Interacting Galaxies
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Messier 51 - M51 is 35 million light-years away in Canes Venatici. A smaller companion galaxy, NGC 5195, seen to the left of M51 in this image, is partially obscured by the dust in one of M51's arms. The gravitational interaction of the two is evident from the gas and dust spewing from NGC 5195. It is believed that the prominent spiral arms in M51 are due to tidal forces from NGC 5195. There are many hot, young blue stars in the arms of M51 and well as reddish star-forming regions. In the distant future these two galaxies will merge.
Telescope: Meade 8" LX200R @ f/5 with 2" Antares 0.5X reducer Camera: SBIG ST-2000XM Exposures: L=90 min; R=G+B=30 min |
Messier 81 and Messier 82 - At the bottom of this image is M81, a spectacular spiral galaxy in Ursa Major about 12 million light-years from earth. It was discovered in 1774 by Johann Bode and is thus also known as Bode's Galaxy. Dust in the spiral arms is heated by young stars resulting in strong infrared emission. It is interacting gravitationally with M82, the galaxy at the top of this image, causing intense star formation in the latter. The star-forming region is just visible as red tendrils at the center of the galaxy. The overall result is that M82 is exceptionally bright, 5 times a bright as the whole Milky Way.
Telescope: Meade 14" LX200GPS @ f/2 with Hyperstar 3 Camera: SBIG ST-8300C Autoguiding: Orion ST-80 with Meade DSI using PHD Exposure: 65 minutes |
Arp 147(IC 298) - This is a pair of interacting ring galaxies about 450 million light-years away in Cetus. It is thought that this pair is a result of a cataclysmic collision during which the edge-on galaxy on the left passed through the center of the galaxy on the right, ripping out its core. The remnant of the latter galaxy is a ring of newly-formed, hot blue stars. The collision also created tidal streams of gas and stars around the galaxies. For size perspective the O-shaped galaxy is about 18 X 27 arc-sec, pretty near to lower limit for my equipment.
There are a number of more distant galaxies in the image, the most prominent being PGC 11893, the small blue spiral galaxy just below and to the left of IC 298. Telescope: Meade 14" LX200GPS @ f/7 with Starizona SCT corrector Camera: SBIG ST-8300C Autoguiding: Starlight Xpress OAG with Meade DSI using PHD2 Exposure: 12 X 30 minutes = 6hrs |
Arp 146 - This is a ring galaxy and its companion about 1 billion light-years away. The companion has apparently pierced the center of the ring ripping its nucleus out. According to L.D. Spight et al (1990) the ring is about 11 arcsec X 18 arcsec. They studied the structure of Arp 146 using CCD color photometry on the Mt. Bigelow 61” telescope. They identified four well-defined knots of starburst activity. From the color studies they found that the nucleus of the ring prior to the collision is imbedded in one of the knots. It has more older stars than the other knots. Also they found that the companion to the ring is in the foreground having passed through the ring from behind and that the northwest corner of the ring is tipped toward us.
Telescope: Meade 14" LX200GPS @ f/6.8 Camera: SBIG ST-8300C Autoguiding: Starlight Xpress OAG with Meade DSI using PHD2 Exposure: 14 X 30 minutes = 7 hrs |
Arp 299 - This pair of colliding galaxies in Ursa Major (IC 694 on the left and NGC 3690 on the right) were recently imaged by NASA’s X-ray imaging satellite, NuSTAR. The NuSTAR data show that a monster black hole in NGC 3690 is very actively devouring gas and dust, but the massive black hole in IC 694 seems to be either dormant or obscured by dust. This object is 130 million light years away and only measures about 2 arc minutes in size, making it difficult to image with a small telescope. The monster black hole is in the bright region near the center of the colliding galaxies. Above and to the left of Arp 299 is a distant barred spiral galaxy, PGC 35345, mag 15.7. The field of view of the above image is 7 arcmin X 9 arcmin. The NuStar and Hubble images can be see here - http://www.jpl.nasa.gov/news/news.php?feature=4435 .
Telescope: Meade 14" LX200GPS @ f/7 with Starizona SCT corrector Camera: SBIG ST-8300C Autoguiding: Starlight Xpress OAG with Meade DSI using PHD2 Exposure: 12 X 30 minutes = 6 hrs |
The Antennae Galaxies- These two galaxies, also designated as NGC 4038 (upper) and NGC 4039, are about 45 million light-years away in the constellation, Corvus. They are undergoing a collision and will eventually merge. The long talls of dust and gas are a result of their gravitational interactions and may indicate the paths they have taken as they have come together. Intense star formation is occurring in both. Another galaxy, NGC 4027, is visible in the lower right corner of the image. It is a barred spiral galaxy that has been distorted by a past collision with another galaxy.
Telescope: Meade 14" LX200GPS @ f/2 with Hyperstar 3 Camera: SBIG ST-8300C Autoguiding: Orion ST-80 with Meade DSI using PHD Exposure: 20 X 5 minutes = 1 hr 40 min |
The Leo Triplet - This trio of spiral galaxies in Leo consists of, clockwise from the top, NGC 3628, M65 and M66. The gravitational interactions among the three have resulted in the distortions seen in NGC 3628 and the faint outer arms of M66. The group is about 35 million light-years away.
Telescope: Meade 14" LX200GPS @ f/2 with Hyperstar 3 Camera: SBIG ST-8300C Autoguiding: Orion ST-80 with Meade DSI using PHD Exposure: 185 minutes |
NGC 2207 and IC 2163 - These are thought to be galaxies that have undergone a glancing collision with the smaller (IC 2163) passing behind the larger (NGC 2207). They are about 150 million light-years away in Canis Major. The gravitational interaction of the two has produced gas, dust and star streams that are faintly visible in this image.
Telescope: Meade 8" LX200R @ f/7 Camera: SBIG ST-2000XM Exposures: L=300 min; R=G=B=60 min |
Arp 272 and IC 1183 - Looking through Hubble images I found one that looked interesting. Arp 272 appeared to be a collision of 3 galaxies about 48 arcsec in size. Noticing that it is in the Hercules Galaxy Cluster (Abell 2151), I decided to see if it was discernible in the image I made of the cluster in 2009. Sure enough it was, so I reprocessed that image with an enlargement of Arp 272. There are 3 cores visible, but it is not known if the smaller core to the north of the two larger cores is a separate galaxy or a bright cluster of stars created by the collision. Arp 272 and the Hercules cluster are about 500 million light-years away.
As I was reprocessing my old image, I noticed an interesting looking feature near Arp 272 that looked a bit like a tadpole. A little research showed it to be IC 1182, designated a “peculiar” galaxy. The bright core has a faint tail extending to the west with several blue puffs. Also there is a very faint (you’ll have to squint) puff of gas to the north of the core that is not clearly associated with it. A Spanish-Italian-Danish group studied IC 1182 in 2004 and published their findings (see http://arxiv.org/pdf/astro-ph/0402219v1.pdf ). Their conjecture is that what we see is the result of an ongoing collision of 2 galaxies resulting in massive star formation and that there are two tidal streams emanating from the core, one to the west with the blue knots and another very faint one to the north. The blue knots in the westerly stream may be dwarf galaxies spawned by the collision. Total exposure was 6 hrs with SBIG ST2000XM camera on 8" Meade LX200R at f/7 (1400 mm fl) |
NGC 3169, 3166 and 3165 - These interacting galaxies in Sextans are about 60 million light-years away. The two larger ones, NGC 3169 and NGC 3166, are only about 50,000 light-years apart. NGC 3169 seems active with evident distortion, and the smaller ones, NGC 3166 and NGC 3165, seem rather quiescent.
Telescope: Meade 8" LX200R @ f/5 Camera: SBIG ST-2000XM Exposure: L=90min, R=B=30min, G=25min |
Stephan's Quintet - This group of 5 galaxies in Pegasus, discovered in 1877 by Edouard Stephan, consists of 4 interacting galaxies (NGC 7317, 7318a, 7318b and 7319) about 300 million light-years away and the blue foreground galaxy, NGC 7320, about 40 million light-years away. The small galaxy to the left of the group, NGC 7320c, is interacting with the other 4 interacting galaxies, and the 5 form the compact galaxy group, Hickson 92. Halton Arp, famous for his catalog of "peculiar" galaxies (Stephan's Quintet is Arp 319), has argued that the physical characteristics of Stephan's Quintet provide evidence against the Big Bang (see http://www.electric-cosmos.org/arp.htm). The total exposure time was 5 hours 21 minutes.
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NGC 660 - This is a polar ring galaxy about 45 million light-years away in Pisces. It is a bit of an optical illusion, but, if you stare at it long enough, you will see a large ring almost edge on and tilted about 45° counterclockwise from vertical. This ring is being pierced by a smaller galaxy moving almost horizontally through it. It has been suggested that the dark dust clouds in the ring indicate that the larger galaxy is rich in metals. The exposure times for this image are L=4hr, R=G=B=60min.
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NGC 3718 and NGC 3729 - The gravitational interactions of these two spiral galaxies, 52 million light-years away in the constellation, Ursa Major, have distorted both of them. NGC 3718 in the center of the image is the more warped and twisted of the two, with a helical dust lane threaded through it. At the bottom of the image is the galaxy group, Hickson 56, which is over 400 million light-years away.
Telescope: Meade 14" LX200GPS @ f/7 with Starizona SCT corrector Camera: SBIG ST-8300C Autoguiding: Starlight Xpress OAG with Meade DSI using PHD2 Exposure: 10 X 30 minutes = 5 hrs |
Arp 286 - This galaxy group, which includes NGC 5566 (center), NGC 5560 (top) and NGC 5569 (bottom left), is about 80 million light-years away in the direction of Virgo. NGC 5566 and 5560 are both deformed and probably interacting. NGC 5569 shows no signs of interaction. It was taken in Mastersonville, PA, and the seeing was not very good. The total exposure time for this image was 3 hrs.
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Arp 94 - Arp 94 is about 120 million light-years away in the direction of Leo. It consists of a small elliptical galaxy, NGC 3226, which is merging with a larger Seyfert galaxy, NGC 3227, and causing gas to spew out everywhere. Faint wisps can be seen on either side of NGC 3227, probably indicating that the two galaxies have orbited each other several times. There are also lots of nice background galaxies, including what appears to be another interacting pair in the upper right part of the image.
I started this image in Chiefland (1 hour of luminance) and finished it in Mastersonville, PA (2 more hours of luminance and 1 hour each of R,G and B). |
NGC 4490 and NGC 4485 (Cocoon Galaxy) - These are about 45 million light years away in the direction of Canes Venatici. Originally spiral galaxies, they have been distorted by each other. They are past perigalacticon and are speeding away from each other, now about 24,000 light years apart. The total exposure time for this image was 6 hrs.
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NGC 772 – This spiral galaxy is the largest in a cluster of galaxies named Arp 78, which is about 130 million light years away. The distortion of NGC 772 and the gas and dust streams indicate that it is probably interacting with two dwarf galaxies to the south (below in the image). The larger, closer dwarf galaxy is NGC 770 and the smaller one is PGC 212884. The total exposure time for this image was 9 hr 50 min.
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