| NGC 5195 | |
|---|---|
 AHubble Space Telescope (HST) image of Messier 51. M51A (theWhirlpool Galaxy) is the spiral galaxy on the left. NGC 5195 is the galaxy in the top right corner. | |
| Observation data (J2000epoch) | |
| Constellation | Canes Venatici[1] |
| Right ascension | 13h 29m 59.6s[2] |
| Declination | +47° 15′ 58″[2] |
| Redshift | 465 ± 10 km/s[2] |
| Distance | 25 ± 3Mly (7.7 ± 1.0Mpc)[3] |
| Apparent magnitude (V) | 10.5[2] |
| Characteristics | |
| Type | Amorphous or SB0 pec[4] |
| Size | 59,500ly (18.24kpc) (estimated)[2] |
| Apparent size (V) | 5′.8 × 4′.6[2] |
| Other designations | |
| Messier 51b, HOLM 526B,IRAS 13278+4731,Arp 85,UGC 8494,MCG +08-25-014,PGC 47413,CGCG 246-009,VV 001b[2] | |
NGC 5195 (also known asMessier 51b orM51b) is adwarf galaxy that is interacting with theWhirlpool Galaxy (also known as M51a or NGC 5194). Both galaxies are located approximately 25 millionlight-years away in theconstellationCanes Venatici. Together, the two galaxies are one of the most famousinteracting galaxy pairs.
NGC 5195 was discovered byPierre Méchain on March 20, 1781.[5]
NGC 5195 and the Whirlpool Galaxy compose one of the most noted interacting galaxy pairs in astronomy. The two galaxies are listed in theAtlas of Peculiar Galaxies as one of several prominent examples of a spiral galaxy with a companion galaxy.[6] The system was also the subject of very early theoretical investigations into galaxy interactions.[7] The two galaxies are connected by a dust-richtidal bridge. The dust in this tidal bridge can be seen silhouetted against the center of NGC 5195. This demonstrates that NGC 5195 appears to lie behind the Whirlpool Galaxy.[4] The encounter has significantly enhanced the spiral structure of M51.[citation needed]
A three-pronged structure extends from NGC 5195. The middle prong seems to be bluer than the other prongs, suggesting that this feature is an extension of the Whirlpool Galaxy’s tidal tails. The structure leads to several massive plumes and streams of stars produced by the interaction with the aforementioned grand-design spiral galaxy. One massive plume is called the "Northwest Plume". However, diffuse high-speed gas within the plume suggests an origin within the Whirlpool Galaxy and not NGC 5195. The Northwest plume partially overlaps and blends it with two stellar streams extending from NGC 5195. Unlike the northwest plume, the stellar streams are bifurcated and similar in color to NGC 5195. A 2015 study observing the Whirlpool galaxy and its companion found two new and very faint tidal structures. One of them is called the "South Plume" while the other one is called the "Northeast Plume".[8]
In January 2016,BBC science reporter Jonathan Webb said, "Astronomers have spotted two huge waves of gas being 'burped' by the black hole at the heart of a nearby galaxy. The swathes of hot gas, detected in X-ray images from NASA'sChandra space telescope, appear to be sweeping cooler hydrogen gas ahead of them. This vast, rippling belch is taking place in NGC 5195 – a small, neglected sibling of the 'Whirlpool Galaxy', 26 million light years away. That makes it one of the closest black holes blasting gas in this way". He added, "The findings, presented at the 227th meeting of theAmerican Astronomical Society (AAS) in Florida, are a dramatic example of 'feedback' between asupermassive black hole and its host galaxy".[9] Webb's report citedMarie Machacek, co-author of the study from theHarvard–Smithsonian Center for Astrophysics (CFA), as saying, "We think that feedback keeps galaxies from becoming too large ... But at the same time, it can be responsible for how somestars form. This shows that black holes can create, not just destroy."[9]
As a consequence of the gravitational interaction with the Whirlpool Galaxy, NGC 5195 is highly distorted. Classification of its morphology is difficult, as it is sometimes identified as alenticular galaxy or as an amorphous orirregular galaxy.[4] It has been described as falling outside thestandard morphological classification system.[4]
SN 1945A is the onlysupernova that has been detected within NGC 5195.[2] It was found 10″ northwest of the nucleus on April 6, 1945, byMilton L. Humason using the 100-inch (2.5 m) telescope atMount Wilson Observatory. The supernova, classified as aType I supernova, reached a peakapparent magnitude of 14.0.[10]
