Messier 110, or M110, also known as NGC 205, is a dwarf elliptical galaxy that is a

satellite A satellite or an artificial satellite is an object, typically a spacecraft, placed into orbit around a celestial body. They have a variety of uses, including communication relay, weather forecasting, navigation ( GPS), broadcasting, scient ...

of the Andromeda Galaxy in the Local Group.

Early observational history

Charles Messier never included the galaxy in his list, but it was depicted by him, together with M32, on his drawing of "Nébuleuse D'Andromède", later known as the Andromeda Galaxy. A label of the drawing indicates that Messier first saw the object in 1773. M110 was independently discovered by Caroline Herschel on August 27, 1783; her brother

William Herschel Frederick William Herschel ( ; ; 15 November 1738 – 25 August 1822) was a German-British astronomer and composer. He frequently collaborated with his younger sister and fellow astronomer Caroline Herschel. Born in the Electorate of Hanover ...

described her discovery in 1785. From p. 262: "There is a very considerable, broad, pretty faint, small nebula near it he Andromeda galaxy, M31 my Sister arolinediscovered it August 27, 1783, with a Newtonian 2-feet sweeper. It shews the same faint colour with the great one, and is, no doubt, in the neighborhood of it. It is not 32… ; but this is about two-thirds of a degree north preceding it, in a line parallel to β

eta Eta ( ; uppercase , lowercase ; ''ē̂ta'' or ''ita'' ) is the seventh letter of the Greek alphabet, representing the close front unrounded vowel, . Originally denoting the voiceless glottal fricative, , in most dialects of Ancient Greek, it ...

and ν uAndromedae." The suggestion to assign the galaxy a Messier number was made by Kenneth Glyn Jones in 1967, making it the last member of the Messier List.

Properties

This galaxy has a morphological classification of pec dE5, indicating a dwarf elliptical galaxy with a

flattening Flattening is a measure of the compression of a circle or sphere along a diameter to form an ellipse or an ellipsoid of revolution (spheroid) respectively. Other terms used are ellipticity, or oblateness. The usual notation for flattening is f ...

of 50%. It is designated peculiar (pec) due to patches of dust and young blue stars near its center. This is unusual for dwarf elliptical galaxies in general, and the reason is unclear. Unlike M32, M110 lacks evidence for a

supermassive black hole A supermassive black hole (SMBH or sometimes SBH) is the largest type of black hole, with its mass being on the order of hundreds of thousands, or millions to billions, of times the mass of the Sun (). Black holes are a class of astronomical ...

at its center. The interstellar dust in M110 has a mass of with a temperature of , and the interstellar gas has . The inner region has sweeping deficiencies in its

interstellar medium The interstellar medium (ISM) is the matter and radiation that exists in the outer space, space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, as well as cosmic dust, dust and cosmic rays. It f ...

IM, most likely expelled by

supernova A supernova (: supernovae or supernovas) is a powerful and luminous explosion of a star. A supernova occurs during the last stellar evolution, evolutionary stages of a massive star, or when a white dwarf is triggered into runaway nuclear fusion ...

explosions. Tidal interactions with M31 may have stripped away a significant fraction of the expelled gas and dust, leaving the galaxy as a whole, as it presents, deficient in its IM density. Novae have been detected in this galaxy, including one discovered in 1999, and another in 2002. The latter, designated EQ J004015.8+414420, had also been captured in images taken by the

Sloan Digital Sky Survey The Sloan Digital Sky Survey or SDSS is a major multi-spectral imaging and spectroscopic redshift survey using a dedicated 2.5-m wide-angle optical telescope at Apache Point Observatory in New Mexico, United States. The project began in 2000 a ...

(SDSS) that October.

Local context

About half of the Andromeda's satellite galaxies are orbiting it in a plane, with 14 out of 16 following the same sense of rotation. One theory proposes that these 16 once belonged to a subhalo surrounding M110, then the group was broken up by

tidal force The tidal force or tide-generating force is the difference in gravitational attraction between different points in a gravitational field, causing bodies to be pulled unevenly and as a result are being stretched towards the attraction. It is the ...

s during a close encounter with Andromeda.

Notes

References

External links