Starship Asterisk*

NGC 7814: The Little Sombrero in Pegasus

Explanation: Point your telescope toward the high flying constellation Pegasus and you can find this expanse of Milky Way stars and distant galaxies. Centered on NGC 7814, the pretty field of view would almost be covered by a full moon. NGC 7814 is sometimes called the Little Sombrero for its resemblance to the brighter more famous M104, the Sombrero Galaxy. Both Sombrero and Little Sombrero are spiral galaxies seen edge-on, and both have extensive central bulges cut by a thinner disk with dust lanes in silhouette. In fact, NGC 7814 is some 40 million light-years away and an estimated 60,000 light-years across. That actually makes the Little Sombrero about the same physical size as its better known namesake, appearing to be smaller and fainter only because it is farther away. A very faint dwarf galaxy, potentially a satellite of NGC 7814, is revealed in the deep exposure just below the Little Sombrero.

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There is another, similar faint smudge to the one mentioned at 8 o'clock two diameters out.

Oh, that's a very nice picture!

I'll come back with more comments when I can use my software to say something meaningful about this galaxy!

Ann

tlc2357 wrote:There is another, similar faint smudge to the one mentioned at 8 o'clock two diameters out.

Darn, I've been ninja'd.

Nice! Kind of a Sumbrero Jr>

orin stepanek wrote:
Nice!

Kind of a Sumbrero Jr>

Shade + UMBRa => SUMBRero

I know it is apparently surrounded by objects....but it looks kind of "lonely"....

:---[===] *

Beautiful deep space images like this always fascinate me for much more that just the main subject galaxy, because in addition to the main attraction there are always a host of distant galaxies and groups of galaxies in the background. I found two groupings to be of particular interest here.

The first is located near the top edge at about 11 o’clock from the Little Sombrero. It is a group of three galaxies that are clearly in a merger dance, since tidal tails are very noticeable here. It makes me think of what our local group might look like after the big three have close encounters in several billion years.

The second grouping that caught my eye is a ruddy little group not far (in the photo) to the left of the main subject. There’s a brighter galaxy in the center with a small swarm of lesser satellite galaxies all around it, but all of these galaxies have a similar reddish appearance. Since the distant galaxies in this area are all reddened to about the same degree I would suspect that we might be seeing them through a patch of dust (inside our galaxy?).

The Little Sombrero itself can’t be left out, for it is spectacular. Its central bulge is much more prominent than that of the last edge on spiral which our ship recently visited. http://asterisk.apod.com/viewtopic.php?f=9&t=32291

To avoid rekindling argument I will refrain at this time from saying what the Little Sombrero’s bulge reminds me of.

BDanielMayfield wrote:... I found two groupings to be of particular interest here.

The first is located near the top edge at about 11 o’clock from the Little Sombrero. It is a group of three galaxies that are clearly in a merger dance, since tidal tails are very noticeable here. It makes me think of what our local group might look like after the big three have close encounters in several billion years.

I was going to mention that little group. Here's a crop of them, from the available larger image. I suspect that the yellow third member might be much farther away, but the top two are certainly engaged in a dance.
Rob

Then there's this orange/blue pair, from down along the right edge of the picture, which Ann may be delighted to see. They're likely only coincidently aligned, but they certainly enhance each other's colours.
Rob

rstevenson wrote:

BDanielMayfield wrote:The first is located near the top edge at about 11 o’clock from the Little Sombrero. It is a group of three galaxies that are clearly in a merger dance, since tidal tails are very noticeable here. It makes me think of what our local group might look like after the big three have close encounters in several billion years.

I was going to mention that little group. Here's a crop of them, from the available larger image. I suspect that the yellow third member might be much farther away, but the top two are certainly engaged in a dance.

butterfly group.jpg

Rob

There they be. Thanks Rob. What makes me think that the lower “yellow third member” is also involved is that we can see a dim tidal tail extending underneath it. But you certainly could be right about it being in the background.

That organge and blue galaxy pair are striking quite a pose too.

Even though I am happy that I was able to capture the deep field around NGC7814 I wish that I could use a larger instrument to bring out more detail in some of the interesting interacting groups. This image was taken for the star stream survey and the goal was to go deep enough to capture the faint dwarf below NGC7814. As mentioned there is another one at the 8:00 O.C. position. I normally would not share a "raw" data frame but I though you might find it interesting to see a Luminance (Clear Filter B&W) image that has been brightened to the point of noise to reveal more of the very faint background galaxies. This image is at 1/2 resolution.

Kindest Regards,
Ken Crawford
http://www.imagingdeepsky.com

Thanks for that, Ken.

I don't mind the noise at all. This is an entirely subjective statement I am about to make but when noise is present it feels more realistic to me. Smoothing everything out and making it like a model's skin on the cover of a fashion magazine...well, I know she's got wrinkles just like me. Doesn't matter that they hid them from me.

Ken Crawford wrote:Even though I am happy that I was able to capture the deep field around NGC7814 I wish that I could use a larger instrument to bring out more detail in some of the interesting interacting groups. This image was taken for the star stream survey and the goal was to go deep enough to capture the faint dwarf below NGC7814. As mentioned there is another one at the 8:00 O.C. position. I normally would not share a "raw" data frame but I though you might find it interesting to see a Luminance (Clear Filter B&W) image that has been brightened to the point of noise to reveal more of the very faint background galaxies. This image is at 1/2 resolution.

Kindest Regards,
Ken Crawford
http://www.imagingdeepsky.com

Using a larger telescope for more detail would be great but it would come at expense of a smaller field of view, which would omit many interesting background galaxies such as the interacting trio at top.

Maybe we could all chip in and buy a few hours on Hubble to give us a close-up look at some of those bits and pieces -- including those possible small companions to the Little Sombrero.

Maybe we could all chip in and buy Hubble when NASA doesn't want it any more.

Rob

Ken Crawford wrote:Even though I am happy that I was able to capture the deep field around NGC7814 I wish that I could use a larger instrument to bring out more detail in some of the interesting interacting groups. This image was taken for the star stream survey and the goal was to go deep enough to capture the faint dwarf below NGC7814. As mentioned there is another one at the 8:00 O.C. position. I normally would not share a "raw" data frame but I though you might find it interesting to see a Luminance (Clear Filter B&W) image that has been brightened to the point of noise to reveal more of the very faint background galaxies. This image is at 1/2 resolution.

Kindest Regards,
Ken Crawford
http://www.imagingdeepsky.com

Ken, thanks for the main image and for sharing the black and white one too. On the black and white there is another possible satellite of NGC 7814 that stands out better here than in the color image. It is centered at about pixel coordinates 543, 578.

That's an interesting one. I took the large B&W image and manipulated the contrast and brightness to see what that third blob looks like. Unlike the two blobs below the main galaxy, this one picks up some structure. That may mean it's a distant galaxy rather than a companion, or it may mean I'm imagining things. After all, given sufficient manipulation I could probably turn it into a picture of a US penny. At any rate, here's that third blob, enhanced.
Rob

Anyone really interested in those dim blobs should definitely check out Frontier Fields. They're actually going to reconstruct the galaxies to what they would appear like if they were not gravitationally lensed. To increase accuracy, multiple teams will independently reconstruct and then they will compare them. The less the variation, the more accurate the view. This puts our understanding of gravity to the test. Dark matter is still dark.

Wow, this thread has become so extremely interesting while I was away! Thanks to everyone who chipped in with observations and comments on background galaxies and dwarf galaxies!

Thanks in particular to Ken Crawford, for sharing your raw data frame with us, and to Rob, for your splendid pixellating talents and your great job bringing out background galaxies and companion galaxies. In my completely amateur opinion, the three galaxies that you brought out so beautifully for us here likely all belong to the same group and are locked in a common tidal embrace, just like BDanielMayfield suggested.

Oh, and Rob - I love that orange and blue pair, just like you thought I would!

On the other hand, I don't think I agree with you when you guessed that this galaxy may be a background object, considerably more distant than NGC 7814. The galaxy is faint and "soft", and it lacks the sharply defined central brightening that we would expect from a major galaxy. Therefore I believe it is a dwarf galaxy, although it may be larger than the other companions of NGC 7814. Note this galaxy's blue color, which is much bluer than the color of the dwarf galaxy directly "below" NGC 7814. This galaxy must have had some recent star formation. On the other hand, its star formation could have ceased by now, leaving behind a slowly dispersing and moderately but not very bright and blue population of A-type stars like Sirius and Vega. The structure of this galaxy, by the way, is similar to what the Large Magellanic Cloud would have looked like if its star formation had ceased after the formation of its bar. Fascinatingly, there is just a hint of of a polar ring around this galaxy. So if it is a polar ring galaxy, does that make it big? No, not necessarily. The polar ring galaxy I just linked to is less than half as bright as the Milky Way, according to my software. But that galaxy is much yellower and has a much more definite structure than the galaxy here.

Ann

BDanielMayfield wrote:

The second grouping that caught my eye is a ruddy little group not far (in the photo) to the left of the main subject. There’s a brighter galaxy in the center with a small swarm of lesser satellite galaxies all around it, but all of these galaxies have a similar reddish appearance. Since the distant galaxies in this area are all reddened to about the same degree I would suspect that we might be seeing them through a patch of dust (inside our galaxy?).

I'd say that these are definitely background galaxies. Note how very small they are, in addition to their redness. This kind of redness shared by a whole group of small-looking galaxies means that the galaxies have been reddened by the expansion of the universe, which has "stretched" the light they emitted to longer and redder wavelengths.

Note that one of the galaxies is bigger and brighter than the others. This could be a distant group of elliptical galaxies, and the brightest one could be really massive.

Ann

Okay, just one more. I just have to confirm that NGC 7814 really is very similar to M104. Both galaxies have very similar and quite red colors. They have huge bulges and halos and thin dust disks with little star formation. NGC 7814, interestingly, appears to have significant population of intermediately aged stars of spectral classes A, F and G in its disk. M104, by contrast, lacks any obvious concentrations of young stars.

M104 was recently described as two galaxies in one, a combination of an elliptical galaxy and a disk galaxy. Long ago, when the universe was much more gas-rich than today, gas clouds are believed to have fallen into orbit around the young M104, eventually giving rise to the flat disk that we see today. (Maybe M104 can be described as a galaxy-sized version of Saturn?)

Given that NGC 7814 is so similar to M104, it seems likely that the two galaxies formed in similar ways.

Ann

When I invert the image then adjust the brightness and contrast, the "Blob" at 8:00 appears to be located within a slight tidal stream pointing in the direction of the center of the little sombrero. The "Blob" at 6:00 might also share the same type of structure though fainter. The "Blob" at 10:00 still resembles a blob with no apparent tidal streaming

I assume those are Globular Clusters around, above and below the hub....appears to extend toward the ends as well...

:---[===] *

Ann wrote:

BDanielMayfield wrote:

The second grouping that caught my eye is a ruddy little group not far (in the photo) to the left of the main subject. There’s a brighter galaxy in the center with a small swarm of lesser satellite galaxies all around it, but all of these galaxies have a similar reddish appearance. Since the distant galaxies in this area are all reddened to about the same degree I would suspect that we might be seeing them through a patch of dust (inside our galaxy?).

I'd say that these are definitely background galaxies. Note how very small they are, in addition to their redness. This kind of redness shared by a whole group of small-looking galaxies means that the galaxies have been reddened by the expansion of the universe, which has "stretched" the light they emitted to longer and redder wavelengths.

Note that one of the galaxies is bigger and brighter than the others. This could be a distant group of elliptical galaxies, and the brightest one could be really massive.

Ann

I love this Ann! Your explanation for why this group looks red is Far OUT!

Bruce

Don’t know why my last comment was attributed to “Guest”, but it came from that weird sonofafarmer from south Texas normally known as BDanielMayfield. Wasn’t trying to be an ominous.