APOD: NGC 253: Dusty Island Universe (2014 Jul 26)

[APOD Robot]

NGC 253: Dusty Island Universe

Explanation: Shiny NGC 253 is one of the brightest spiral galaxies visible, and also one of the dustiest. Some call it the Silver Dollar Galaxy for its appearance in small telescopes, or just the Sculptor Galaxy for its location within the boundaries of the southern constellation Sculptor. First swept up in 1783 by mathematician and astronomer Caroline Herschel, the dusty island universe lies a mere 10 million light-years away. About 70 thousand light-years across, NGC 253 is the largest member of the Sculptor Group of Galaxies, the nearest to our own Local Group of Galaxies. In addition to its spiral dust lanes, tendrils of dust seem to be rising from a galactic disk laced with young star clusters and star forming regions in this sharp color image. The high dust content accompanies frantic star formation, earning NGC 253 the designation of a starburst galaxy. NGC 253 is also known to be a strong source of high-energy x-rays and gamma rays, likely due to massives black hole near the galaxy's center.

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[owlice]

Oh, that's a lovely image! Great explanation, too.

[Ann]

One of the great things about Astronomy Picture of the Day is that it often shows aspects of the universe that are close to home and easy to understand for the general public. Recent examples are a rocket launch, a New York City sunset or Manhattan as Stonehenge, iridescent clouds over Nepal, noctilucent clouds over London, a spotty sunrise over Brisbane, auroras over northern Canada, the Moon eclipses Saturn, Alicante Beach Moonrise, a solar filament erupts, spacecraft Rosetta shows comet has two components, and a cave with aurora skylight. All these APODs teach the public about the cosmos by staying on the Earth or at least by venturing no farther than the solar system.

Another recent APOD certainly strayed from the solar system, but only as far as it had to go to show us the nearast object of its kind: Gliese 832c, the nearast potentially habitable exoplanet. Today's APOD is slightly similar. No, NGC 253 is certainly not the nearest galaxy to our own, as it isn't even part of the Local Group of galaxies. It isn't even the nearest starburst galaxy, as dwarf galaxy IC 10 is probably only two million light-years from us. But NGC 253 is the brightest galaxy of the Sculptor group, which is the nearest galaxy group outside the Local Group. And for the amateur observer NGC 253 is definitely one of the best galaxies.

http://www.thefreelibrary.com/NGC+253-- ... 0357035774 wrote:

Many galaxies vie for the title 'best in sky' and the choice is obviously very subjective, but there is no doubting that for many observers NGC 253 would be close to the top of their list.
...
Some observers claim it is a naked eye object, and while this may only be true under a really good sky with the galaxy overhead, it is certainly a stunning sight in any form of optical aid.

So if you live in the southern hemisphere, or if you live in the southern part of the northern hemisphere, grab your binoculars and go NGC 253-hunting!

For me as a lover of great galaxy photographs, NGC 253 is relatively non-photogenic in pictures. It doesn't show an obvious central dust lane like NGC 1032. It doesn't show a fat bulge like M104. It doesn't show an obvious bar like NGC 7741. It doesn't show a fantastic ring like M94. It doesn't show splendid spiral arms like NGC 2857. It doesn't show a great outflow of gas from its center like another nearby starburst galaxy, M82. To me it looks mostly oval and chaotic.

But lucky you if you live in the southern hemisphere and haven't seen it yet in the skies above you!

Ann

[NGC3314]

NC 253 does look more organized elsewhere in the spectrum. Going into the infrared, it has a pretty prominent two-armed pattern, with a bar and probably an inner ring - shown, for example, in Spitzer data:



To my surprise, these also appear in H-alpha images when the continuum starlight is subtracted, even with all those dust patches chopping up the view, seen in the attachment. This is one of those spirals where the structure as traced by star-forming regions and by dust lanes appears rather different (a point made at least as early as Sandage's Hubble Atlas around 1966).

[geckzilla]

Those are wonderful data, 3314. Sometimes I get upset with infrared for seeing through things too well but then you have this. I feel sorry for anyone who can't appreciate the invisible EM spectrum. Wonderful.

[Ann]

Thank you, NGC 3314!

Ann

[ta152h0]

When the writers of APOD use the word " dust " , is that dust of the same make up as the " cloud of dust " I leave behind when I go offroad in my F250 ?

[bystander]

When the writers of APOD use the word " dust " , is that dust of the same make up as the " cloud of dust " I leave behind when I go offroad in my F250 ?

No, they are referring to cosmic dust.

[Chris Peterson]

When the writers of APOD use the word " dust " , is that dust of the same make up as the " cloud of dust " I leave behind when I go offroad in my F250 ?

It's not dissimilar. Both are primarily small silicate particles, although they are of quite different history (although the same fundamental origin).

[Boomer12k]

Great image. I wonder what the Dust of our Galaxy looks like from afar???

:---[===] *

[Chris Peterson]

Great image. I wonder what the Dust of our Galaxy looks like from afar???

Depends on what wavelength you look in. Up close, and in visible light, you can see it on any clear night as the structure in the Milky Way.

[neufer]

When the writers of APOD use the word " dust " , is that dust of the same make up as the " cloud of dust " I leave behind when I go offroad in my F250 ?

Probably more amorphous : i.e, fewer crystals.

Also more iron (which has mostly sunk to the center of our planet).

[starsurfer]

NC 253 does look more organized elsewhere in the spectrum. Going into the infrared, it has a pretty prominent two-armed pattern, with a bar and probably an inner ring - shown, for example, in Spitzer data:



To my surprise, these also appear in H-alpha images when the continuum starlight is subtracted, even with all those dust patches chopping up the view, seen in the attachment. This is one of those spirals where the structure as traced by star-forming regions and by dust lanes appears rather different (a point made at least as early as Sandage's Hubble Atlas around 1966).

NGC253hagh1rotx.jpg

Considering this galaxy is starburst, I'm surprised any amateurs haven't taken any HaLRGB images of it?!