APOD: Portrait of NGC 1055 (2024 Mar 15)

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APOD: Portrait of NGC 1055 (2024 Mar 15)

Post by APOD Robot » Fri Mar 15, 2024 4:06 am

Image Portrait of NGC 1055

Explanation: Big, beautiful spiral galaxy NGC 1055 is a dominant member of a small galaxy group a mere 60 million light-years away toward the aquatically intimidating constellation Cetus. Seen edge-on, the island universe spans over 100,000 light-years, a little larger than our own Milky Way galaxy. The colorful, spiky stars decorating this cosmic portrait of NGC 1055 are in the foreground, well within the Milky Way. But the telltale pinkish star forming regions are scattered through winding dust lanes along the distant galaxy's thin disk. With a smattering of even more distant background galaxies, the deep image also reveals a boxy halo that extends far above and below the central bulge and disk of NGC 1055. The halo itself is laced with faint, narrow structures, and could represent the mixed and spread out debris from a satellite galaxy disrupted by the larger spiral some 10 billion years ago.

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Ann
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Re: APOD: Portrait of NGC 1055 (2024 Mar 15)

Post by Ann » Fri Mar 15, 2024 7:07 am

Image133k_n1055_1024[1].jpg
Portrait of NGC 1055
Image Credit & Copyright: Dave Doctor

I like this APOD, but I'm a bit critical, too.

A very good thing is that NGC 1055 gets highlighted in the first place. This galactic denizen of Cetus is hardly one of those galaxies that gets too much limelight! In the case of NGC 1055, its limelight is usually stolen by its Messier galaxy neighbor, M77:


An interesting thing is that we can see in the APOD is NGC 1055's bright and irregular halo. There is what almost looks like a jet, or more likely a fat stellar stream, rising from the galaxy at upper left. And we can see what looks like a bluish stellar disk extending to the right from the galaxy.

Speaking of the halo (or the bulge), I can't resist showing you these two Spitzer Space Telescope infrared images of the bulge of NGC 1055:



Fatso! :yes:

The foreground stars add interest. It's not that common to find three differently colored "bright-but-not-too-bright" stars so close to a galaxy. Of course, the stars are not as colorful as you may be led to believe. Well, there is a really colorful bright blue star in the direction of NGC 1055 and M77, and that is B2IV type star delta Ceti!


Let me return to the APOD. I wish that the disk of NGC 1055 had been a little better resolved and a little more colorful.
APOD Robot wrote:
But the telltale pinkish star forming regions are scattered through winding dust lanes along the distant galaxy's thin disk.
The "telltale pinkish star forming regions" are hard to spot in the APOD. You can see them in this picture from ESO, where you can also see blue star clusters:


Finally, let me show you three mostly face-on galaxies in the direction of NGC 1055 and M77. The galaxies may or may not be at the same distance from us as M77 and NGC 1055.


No, wait! Before I go, I just have to show you a edge-on galaxy that is really something else (I mean, in view of the fact that NGC 1055 is an edge-on galaxy)!



Ann
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Re: APOD: Portrait of NGC 1055 (2024 Mar 15)

Post by Christian G. » Fri Mar 15, 2024 12:19 pm

With that pair of bluish and goldish stars straight beneath it almost looks like a galaxy sitting on top of Albireo, lovely effect!

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Re: APOD: Portrait of NGC 1055 (2024 Mar 15)

Post by johnnydeep » Fri Mar 15, 2024 6:36 pm

Thanks, Ann. The image of UGC 12591 is truly spectacular! Just as awesome as those deep images of the Sombrero Galaxy!

I assume we are seeing UGC 12591's "underside" from our POV.

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Re: APOD: Portrait of NGC 1055 (2024 Mar 15)

Post by johnnydeep » Fri Mar 15, 2024 6:39 pm

Christian G. wrote: Fri Mar 15, 2024 12:19 pm With that pair of bluish and goldish stars straight beneath it almost looks like a galaxy sitting on top of Albireo, lovely effect!
For the context of that apt reference, see:
https://en.wikipedia.org/wiki/Albireo wrote: Albireo /ælˈbɪrioʊ/[19] is a double star designated Beta Cygni (β Cygni, abbreviated Beta Cyg, β Cyg).

Beta Cygni is about 420 light-years (129 pc) away from the Sun.[2] When viewed with the naked eye, Albireo appears to be a single star. However, in a telescope it resolves into a double star consisting of β Cygni A (amber, apparent magnitude 3.1), and β Cygni B (blue-green, apparent magnitude 5.1).[30] Separated by 35 seconds of arc,[11] the two components provide one of the best contrasting double stars in the sky due to their different colors.

It is not known whether the two components β Cygni A and B are orbiting around each other in a physical binary system, or if they are merely an optical double.[2] If they are a physical binary, their orbital period is probably at least 100,000 years.[30] Some experts, however, support the optical double argument, based on observations that suggest different proper motions for the components, which implies that they are unrelated.[31] The primary and secondary also have different measured distances from the Hipparcos mission – 434 ± 20 light-years (133 ± 6 pc) for the primary and 401 ± 13 light-years (123 ± 4 pc) for the secondary.[9] More recently the Gaia mission has measured distances of about 330–390 light years (100–120 parsecs) for both components, but noise in the astrometric measurements for the stars means that data from Gaia's second data release is not yet sufficient to determine whether the stars are physically associated.[32]
And:

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Re: APOD: Portrait of NGC 1055 (2024 Mar 15)

Post by Chris Peterson » Fri Mar 15, 2024 6:51 pm

johnnydeep wrote: Fri Mar 15, 2024 6:36 pm Thanks, Ann. The image of UGC 12591 is truly spectacular! Just as awesome as those deep images of the Sombrero Galaxy!

I assume we are seeing UGC 12591's "underside" from our POV.

How do you define "underside"? Would that be the "south" side, based on the convention that when you look down on the "north" pole of an object, you see it rotating counterclockwise?

Are we seeing the "topside" here?
_
UGC12951_HubbleShatz_960.jpg
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Re: APOD: Portrait of NGC 1055 (2024 Mar 15)

Post by johnnydeep » Fri Mar 15, 2024 7:07 pm

Chris Peterson wrote: Fri Mar 15, 2024 6:51 pm
johnnydeep wrote: Fri Mar 15, 2024 6:36 pm Thanks, Ann. The image of UGC 12591 is truly spectacular! Just as awesome as those deep images of the Sombrero Galaxy!

I assume we are seeing UGC 12591's "underside" from our POV.

How do you define "underside"? Would that be the "south" side, based on the convention that when you look down on the "north" pole of an object, you see it rotating counterclockwise?

Are we seeing the "topside" here?
_
UGC12951_HubbleShatz_960.jpg
Yeah, you're exactly right, of course. The unusual "underside" perspective here threw me off...Yeah, that's the ticket. Rotating the image 180° clearly would not magically make the underside the topside (i.e., the true other side that we will never see an image of!)
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Re: APOD: Portrait of NGC 1055 (2024 Mar 15)

Post by Ann » Fri Mar 15, 2024 7:28 pm

johnnydeep wrote: Fri Mar 15, 2024 6:39 pm
Christian G. wrote: Fri Mar 15, 2024 12:19 pm With that pair of bluish and goldish stars straight beneath it almost looks like a galaxy sitting on top of Albireo, lovely effect!
For the context of that apt reference, see:
https://en.wikipedia.org/wiki/Albireo wrote: Albireo /ælˈbɪrioʊ/[19] is a double star designated Beta Cygni (β Cygni, abbreviated Beta Cyg, β Cyg).

Beta Cygni is about 420 light-years (129 pc) away from the Sun.[2] When viewed with the naked eye, Albireo appears to be a single star. However, in a telescope it resolves into a double star consisting of β Cygni A (amber, apparent magnitude 3.1), and β Cygni B (blue-green, apparent magnitude 5.1).[30] Separated by 35 seconds of arc,[11] the two components provide one of the best contrasting double stars in the sky due to their different colors.

It is not known whether the two components β Cygni A and B are orbiting around each other in a physical binary system, or if they are merely an optical double.[2] If they are a physical binary, their orbital period is probably at least 100,000 years.[30] Some experts, however, support the optical double argument, based on observations that suggest different proper motions for the components, which implies that they are unrelated.[31] The primary and secondary also have different measured distances from the Hipparcos mission – 434 ± 20 light-years (133 ± 6 pc) for the primary and 401 ± 13 light-years (123 ± 4 pc) for the secondary.[9] More recently the Gaia mission has measured distances of about 330–390 light years (100–120 parsecs) for both components, but noise in the astrometric measurements for the stars means that data from Gaia's second data release is not yet sufficient to determine whether the stars are physically associated.[32]
And:

Interesting, Johnny. When I observed Albireo through a telescope, I was disappointed. I thought that the yellow primary star was pale, and the blue secondary star was also pale.

But when I observed 30 and 31 Cygni along with the 31 Cygni companion HD 192579, I was blown away. Because the yellow star, 31 Cygni, was noticeably more deeply yellow than the yellow component of Albireo. 30 Cygni was a sort of washed-out blue. But HD 192579 was absolutely intensely blue! Seeing the color contrast not between two stars, but between three stars, was incredible. It was fantastic to see the difference between a washed-out blue star, of spectral class A5, and an intensely blue star of spectral class B9, which was incredibly blue for its spectral class. (Indeed HD 192579 is incredibly blue for its spectral class, and I know it because I have checked its B-V index. HD 192579 could be a fast rotating pole on star, so that we see deep into its hot interior, which would make it extremely blue for its spectral class.) Anyway, seeing this trio was magical!

30 and 31 Cyg annotated Lodriguss.png
30 and 31 Cygni. HD 192579 is the blue star immediately
below orange 31 Cygni. Credit: Jerry Lodriguss.

And if you wonder about the small red star to the upper right of the letter "g" in the annotated image, I never noticed that star when I observed 30 and 31 Cygni. The red star is apparently TYC 3559-2491-1, and it is not as red as it looks. It is about the color of Arcturus.

The only star I've ever seen that blew me away with its deep red color is V Aquilae, a carbon star. It was unbelievably red!


If you check out the Simbad Astronomical Database, you can see that V Aquilae is only 11th magnitude (11.09) in B (blue) light, but magnitude 6.90, more than four magnitudes brighter, in V (yellow-green) light. You simply never see that kind of difference in magnitude between B and V light in any "normal" red giant star, not in Betelgeuse and not in Antares. Not even in mu Cephei, the famous "Garnet star". Only carbon stars are that red.

If you want to observe a carbon star for yourself, then T Lyrae might be a better option than V Aquilae. The difference between B and V magnitudes in T Lyrae is almost five magnitudes.

Ann
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