NGC 5195 (also known as Messier 51b or M51b) is a dwarf galaxy that is interacting with the Whirlpool Galaxy (also known as M51a or NGC 5194). Both galaxies are located approximately 25 million

light-year A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...

s away in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the e ...

Canes Venatici. Together, the two galaxies are one of the most famous interacting galaxy pairs.

History

NGC 5195 was discovered by Pierre Méchain on March 20, 1781.

Interaction with the Whirlpool Galaxy

NGC 5195 and the Whirlpool Galaxy compose one of the most noted interacting galaxy pairs in astronomy. The two galaxies are listed in the '' Atlas of Peculiar Galaxies'' as one of several prominent examples of a spiral galaxy with a companion galaxy. The system was also the subject of very early theoretical investigations into galaxy interactions. The two galaxies are connected by a dust-rich tidal 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. The encounter has significantly enhanced the spiral structure of M51. A 3-pronged "crown"-like structure extends from NGC 5195, where it leads to several massive plumes and streams of stars produced by the interaction with the Whirlpool 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". 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's Chandra 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 the American Astronomical Society (AAS) in Florida, are a dramatic example of 'feedback' between a supermassive black hole and its host galaxy". Webb's report cited

Marie Machacek Marie E. Machacek is an astrophysicist conducting research in the High Energy Astrophysics Division of the Smithsonian Astrophysical Observatory. She earned a BA in physics and mathematics from Coe College, in 1969; an MS in physics from the Un ...

, co-author of the study from the Harvard–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 some stars form. This shows that black holes can create, not just destroy."

Morphology

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 a lenticular galaxy or as an amorphous or irregular galaxy. It has been described as falling outside the standard morphological classification system.

Supernova

Supernova 1945A is the only

supernova A supernova is a powerful and luminous explosion of a star. It has the plural form supernovae or supernovas, and is abbreviated SN or SNe. This transient astronomical event occurs during the last evolutionary stages of a massive star or when ...

that has been detected within NGC 5195. The supernova was found 10″ northwest of the nucleus on April 6, 1945 by

Milton L. Humason Milton La Salle Humason (August 19, 1891 – June 18, 1972) was an American astronomer. He was born in Dodge Center, Minnesota. Biography Humason dropped out of school and had no formal education past the age of 14. Because he loved the m ...

using the telescope at Mount Wilson Observatory. The supernova, classified as a Type I supernova, reached a peak apparent magnitude of 14.0.

References

External links