APOD: Galaxies in Pegasus (2020 Oct 15)

[APOD Robot]

Galaxies in Pegasus

Explanation: This sharp telescopic view reveals galaxies scattered beyond the stars of the Milky Way, at the northern boundary of the high-flying constellation Pegasus. Prominent at the upper right is NGC 7331. A mere 50 million light-years away, the large spiral is one of the brighter galaxies not included in Charles Messier's famous 18th century catalog. The disturbed looking group of galaxies at the lower left is well-known as Stephan's Quintet. About 300 million light-years distant, the quintet dramatically illustrates a multiple galaxy collision, its powerful, ongoing interactions posed for a brief cosmic snapshot. On the sky, the quintet and NGC 7331 are separated by about half a degree.

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[Ann]

NGC 7331 and four background galaxies, from top to bottom, NGC 7336, NGC 7335, NGC 7340 and NGC 7337 (a barred spiral galaxy). Photo: Vicent Peris.

---

NGC 7331 and four background galaxies, NGC 7335, NGC 7336, NGC 7337 and NGC 7340, are collectively called the Deer Lick Group. According to Wikipedia, the four background galaxies are sometimes called "the fleas".

Very interesting, at least to me, is that the "fleas" of the Deer Lick Group are at about the same distance from us as Stephan's Qiuntet, or 300 million light-years!

Stephan's Quintet with foreground galaxy NGC 7320. Photo: NASA, ESA, Hubble. Processing: Daniel Nobre.

---

But one of the galaxies that seems to belong to Stephan's Quintet, NGC 7320, is a foreground object. The Hubble picture at left clearly shows that one of the galaxies has a faint bulge, a tiny nucleus, and a knotty blue disk full of regions of star formation. Another Hubble image brings out the difference between NGC 7320 and the "real" Stephan's Quintet galaxies even more strongly.

Deer Lick Group and companion with arrow.png

A faint fuzzy companion galaxy of NGC 7331?

According to Wikipedia, NGC 7320 is only 39 million light-years away, making it a possible (but perhaps not probable) physical member of an extended NGC 7331 group of galaxies. NGC 7331 itself is believed to be a distance of 50 million light-years.

But if NGC 7320 is not a member of a physical NGC 7331 group, today's APOD is showing us just the sort of galaxy that probably is. I have marked it with an arrow in the picture at right.

Note how faint this galaxy is. Note its color. It's not yellow, so it doesn't contain a rich massive collection of small red stars. It's not blue, so it displays little or no star formation. To me, this galaxy looks very much like a faint fuzzy lenticular or spheroidal companion galaxy of NGC 7331.

Unfortunately, I can't find this galaxy with the help of my software Guide. Does anyone else know anything about this galaxy?

Ann

[Ann]

Annotated image of Stephan's Quintet. Photo: Putman Mountain Observatory.

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Stephan's Quintet (lower left), and NGC 7331 and parts of the Deer Lick Group (upper right) in ultraviolet light. Photo: GALEX/NASA/JPL-Caltech/SSC.

---

Can't resist showing you an annotated image of Stephan's Quintet, as well as an ultraviolet image of Stephan's Quintet, NGC 7331 and parts of the Deer Lick Group.

As you can see in the image at left, most of the action in Stephan's Quintet is happening because NGC 7318 A and NGC 7318 B are colliding with each other, throwing out monstrously long thick filaments of twisted gas and triggering huge amounts of star formation in the process. Nearby NGC 7319 has also been affected, and its spiral arms have been stretched and twisted due to tidal forces. A long curving tidal tail has also been thrown out of NGC 7319. It's interesting to see this tidal chaos in ultraviolet, isn't it? Also note the comparatively large, beautifully regular ellipsoid of blue (=ultraviolet) light from foreground galaxy NGC 7320.

In the Deer Lick Group, note the blue spiral arms of galaxy NGC 3773. Two of the "fleas" of the Deer Lick Group, NGC 7335 and NGC 7336, also show some signs of the presence of young ultraviolet stars. But the last galaxy is this group, NGC 7340, is not seen in this picture, because as a "moderate" (not giant) elliptical galaxy, it would almost certainly be all yellow at ultraviolet wavelengths (and therefore uninteresting at these short wavelengths).

NGC 7331 itself is seen to have a blue (=ultraviolet) spiral disk and a yellow bulge, as expected. (Even though its bulge isn't bulging very much, as you can see.)

The ultraviolet GALEX image can be seen at full size (1 MB) here.

Ann

[sillyworm 2]

NGC 7320 is a gorgeous galaxy.Is the bulge faint because of a low star count? Does the galaxy as a whole have a lower star count compared to others it's size?

[Ann]

NGC 7320 is a gorgeous galaxy.Is the bulge faint because of a low star count? Does the galaxy as a whole have a lower star count compared to others it's size?

You can actually tell at a glance that it is a small galaxy. And yes, its bulge is faint because it contains few stars.

NGC 7320. NASA/ESA/Hubble.

---

M61. Photo: Warren Keller.

---

The picture at right shows large Virgo Cluster spiral galaxy M61. You can tell at a glance that it is large. How? Well, look how detailed and well-defined the structures are, and how well separated the colors are. You can see that the galaxy has a bar, an inner ring, an yellow bulge or disk, and blue spiral arms. At least one of the arms is bright and well-defined.

Small galaxies just don't have that kind of elegant structural features and well separated colors.

Ann

[orin stepanek]

NGC7331eder_1024.jpg

I take it that The 5 bright spots above NGC 7331 are all galaxies!

[sillyworm 2]

Are smaller galaxies like NGC 7320 unusual perhaps because many of them have merged with other galaxies? Would the size of a galaxy be defined by prior merges? Was it just a matter of how much gas/ dust was available in one or another location?

[Chris Peterson]

Are smaller galaxies like NGC 7320 unusual perhaps because many of them have merged with other galaxies? Would the size of a galaxy be defined by prior merges? Was it just a matter of how much gas/ dust was available in one or another location?

There remain lots of unknowns when it comes to galaxy formation, but in most cases I think the size of the galaxy is defined by the latter. The amount of hydrogen available.

[sillyworm 2]

Thanks Chris.

[johnnydeep]

NGC 7320 is a gorgeous galaxy.Is the bulge faint because of a low star count? Does the galaxy as a whole have a lower star count compared to others it's size?

You can actually tell at a glance that it is a small galaxy. And yes, its bulge is faint because it contains few stars.

M61. Photo: Warren Keller.

---

Good stuff, but the link to M61 is broken for me. I get this error - is it just me?

403. That’s an error.

Your client does not have permission to get URL /proxy/KvOQBNIUiM8cKB8nvgz6Iq9Tx_synjhoc_IvGm4cn4Z8OsqR3OgrtZ82e8PSNPiPcSiP8ptw2sNl2xvZWGfX1X0eCtn9PdhNK3H__nJfgDEim_T28Vu4X8ObRa5mBJCR5WBi1vM from this server. (Client IP address: 24.184.25.213)

[Ann]

NGC 7320 is a gorgeous galaxy.Is the bulge faint because of a low star count? Does the galaxy as a whole have a lower star count compared to others it's size?

You can actually tell at a glance that it is a small galaxy. And yes, its bulge is faint because it contains few stars.

M61. Photo: Warren Keller.

---

Good stuff, but the link to M61 is broken for me. I get this error - is it just me?

403. That’s an error.

Your client does not have permission to get URL /proxy/KvOQBNIUiM8cKB8nvgz6Iq9Tx_synjhoc_IvGm4cn4Z8OsqR3OgrtZ82e8PSNPiPcSiP8ptw2sNl2xvZWGfX1X0eCtn9PdhNK3H__nJfgDEim_T28Vu4X8ObRa5mBJCR5WBi1vM from this server. (Client IP address: 24.184.25.213)

It works for me. You had problem with another galaxy picture that I posted, and that one too, worked for me.

M 61 Warren Keller.png

Is this better?

Ann

[johnnydeep]

You can actually tell at a glance that it is a small galaxy. And yes, its bulge is faint because it contains few stars.

M61. Photo: Warren Keller.

---

Good stuff, but the link to M61 is broken for me. I get this error - is it just me?

403. That’s an error.

Your client does not have permission to get URL /proxy/KvOQBNIUiM8cKB8nvgz6Iq9Tx_synjhoc_IvGm4cn4Z8OsqR3OgrtZ82e8PSNPiPcSiP8ptw2sNl2xvZWGfX1X0eCtn9PdhNK3H__nJfgDEim_T28Vu4X8ObRa5mBJCR5WBi1vM from this server. (Client IP address: 24.184.25.213)

It works for me. You had problem with another galaxy picture that I posted, and that one too, worked for me.

M 61 Warren Keller.png

Is this better?

Ann

Yes - that I see! (and thanks for remembering that similar broken link I posted about before )

Were the broken links on your google drive perchance? If so, I think they have to be explicitly "shared to all" or some such thing. I'd like to know if those links were broken for others besides me.

[MarkBour]

Were the broken links on your google drive perchance? If so, I think they have to be explicitly "shared to all" or some such thing. I'd like to know if those links were broken for others besides me.

I can follow the link:

https://lh3.googleusercontent.com/proxy ... JCR5WBi1vM

and it pulls up the lovely image of M61.

However, if I follow the link you had in one of your replies:

/proxy/KvOQBNIUiM8cKB8nvgz6Iq9Tx_synjhoc_IvGm4cn4Z8OsqR3OgrtZ82e8PSNPiPcSiP8ptw2sNl2xvZWGfX1X0eCtn9PdhNK3H__nJfgDEim_T28Vu4X8ObRa5mBJCR5WBi1vM

with the IP address you listed (24.184.25.213) in place of the domain, I get no response. Try the full URL:

https://
lh3.googleusercontent.com/proxy/KvOQBNIUiM8cKB8nvgz6Iq9Tx_synjhoc_
IvGm4cn4Z8OsqR3OgrtZ82e8PSNPiPcSiP8ptw2sNl2xvZWGfX1X0eCtn9PdhNK3H__
nJfgDEim_T28Vu4X8ObRa5mBJCR5WBi1vM

in your browser and see if it gives the image or the error. (I broke it apart so APOD would stop messing up the display of it and would plot every character. But you'll have to remove the 3 bits of whitespace -- after the "//", the "_", and the "__" -- to try it by hand.)

By the way, the IP you were hitting (24.184.25.213) geo-locates to Long Island in New York, though I doubt that info helps.

[MarkBour]

NGC7331eder_1024.jpg


I take it that The 5 bright spots above NGC 7331 are all galaxies!

Orin --

The first image Ann posted in this thread shows those 5 spots in more detail, plus another fainter one just to the right of those 5. (It's to the right in the orientation of the APOD image, it's above them in the orientation of Ann's image.) It appears that 3 of your 5 bright spots are galaxies and two of them (the upper right 2) are foreground stars. As Ann mentioned, the spots that are galaxies (referred to as "the fleas") are all much farther away than NGC 7331, the Deer Lick itself.

[MarkBour]

Capture1.PNG

Deer Lick Group and companion with arrow.png
A faint fuzzy companion galaxy of NGC 7331?

According to Wikipedia, NGC 7320 is only 39 million light-years away, making it a possible (but perhaps not probable) physical member of an extended NGC 7331 group of galaxies. NGC 7331 itself is believed to be a distance of 50 million light-years.

But if NGC 7320 is not a member of a physical NGC 7331 group, today's APOD is showing us just the sort of galaxy that probably is. I have marked it with an arrow in the picture at right.

Note how faint this galaxy is. Note its color. It's not yellow, so it doesn't contain a rich massive collection of small red stars. It's not blue, so it displays little or no star formation. To me, this galaxy looks very much like a faint fuzzy lenticular or spheroidal companion galaxy of NGC 7331.

Unfortunately, I can't find this galaxy with the help of my software Guide. Does anyone else know anything about this galaxy?

Ann

Ann, I'm sure you're more adept with SIMBAD than I am, but I tried looking this up. I went to NGC 7331, zoomed in on the region, scrolled to your faint spot, copied the coordinates (22 37 12.474 +34 37 11.70) into a SIMBAD coordinate query, and got the following results:

Capture.png

The top entry is LEDA 2051985. There's mention of it on Stargazer's Lounge: https://stargazerslounge.com/topic/3620 ... -qunittet/ and a paper they refer at: https://arxiv.org/ftp/arxiv/papers/1701/1701.00615.pdf .

Is that your target?

[johnnydeep]

Were the broken links on your google drive perchance? If so, I think they have to be explicitly "shared to all" or some such thing. I'd like to know if those links were broken for others besides me.

I can follow the link:

https://lh3.googleusercontent.com/proxy ... JCR5WBi1vM

and it pulls up the lovely image of M61.

However, if I follow the link you had in one of your replies:

/proxy/KvOQBNIUiM8cKB8nvgz6Iq9Tx_synjhoc_IvGm4cn4Z8OsqR3OgrtZ82e8PSNPiPcSiP8ptw2sNl2xvZWGfX1X0eCtn9PdhNK3H__nJfgDEim_T28Vu4X8ObRa5mBJCR5WBi1vM

with the IP address you listed (24.184.25.213) in place of the domain, I get no response. Try the full URL:

https://
lh3.googleusercontent.com/proxy/KvOQBNIUiM8cKB8nvgz6Iq9Tx_synjhoc_
IvGm4cn4Z8OsqR3OgrtZ82e8PSNPiPcSiP8ptw2sNl2xvZWGfX1X0eCtn9PdhNK3H__
nJfgDEim_T28Vu4X8ObRa5mBJCR5WBi1vM

in your browser and see if it gives the image or the error. (I broke it apart so APOD would stop messing up the display of it and would plot every character. But you'll have to remove the 3 bits of whitespace -- after the "//", the "_", and the "__" -- to try it by hand.)

By the way, the IP you were hitting (24.184.25.213) geo-locates to Long Island in New York, though I doubt that info helps.

Thanks for your testing. None of your links work for me. I am indeed living on Long Island. I wonder if I have to clear my router cache or something like that. Aha, I get the same error both from my iPad and from my Dell laptop, including the same IP, which must mean that that IP is actually the router address...I think.

[johnnydeep]

Capture1.PNG
Deer Lick Group and companion with arrow.png
A faint fuzzy companion galaxy of NGC 7331?

According to Wikipedia, NGC 7320 is only 39 million light-years away, making it a possible (but perhaps not probable) physical member of an extended NGC 7331 group of galaxies. NGC 7331 itself is believed to be a distance of 50 million light-years.

But if NGC 7320 is not a member of a physical NGC 7331 group, today's APOD is showing us just the sort of galaxy that probably is. I have marked it with an arrow in the picture at right.

Note how faint this galaxy is. Note its color. It's not yellow, so it doesn't contain a rich massive collection of small red stars. It's not blue, so it displays little or no star formation. To me, this galaxy looks very much like a faint fuzzy lenticular or spheroidal companion galaxy of NGC 7331.

Unfortunately, I can't find this galaxy with the help of my software Guide. Does anyone else know anything about this galaxy?

Ann

Ann, I'm sure you're more adept with SIMBAD than I am, but I tried looking this up. I went to NGC 7331, zoomed in on the region, scrolled to your faint spot, copied the coordinates (22 37 12.474 +34 37 11.70) into a SIMBAD coordinate query, and got the following results:

Capture.png

The top entry is LEDA 2051985. There's mention of it on Stargazer's Lounge: https://stargazerslounge.com/topic/3620 ... -qunittet/ and a paper they refer at: https://arxiv.org/ftp/arxiv/papers/1701/1701.00615.pdf .

Is that your target?

Nice sleuthing! It’s certainly “dwarf M” in that PDF paper.

[MarkBour]

Thanks for your testing. None of your links work for me. I am indeed living on Long Island. I wonder if I have to clear my router cache or something like that. Aha, I get the same error both from my iPad and from my Dell laptop, including the same IP, which must mean that that IP is actually the router address...I think.

Wow. I wonder what might be causing this. I mean if you have a router that's turning that link into a location that's not really out in the cloud, that sounds vaguely possible. It quickly gets over my head when networking or IP discussions get off of the most basic level. If you have an Internet Service Provider, they might be able to diagnose. If you're your own provider, you must be way beyond me in ability to diagnose. I do hope you can clear it up.

I'm guessing you can see not only the APOD itself, but also images folks upload to the Starship Asterisk discussion board. But that one image of Ann's was an external link she posted. So, I guess as far as we know, it's just a problem getting to that one URL domain, or maybe the router next to Ann's image is blocking connections from New York. Probably scared of COVID .

[Ann]

Capture1.PNG
Deer Lick Group and companion with arrow.png
A faint fuzzy companion galaxy of NGC 7331?

According to Wikipedia, NGC 7320 is only 39 million light-years away, making it a possible (but perhaps not probable) physical member of an extended NGC 7331 group of galaxies. NGC 7331 itself is believed to be a distance of 50 million light-years.

But if NGC 7320 is not a member of a physical NGC 7331 group, today's APOD is showing us just the sort of galaxy that probably is. I have marked it with an arrow in the picture at right.

Note how faint this galaxy is. Note its color. It's not yellow, so it doesn't contain a rich massive collection of small red stars. It's not blue, so it displays little or no star formation. To me, this galaxy looks very much like a faint fuzzy lenticular or spheroidal companion galaxy of NGC 7331.

Unfortunately, I can't find this galaxy with the help of my software Guide. Does anyone else know anything about this galaxy?

Ann

Ann, I'm sure you're more adept with SIMBAD than I am, but I tried looking this up. I went to NGC 7331, zoomed in on the region, scrolled to your faint spot, copied the coordinates (22 37 12.474 +34 37 11.70) into a SIMBAD coordinate query, and got the following results:

Capture.png

The top entry is LEDA 2051985. There's mention of it on Stargazer's Lounge: https://stargazerslounge.com/topic/3620 ... -qunittet/ and a paper they refer at: https://arxiv.org/ftp/arxiv/papers/1701/1701.00615.pdf .

Is that your target?

Thanks, Mark, it is indeed! (And I'm awful at SIMBAD, so I'm likely to ask for your help in the future, too.)

And thanks for the links, too, especially for the link to the arXiv paper!

Thanks again!

Ann

[orin stepanek]

NGC7331eder_1024.jpg


I take it that The 5 bright spots above NGC 7331 are all galaxies!

Orin --

The first image Ann posted in this thread shows those 5 spots in more detail, plus another fainter one just to the right of those 5. (It's to the right in the orientation of the APOD image, it's above them in the orientation of Ann's image.) It appears that 3 of your 5 bright spots are galaxies and two of them (the upper right 2) are foreground stars. As Ann mentioned, the spots that are galaxies (referred to as "the fleas") are all much farther away than NGC 7331, the Deer Lick itself.

Thanks Mark; looks like they maybe they are forghound stars!

[Ann]

Were the broken links on your google drive perchance? If so, I think they have to be explicitly "shared to all" or some such thing. I'd like to know if those links were broken for others besides me.

I can follow the link:

https://lh3.googleusercontent.com/proxy ... JCR5WBi1vM

and it pulls up the lovely image of M61.

However, if I follow the link you had in one of your replies:

/proxy/KvOQBNIUiM8cKB8nvgz6Iq9Tx_synjhoc_IvGm4cn4Z8OsqR3OgrtZ82e8PSNPiPcSiP8ptw2sNl2xvZWGfX1X0eCtn9PdhNK3H__nJfgDEim_T28Vu4X8ObRa5mBJCR5WBi1vM

with the IP address you listed (24.184.25.213) in place of the domain, I get no response. Try the full URL:

https://
lh3.googleusercontent.com/proxy/KvOQBNIUiM8cKB8nvgz6Iq9Tx_synjhoc_
IvGm4cn4Z8OsqR3OgrtZ82e8PSNPiPcSiP8ptw2sNl2xvZWGfX1X0eCtn9PdhNK3H__
nJfgDEim_T28Vu4X8ObRa5mBJCR5WBi1vM

in your browser and see if it gives the image or the error. (I broke it apart so APOD would stop messing up the display of it and would plot every character. But you'll have to remove the 3 bits of whitespace -- after the "//", the "_", and the "__" -- to try it by hand.)

By the way, the IP you were hitting (24.184.25.213) geo-locates to Long Island in New York, though I doubt that info helps.

Now the link to the photo of M61 doesn't work for me either. So it's a good thing that I uploaded the picture to my computer and posted it as an attachment.

Ann

[MarkBour]

Now the link to the photo of M61 doesn't work for me either. So it's a good thing that I uploaded the picture to my computer and posted it as an attachment.

Ann

Vanished for me, too. But the copy in your "Is this better" note is still visible.