NGC7127

Sometimes I wonder why I research my objects. This is such a case. The more I looked the more confusing things became.

NGC 7127 is listed as an open cluster in northeastern Cygnus. I'd normally give a distance at this point but my research turned up nothing but confusion. I found only one reference, a Polish Wiki page, that gave a distance. They gave a distance of 4700 light-years. But when I checked the footnote for the distance that took me to a SEDS page on the cluster that never gave a distance! WEBDA, my usual go-to source for open clusters, had nothing on it but a position. But several of the stars were bright enough that parallax data from Hipparcos was available from The Sky's database. That gave distances to 4 apparent cluster members, two about 200 light-years and two of about 2000 light-years. These were the 4 most "obvious" cluster members. If right it would indicate this is not an open cluster at all but an asterism. So I went to the papers listed at SIMBAD. The first is for a galaxy NGC 7217! Yikes, the wrong object entirely. But I have taken this galaxy! The other references at least applied to open clusters.

One says it is a real open cluster with an age of 100,000,000 years and a distance of 5700 parsecs (18,500 light-years). So that means the 4 stars with Hipparcos data are foreground stars. http://cdsbib.u-strasbg.fr/cgi-bin/cdsbib?2012A%26A...542A..68P

The cluster/object looks to be in two parts one to the northwest and the other to the southeast. But this is seeing it projected in 2D. The 3D view may be quite different.

The cluster/object was discovered by John Herschel on September 25, 1829.

14" LX200R @ f/10, L=4x10' RGB=2x10', STL-11000XM, Paramount ME

Related Designations for NGC7127

NGC7128

NGC 7128 is an open cluster in the constellation of Cygnus. It is one of the prettier clusters in the original Herschel 400 list. The distance to it has usually been put at about 7500 light years but I found a well-researched paper indicating it is more like 13000 light years away give or take 10%. This puts it on the edge of the Perseus arm of our galaxy rather than between arms. Since it is a rather young cluster, something over 10 million years old, it wouldn't have had time to move out of an arm as the old distance estimates said. Another reason I like this new distance estimate.

I was drawn to this cluster by Dreyer's description which mentioned that it contained a ruby star. Always liking carbon stars and other very red stars I had to view it at the first opportunity. When I did I found it contained two bright orange stars and a third fainter one but I never did see the ruby star Dreyer mentions. Still, it is a great cluster visually due to the color contrast of those giant K stars standing in contrast to the blue A and B stars it contains.

It was discovered by William Herschel on October 14. 1787. My entry from the original H400 program using my 10" f/5 at up to 100x on a fair-but humid night on June 14, 1985 reads: "Small, round cluster circled three-quarters of the way around by bright stars. How could it be called "sparse" when it is such a small tight cluster. It's not condensed but isn't sparse!" By now if you've been reading through my site you are seeing a lot of May 1985 and later entries all saying humid. This is because I was working from my old cabin on the lake. I had to set up right along the shore. Down there it is always very humid. My observatory is on a very different part of the lake, atop a hill with the telescope over 60 feet above the lake and about 130 feet back from it. While it can be humid here as well It doesn't have the water vapor that rises from the lake giving near 100% humidity and ground fog. I'm now usually above that now.

Clusters need the very best nights for seeing as otherwise the stars just look lousy. I hate to "waste" a good night of seeing on just stars but when it's one of your favorite visual clusters you do so. Though I cheated and only used one 10 minute shot for each color channel. When there are no faint fuzzies you can get away with that. Oddly when I put it together the color was so strong I had to turn it down. Usually, I have to boost the color, especially of clusters. Not this time. I don't know why this turned out so differently as I didn't process it any differently.

Sorry, no faint fuzzies in the background. Just too much dust and gas in ours to let me see anything beyond. The image was taken September 17, 2009. I'm not gaining on my backlog.

14" LX200R @ f/10, L=4x10' RGB=1x10'x3, STL-11000XM, Paramount ME

Related Designations for NGC7128

NGC7132

NGC 7132 is a somewhat disturbed appearing spiral about 50 minutes of arc northeast of Enif, the nose of Pegasus. Redshift puts it 360 million light-years distant while a lone Tully-Fisher measurement says 270 million light-years. As the spiral structure appears rather disturbed and hard to measure rotation curves when seen this face on I'm going to go with the cosmological redshift distance of 360 million light-years. That would make it about 90,000 light-years in diameter. NED makes no attempt to classify it. The NGC project says Sc while Seligman says Sc? likely due to its disturbed appearance. It was discovered by Lewis Swift on October 18, 1884.

The galaxy has two main arms that appear rather normal though the one to the west does split into two. In the southern part of the galaxy, a dark cloud cuts horizontally across the galaxy and has a bright horizontal region above it. The bright region has a diagonal dark cloud set its left side off from the spiral arm it would otherwise cross. On the other side, it seems to pick up again only fainter but then curves north toward the outer edge of the galaxy while the dark cloud below it ends abruptly. M63 has a similar dark cloud that is thought to have been caused by dust left behind by a dwarf it is digesting the remains of which may be to the west side of M63 as a squiggle of a galaxy. In the case of NGC 7132, I don't see any remains though other parts of the galaxy's bright regions don't seem to conform to the structure of the two main arms as if the galaxy may be composed of two merging systems. Unfortunately, I can't find any papers discussing why it looks as it does much less supporting my hypothesis.

Only one other galaxy has redshift data at NED, it's the red spiral or S0 galaxy to the south, CGCG 427-023 which has a redshift similar to that of NGC 7132. Thus they are likely companions but it shows no distortions so I doubt it could be interacting with NGC 7132. I measure its size at a bit under 80,000 light-years. Assuming they are at the same distance then their separation is only 690,000 light-years.

With only two galaxies to annotate I wasn't going to prepare an annotated image but then three quasars, all quite distant at about 11 billion light-years did change my mind as they would be impossible to point out otherwise. A fourth at a similar redshift is just out of the field to the south.

A couple other galaxies are obvious in the field beside the usual faint background fuzzies. I've labeled them as well but with no redshift, I used a question mark for that field.

14" LX200R @ f/10, L=4x10' RGB=2x10' STL-11000XM, Paramount ME

Related Designations for NGC7132

NGC7137

NGC 7137 is a spiral galaxy in western Pegasus about 11 degrees north of M15. Redshift puts it 62 million light-years distant. A single Tully-Fisher estimate from 1988 puts it 82 million light-years away but has large error bars. It is classified as SAB(rs)c at NED while the NGC project just says S... whatever that means. Seligman says SBc? so there seems a slight difference of opinion about it. I'm not sure I even see it as barred. It is surrounded by a large faint, reddish halo of stars all papers seem to ignore that I saw. Using the redshift distance and including the halo, it is a bit over 40,000 light-years across. Some papers have said only 10 or 15 thousand. I don't know where they get that. Even if I use just the bright spiral section it is 18,000 light-years across by my measurement.

Being located in eastern Pegasus it isn't all that surprising to find some IFN in the image as I've found it in other images I've taken in this part of the sky. The brightest portion is to the northwestern corner of the image though fainter pieces are scattered elsewhere, mostly to the north. The galaxy was discovered by William Herschel on November 17, 1784, but didn't make either of the Herschel 400 observing programs for some reason. It certainly is bright enough at 13.0 magnitude and is very compact for a high surface brightness. Though it would be a challenge in an 8" scope. I've never looked for it visually which I find surprising.

NGC 7137 made it to my to-do list as a three-armed spiral according to a paper I saw. I looked at it in the POSS images and agreed. Since Arp had a category for 3 armed spirals but didn't include it I had to put it on the list. I never expected what I got. It has three arms, sort of, but each is very different. The one on the east is most typical but comes off of the core on a short side. That is, the core is oval east-west and it comes from above the north side of the core. If there's a bar it must run mostly east-west. The arm, however, is rather mottled with several star clusters. The arm on the west is shorter and comes from well below the south side of the core. In fact, the third arm starts between it and the core. The second arm, like the first, has hints of star clouds. The third arm however quickly breaks up into many star clouds, more than a dozen in fact. One paper came sort of close to describing what I saw when it says: "The disk is filled with arms which on one side break into six separate fragments; in contrast, there is but one major arm on the opposite side." I can't quite square that, especially the 6 fragments as I see over 12. This is one strange galaxy, even for a three-armed one. Stranger than the three he put into his atlas. But he worked from the POSS plates in many cases and those didn't begin to show how odd this one is. They make it look pretty typical and totally miss the large somewhat red halo around this blue galaxy. The bright portion is somewhat off center to the western side of the halo. I wonder if that indicates this odd structure of a flocculent galaxy with two rather normal arms is due to a merger in the recent past. Nothing I saw in any paper even hinted at this.

The blue galaxy 10 minutes nearly due west of NGC 7137 is UGC 11813, it is listed as being an Im: galaxy with a redshift distance of 69 million light-years so likely part of the group that NGC 7137 belongs to. No other galaxy in the image has redshift data so I didn't bother to prepare an annotated image.

This is my last August 2015 image. I'm finally moving to September images. I'm now only 3.5 months behind. I was 18 months behind a couple years ago. I'm catching up thanks to rotten imaging weather the last two years.

14" LX200R @ f/10, L=4x10' RGB=2x10', STL-11000XM, Paramount ME

Related Designations for NGC7137

NGC7139

NGC 7139 is a planetary nebula in Cepheus, about 4000 light years away. Keep in mind that the distances to such nebula are quite uncertain. There are several different methods of estimating the distance to planetary nebulae and they rarely agree. It was discovered by William Herschel on November 5, 1787. It is in the second H400 program.

This planetary is a red ring around a blue center. In this case, we find the red light is from NII, singly ionized nitrogen (unionized nitrogen is NI). This glows with almost the same red color as HII (there is only about a 3 angstrom difference for those who are interested). So most HII filters, including mine, pass both making it hard to tell if you are seeing HII or NII. In many cases of planetary nebulae, it is NII that gives the red color. This is true of some very major planetary nebula like M27 as well. In this case the central star is rather old and has cooled to white-hot status and isn't all that blue in color. This lowers the amount of ultraviolet radiation. Close to the star, there is enough to cause OIII to glow with its characteristic blue color but that fades as you reach the outer parts of the nebula and there is no longer enough to cause oxygen to be doubly ionized. Nor is there enough to singly ionize Nitrogen without help. It turns out the star, when alive, had a strong solar wind that blew a hole in the interstellar medium. This is quite common, our sun is doing the same but to a lesser extent. That will change as our sun ages and its solar wind gets stronger. When the star "died" and sent off its outer shell through space it expanded unhindered by the interstellar gases thanks to this bubble, but it has now run into the edge of the bubble. Gases pile up creating a shock front. Energy from this and what reaches it from the central star are enough to cause the nitrogen to singly ionize with its characteristic red color. But it isn't sufficient to doubly ionize oxygen so we don't see the blue which would normally overwhelm NII emissions so the red NII emission defines the shock front where it meets the interstellar medium. While it likely is doing this in a full bubble we only see the red along the edges of the bubble where we see the most gas due to looking through the edges of the bubble. Though there is some evidence that gas is thrown off mostly from the equator of the star so it could be we are looking at this star right down its north or south pole and this is the edge of a disk or cylinder of material the star threw off. In other words, there is a lot about these nebulae we still don't understand! The blue parts of the nebula look washed out blue because there is a lot of HII emission mixed in with the OIII. Not enough to turn it red but enough to wash out the blue color, especially into blobs on either side of the central star.

14" LX200R @ f/10, L=4x10' RGB=1x10x3, STL-11000XM, Paramount ME

Related Designations for NGC7139

NGC7142

NGC 7142 is an open cluster in Cepheus that was discovered by William Herschel on October 18, 1794. It' isn't in either H400 program, WEBDA puts it at a distance of 5,500 light-years. The cluster is in the original Herschel 400 Observing Program. My entry from June 14, 1985, with my trusty Cave 10" f/5 under humidity cloaked skies at 60x reads: "Large, highly elongated cluster of mostly very faint stars. Over 50 stars seen though all but a dozen seem too faint for a 6" telescope, at least under my humid skies. I ran right over this faint cluster the first time I looked for it. It must be very difficult in a 6" telescope." Odd but I had a 6" f/4 at hand but never used it on the cluster, only surmised what I'd see in it. Can't find I ever looked for it in either of my 6" scopes (f/4 or f/12). WEBDA puts the age of the cluster at 1.9 million years with 0.4 magnitudes of reddening from galactic dust.

I found this one on the hard drive and can't find I ever ran it before. Probably because it is one of the first color images I took digitally taken using a beginner's poor technique. The result isn't very good even with a lot of reprocessing to try and save it. Another for the reshoot list as it is very photon starved with only 25 rather than my usual 40 to 50 minutes of luminance data using 5 minute rather than 10 minute subs increasing decreasing the signal to noise ratio due to read noise not being swamped by photon noise.

14" LX200R @ f/10, L=5x5' RGB=3x5', STL-11000XM, Paramount ME

Related Designations for NGC7142

NGC7146

NGC 7146 and 7147 are the largest of the three galaxies in the WBL 672 galaxy group about 400 million light-years from us in southwestern Pegasus. Both appear to be red and dead spirals. Spirals that aren't making new stars in any significant amounts so all the hot blue stars that normally define spiral arms are long gone. Both are barred galaxies. Both were discovered on August 11, 1863 by Albert Marth being number 456 and 457 in his list.

The only blue galaxy in the group is CGCG 376-046. NED doesn't classify it, not even as a spiral which it obviously is. More confusing is that it is listed as a double galaxy. The brighter component is located about one galaxy diameter west of the blue galaxy. There's nothing at that location. The blue spiral they call CGCG 376-046 NED01 (I left the NED01 part off of the annotated image). The redshift for the missing galaxy gives a distance of 380 million light-years while the distance for the blue galaxy is listed at 280 million light-years. But then it notes another measurement that puts it about 380 million light-years. So that's what I used for the annotated image as most seem to include it as part of the group anchored by NGC 7146 and 7147. Also, the position of the missing galaxy is given with an error bar of 150" radius or anywhere in a 5 minute diameter circle centered on the position. I'm totally confused by what or where this galaxy is unless it is NGC 7147.

This area of the sky is poorly studied for galaxies. These are the only ones in my image with redshift data. Since there is a short asteroid trail near the top of the image I did prepare an annotated image (see it for details on the asteroid) and gave designations for the few in the image that had designations that weren't just positional. There weren't many of those either.

This was taken on the best of several poor nights I attempted it so doesn't begin to go as deep as I'd wanted to go. In fact, I marked all of them as unprocessable but decided this one night's attempt was worth trying to salvage. I think NGC 7147 may have some faint halo stars well beyond the edge as defined by my image as I see hints of it in the FITS but it was so in the noise I didn't try to pull it out. This shows better when I combined all nights but seeing was so bad for all but this night it may just be an artifact of the seeing. The best seeing frames I left in the image shows a diameter of just over 100,000 light-years using the 380 million light-year distance. NGC 7146 is slightly larger at 110,000 light-years. The blue spiral is 64,000 light-years across if the same distance but if it is really 280 million light-years away then it is only 47,000 light-years in size.

14" LX200R @ f/10, L=4x10' RGB=2x10', STL-11000XM, Paramount ME

Related Designations for NGC7146

NGC7156

NGC 7156 is a face on SAB(rs)cd: spiral in southeastern Pegasus. It is about 72 to 170 million light-years distant. OK, most sources say the distance is unknown. NED, however, puts the redshift distance at more than twice the Tully-Fisher determination. That makes it either 33.5 or 79.1 thousand light-years across. If I had to vote I'd say the redshift distance is likely closer to correct but that's just a guess.

It is a very lonely galaxy. It is considered an isolated galaxy. What attracted me to it was the odd broken arm south of the core. It just suddenly stops then restarts after a 9" gap. Is this really a gap or is a dust cloud blocking that part of the galaxy? I suspect it really has the gap we see. The other reason it was on my list is I'm slowly imaging the Herschel 400 objects I can reach from my 47 north latitude. This one is in the second 400 list. William Herschel discovered it on October 13, 1827. It is in the second H400 program. The NGC describes it as "faint, pretty large, round, brighter middle, mottled but not resolved".

Being isolated there's little on the field. While you will see a couple dozen obvious galaxies none had redshift data at NED. Only two quasars and some 22nd magnitude galaxies had any data. On a good night I could have picked up those 22nd magnitude galaxies but this was a poor night for transparency and the moon was brightening up the sky a bit which didn't help. I took 60 minutes of luminance data rather than my usual 40 but it didn't overcome the bad night and moon. The night really went bad when taking the green data which I saved for last since I can make a reasonable color image without it. One of the two frames was usable though noisy. I made it work.

Due to conditions, only one galaxy was bright enough for me to try and label though you will likely need to blow up the image to find it. It is label GP for galaxy pair which is NED's designation. For morphology they say Merger. So apparently it is two merging galaxies but at nearly 5.5 billion light-years I can't see much but a very faint smudge. The two quasars are also very distant but being quasars were bright enough I could pick them up even though one is nearly 12 billion light-years distant by light-travel time and the other not much closer, at a bit over 11 billion light-years. If not for them I'd not have prepared an annotated image as there wasn't even an asteroid down to 24th magnitude in the field let alone one bright enough to get through my gunky skies.

14" LX200R @ f/10, L=6x10' RB=2x10' G=1x10', STL-11000XM, Paramount ME

Related Designations for NGC7156

NGC7171

NGC 7171 is in southern Aquarius almost on the border with Capricornus. It is also very near the ecliptic so I expected some asteroids. Thanks to the smoke at -13 degrees only 3 of them are visible in the image. The smoke did help seeing some but dimmed the image by over a magnitude. Note how the three trails I did catch vary due to the smoke and how faint they are. Normally 19th magnitude asteroids are a lot brighter than these.

The smoke also resulted in a rather underexposed image with lots of noise. I needed considerably more exposure time to smooth things out. Still, it came out better than I would have expected due to conditions. This is the next to the last image I took with heavy smoke. Unfortunately, while the smoke is finally history the clouds aren't. It's been mostly cloudy since the smoke cleared. I've only managed two images in decent skies and they were taken the same night.

NGC 7171 was discovered by William Herschel on August 12, 1787, and is in the second H400 program. IC 1417 was discovered by Stephane Javelle on November 4, 1891. It is an Sb spiral by Seligman and Sb? sp Sy2 according to NED. NGC 7171 is SB(rs)b HII by NED and SBb? by Seligman. Seligman seems to like question marks.

Being at -13 degrees and not far from the Zone of Avoidance the field is poorly studied. I wanted to know more about LEDA 942584 but NED had little on it, not even a redshift. It looks interesting with its two well-defined arms. None of the other galaxies in the image but the NGC and IC galaxies have any info at NED. The only other object it has is what it says is a quasar right near IC 1417 by angular separation. The redshift for it is moot as to how it was determined but with only two significant digits for its redshift, I suspect it is photographic and may just be a field star. I included it as there was little else to annotate just note it may not be a quasar. Per NED 7 catalogs list it as a radio source and 5 list it as a quasar. It also has a few entries as an infrared source and an Xray source.

14" LX200R @ f/10, L=4x10' RGB=2x10', STL-11000XM, Paramount ME

Rick


http://www.mantrapskies.com//image-archive/NGC/NGC7171-IC1417/NGC7171L4X10RGB2X10.JPG
http://www.mantrapskies.com/image-archive/NGC/NGC7171-IC1417/NGC7171L4X10RGB2X10CROP125.JPG
http://www.mantrapskies.com/image-archive/NGC/NGC7171-IC1417/NGC7171L4X10RGB2X10ID.JPG

Related Designations for NGC7171

NGC7177

NGC 7177 is an SAB(r)b spiral in western Pegasus. Redshift puts it at 37 million light-years distant but its lack of resolution argues it is much more distant. The median of non-redshift measurements at NED put it at 79 million light-years which seems more reasonable. If the shorter distance is right it is only 32,000 light-years in diameter. That too seems wrong. The larger distance gives a size of 69,000 light-years which also is a better fit so I'm going with it being at least 79 million light-years distant.

The galaxy appears rather face on in some respects but the elongation east-west when the bar runs close to north-south doesn't seem to fit. Either it is oddly distorted or seen more edge on that its inner ring structure would indicate. That is rather odd as it is made up of mainly one bright arm coming from the end of the northern bar. The galaxy is rather red indicating new star formation is rare except for some slightly blue knots at the edge of the galaxy's disk.

NGC 7177 was discovered by William Herschel on October 15, 1784. It made my imaging list because of its odd inner arm structure and its inclusion in the Herschel 400 II observing list. It is another one I have not logged visually though I'm quite sure I've seen it back in the early 80's before I had a field computer to log in such observations for the second H400 project.

I wasn't going to prepare an annotated image as NGC 7177 is the only galaxy in the field with redshift data and there are no asteroids in the image. But then I saw IC 5153 was in the image. That is a very strange object in that it is far too faint to have been discovered by Guillaume Bigourdan with the 12" refractor he had available on September 30, 1891. When he recorded it he said it was "extremely faint, perhaps a star; 9.5 magnitude star 1.4 arcmin to southeast". According to my data, the galaxy is about magnitude 17.3 but the star just below it is magnitude 15.5. At 15.5 the star would just be at the limit of his scope. Thus it seems likely he just saw the star and got lucky that there is a galaxy next to it he couldn't have possibly seen. The 9.5 magnitude star is obvious to the lower left of the galaxy and star below it that he likely did see. NED says IC 5153 "includes the superposed star." Seligman considers it just the star. I put the label on the galaxy. This galaxy is near the top of my image right of NGC 7177.

14" LX200R @ f/10, L=4x10' RGB=2x10', STL-11000XM, Paramount ME

Related Designations for NGC7177