APOD: Nearby Spiral Galaxy NGC 4945 (2022 Feb 26)

[APOD Robot]

Nearby Spiral Galaxy NGC 4945

Explanation: Large spiral galaxy NGC 4945 is seen nearly edge-on in this cosmic galaxy close-up. It's almost the size of our Milky Way Galaxy. NGC 4945's own dusty disk, young blue star clusters, and pink star forming regions stand out in the colorful telescopic frame. About 13 million light-years distant toward the expansive southern constellation Centaurus, NGC 4945 is only about six times farther away than Andromeda, the nearest large spiral galaxy to the Milky Way. Though this galaxy's central region is largely hidden from view for optical telescopes, X-ray and infrared observations indicate significant high energy emission and star formation in the core of NGC 4945. Its obscured but active nucleus qualifies the gorgeous island universe as a Seyfert galaxy and home to a central supermassive black hole.

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[Ann]

NGC 4945 is a galaxy with several interesting features.

Nearby Spiral Galaxy NGC 4945. Image Credit & Copyright: Dietmar Hager, Eric Benson

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NGC 4945 has a somewhat disturbed disk. Note the strange dust cloud to the lower left of the nuclear region.

Note the two parallel lines of star formation with pink nebulas and blue clusters to the upper right of the nucleus.

Note that the star forming disk is lopsided. There appears to be more gas and dust to the upper right of the nuclear region than to the lower left of it. Note the "purely stellar disk" at lower left, which is completely devoid of gas and dust.

NGC 2976. Image: SDSS/Donald Pelletier

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Lopsided galaxy NGC 55. Photo: ESO.

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I'm reminded both of NGC 2976, which has a dusty starforming disk surrounded by a larger non-starforming purely stellar disk, and NGC 55, which has a lopsided disk quite rich in star formation. (Of course, in all other respects than the fact that NGC 2976 has a larger stellar disk surrounding its smaller dusty starforming disk, this galaxy is a complete oddball.)

NGC 253, the Silver Dollar Galaxy. Photo: ESO.

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James D Wray of The Color Atlas of Galaxies claimed that NGC 4549 is similar to bright edge-on dusty galaxy NGC 253. Yes, maybe, but I think that NGC 253 has a much "messier" disk than NGC 4945. (Even though "messier" NGC 253 isn't, but probably should have been, a Messier object. Joke of the day.)

Ann

[AVAO]

James D Wray of The Color Atlas of Galaxies claimed that NGC 4549 is similar to bright edge-on dusty galaxy NGC 253. Yes, maybe, but I think that NGC 253 has a much "messier" disk than NGC 4945. (Even though "messier" NGC 253 isn't, but probably should have been, a Messier object. Joke of the day.)

Well, degrees of order can be argued about.

(Credit: X-ray: NASA/CXC/Univ degli Studi Roma Tre/A.Marinucci et al, Optical: ESO/VLT & NASA/STScI)

Interesting nucleus in X-ray. Unfortunately, not much of this can be seen in the visible range.

(Credit: X-ray: NASA/CXC/Univ degli Studi Roma Tre/A.Marinucci et al, Optical: ESO/VLT & NASA/STScI)

[orin stepanek]

NGC4945; a beautiful galaxy; probably a lot like looking at
the Milky Way from space!

[MoonRockMan]

NGC4945-Dietmar-Eric-crop.jpg

I'm curious if anyone has identified any of the other galaxies in the image, like the one highlighted here, for instance. Beyond my capabilities

[Ann]

NGC4945-Dietmar-Eric-crop.jpg

I'm curious if anyone has identified any of the other galaxies in the image, like the one highlighted here, for instance. Beyond my capabilities

I, too, have been unsuccessful.

If you go to Simbad, you can actually see the galaxy, extremely faintly, to the right of NGC 4945. You can click on it to find out its coordinates, and you can ask Simbad to identify objects in the vicinity of NGC 4945. Well, I did so, and I had no luck. I believe that the galaxy in question is extremely faint, quite possibly fainter than 17th magnitude, and Simbad may simply not have a designation for it.

Ann

[Guest]

NGC4945-Dietmar-Eric-crop.jpg

I'm curious if anyone has identified any of the other galaxies in the image, like the one highlighted here, for instance. Beyond my capabilities

I, too, have been unsuccessful.

If you go to Simbad, you can actually see the galaxy, extremely faintly, to the right of NGC 4945. You can click on it to find out its coordinates, and you can ask Simbad to identify objects in the vicinity of NGC 4945. Well, I did so, and I had no luck. I believe that the galaxy in question is extremely faint, quite possibly fainter than 17th magnitude, and Simbad may simply not have a designation for it.

Ann

Very interesting! Thanks for the report

[alter-ego]

I'm curious if anyone has identified any of the other galaxies in the image, like the one highlighted here, for instance. Beyond my capabilities

I, too, have been unsuccessful.

If you go to Simbad, you can actually see the galaxy, extremely faintly, to the right of NGC 4945. You can click on it to find out its coordinates, and you can ask Simbad to identify objects in the vicinity of NGC 4945. Well, I did so, and I had no luck. I believe that the galaxy in question is extremely faint, quite possibly fainter than 17th magnitude, and Simbad may simply not have a designation for it.

Ann

Very interesting! Thanks for the report

Galaxies:
LEDA 3097829
ESO 219-25
6dFGS gJ130634.9-493149
 

[Guest]

I, too, have been unsuccessful.

If you go to Simbad, you can actually see the galaxy, extremely faintly, to the right of NGC 4945. You can click on it to find out its coordinates, and you can ask Simbad to identify objects in the vicinity of NGC 4945. Well, I did so, and I had no luck. I believe that the galaxy in question is extremely faint, quite possibly fainter than 17th magnitude, and Simbad may simply not have a designation for it.

Ann

Very interesting! Thanks for the report

Galaxies:
LEDA 3097829
ESO 219-25
6dFGS gJ130634.9-493149
 
NGC 4945.JPG

Wow, thank you so much! Those are a few of the ones I was looking at. Looking them up now

[alter-ego]

Very interesting! Thanks for the report

Galaxies:
LEDA 3097829
ESO 219-25
6dFGS gJ130634.9-493149
 
NGC 4945.JPG

Wow, thank you so much! Those are a few of the ones I was looking at. Looking them up now

You're welcome. At least you have identifiers, and I think the links will be helpful too.

[orin stepanek]

Very interesting! Thanks for the report

Galaxies:
LEDA 3097829
ESO 219-25
6dFGS gJ130634.9-493149
 
NGC 4945.JPG

Wow, thank you so much! Those are a few of the ones I was looking at. Looking them up now

Thanks for identifying it alter-ego ! For as large as it is in the photo; it's surprising that it is so faint!

[Ann]

I, too, have been unsuccessful.

If you go to Simbad, you can actually see the galaxy, extremely faintly, to the right of NGC 4945. You can click on it to find out its coordinates, and you can ask Simbad to identify objects in the vicinity of NGC 4945. Well, I did so, and I had no luck. I believe that the galaxy in question is extremely faint, quite possibly fainter than 17th magnitude, and Simbad may simply not have a designation for it.

Ann

Very interesting! Thanks for the report

Galaxies:
LEDA 3097829
ESO 219-25
6dFGS gJ130634.9-493149
 

Thanks a billion, alter-ego! How did you do that, when I couldn't?

Anyway. LEDA 3097829 is obviously a low surface brightness galaxy - not a tremendously low surface brightness galaxy, nothing like Malin 1, for example.

Malin 1, a low surface brightness galaxy. Image: SDSS/Giuseppe Donatiello

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Wikipedia wrote:

Malin 1 is a giant low surface brightness (LSB) spiral galaxy. It is located 1.19 billion light-years (366 Mpc) away in the constellation Coma Berenices, near the North Galactic Pole. As of February 2015, it is the largest known spiral galaxy, with an approximate diameter of 650,000 light-years (200,000 pc), thus over three times the diameter of our Milky Way. It was discovered by astronomer David Malin in 1986 and is the first LSB galaxy verified to exist. Its high surface brightness central spiral is 30,000 light-years (9,200 pc) across, with a bulge of 10,000 light-years (3,100 pc). The central spiral is a SB0a type barred-spiral.

But LEDA 3097829 is nothing like Malin 1. The giant low surface brightness galaxy in Coma Berenices has a high surface brightness central spiral, but LEDA 3097829 has a very faint center. Then again, its center is yellow and its outer regions bluish (or, more likely, just intermediate-colored). Also LEDA 3097829 has a very elegant barred shape. This suggests that LEDA 3097829 is reasonably massive, in order to display such mass segregation and such an elegant barred spiral shape. LEDA 3097829 actually resembles an extremely faint version of barred spiral galaxy NGC 7479:

LEDA 3097829.Photo: Dietmar Hager, Eric Benson.

NGC 7479. Photo: Göran Nilsson/The Liverpool Telescopes.

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An interesting difference between NGC 7479 and LEDA 3097829 is that the barred spiral shape of the latter appears to be superimposed on a larger, featureless disk. Alternatively, the blue-gray stuff surrounding the bar of LEDA 3097829 is a large bright halo.

In any case, my guess is that LEDA 3097829 is rich in dark matter, because the puny stellar content of the galaxy just doesn't seem enough to create its elegant shape.

Ann

[Chris Peterson]

Thanks a billion, alter-ego! How did you do that, when I couldn't?

Not sure where you went wrong. I you go to Simbad, find NGC 4945, and then do a query for 10 arcmin around that object, you'll see it highlighted in the image and can click on it to get the ID.
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