281 (2014 Nov 28)

Post by BDanielMayfield » Fri Nov 28, 2014 6:50 pm

BDanielMayfield wrote:
somebodyshort wrote:Couple of questions:
I'll leave the rest of your questions for others.

Bruce
But since no one else has I'll resume now that I have the time.
somebodyshort wrote: 5) I assume all of the other elements are there, just not photographed, or at least presented. Heavier elements are produced during the super nova phase.
Yes, all the elements that are present in the earth and it's atmosphere would also be present in this nebula, in all likelihood. The elements heavier than iron and nickel are produced in supernovas, along with some lighter ones too. But some fraction of the elements between Li and Fe would have been cast off from stars that were not massive enough to ever go supernova.
6) If 4) is correct then the mass of the nebula must be the mass of the dead star. That has to be near to or higher than the mass of a black hole. That would imply that a black hole has explosed, and that's scary.
Again, this nebula wouldn't be from just one star. It is the eroded remains of a once much larger nebula, part of which has already condensed into a whole cluster of stars; IC 1590, which the discription says formed within the nebula. And don't be scared. There may not be any black holes in this area at all, and they don't explode, they just swallow things that get too close.
"Happy are the peaceable ... "

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Ron-Astro Pharmacist
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Re: APOD: Portrait of NGC 281 (2014 Nov 28)

Post by Ron-Astro Pharmacist » Fri Nov 28, 2014 7:41 pm

Other than it's obvious beauty and unique presentation, I really like the technique that Martin Pugh uses to display the variety of objects he photographs. Instead of sharp demarcations, the nebula's features gradually blend into the background of space and stars. Awhile back M1 was similarly portrayed (and, I'm sure, as many of the other images in his gallery are too). I don't know if this is similar to how our eye would see it, if they had the capability, but I would hope so. Today's APOD is like looking through a window to the universe. :clap:
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Re: APOD: Portrait of NGC 281 (2014 Nov 28)

Post by Chris Peterson » Fri Nov 28, 2014 9:34 pm

Ron-Astro Pharmacist wrote:Other than it's obvious beauty and unique presentation, I really like the technique that Martin Pugh uses to display the variety of objects he photographs. Instead of sharp demarcations, the nebula's features gradually blend into the background of space and stars. Awhile back M1 was similarly portrayed (and, I'm sure, as many of the other images in his gallery are too).
Without doubt, the processing is superb. But I don't think Martin is doing anything "artful" here. This is what the object looks like when imaged. Emission nebulas generally do blend into the background around the edge, and show their sharper edges and higher contrast features near the center.
Chris

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Re: APOD: Portrait of NGC 281 (2014 Nov 28)

Post by starsurfer » Fri Nov 28, 2014 10:16 pm

It is rather remarkable what can be achieved with long exposure times! Martin Pugh should image some planetary nebulae! They don't get enough attention and there's lots of obscure northern ones that have never been imaged in clear detail. At least Don Goldman is giving attention to unphotographed southern planetary nebulae.

Also it would be nice if all the images Martin Pugh has produced were in his website gallery.

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Re: APOD: Portrait of NGC 281 (2014 Nov 28)

Post by Boomer12k » Fri Nov 28, 2014 10:59 pm

What a great image....more "pillars of creation"...

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Re: APOD: Portrait of NGC 281 (2014 Nov 28)

Post by somebodyshort » Sun Nov 30, 2014 6:50 am

Thank you much appreciated