Messier 105 or M105, also known as NGC 3379, is an

elliptical galaxy An elliptical galaxy is a type of galaxy with an approximately ellipsoidal shape and a smooth, nearly featureless image. They are one of the four main classes of galaxy described by Edwin Hubble in his Hubble sequence and 1936 work ''The R ...

36.6 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

equatorial Equatorial may refer to something related to: *Earth's equator **the tropics, the Earth's equatorial region **tropical climate *the Celestial equator ** equatorial orbit **equatorial coordinate system ** equatorial mount, of telescopes * equatorial ...

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 ...

of Leo. It is the biggest elliptical galaxy in the Messier catalogue that is not in the Virgo cluster. It was discovered by

Pierre Méchain Pierre François André Méchain (; 16 August 1744 – 20 September 1804) was a French astronomer and surveyor who, with Charles Messier, was a major contributor to the early study of deep-sky objects and comets. Life Pierre Méchain was born i ...

in 1781, just a few days after he discovered the nearby galaxies

Messier 95 Messier 95, also known as M95 or NGC 3351, is a barred spiral galaxy about 33 million light-years away in the zodiac constellation Leo (constellation), Leo. It was discovered by Pierre Méchain in 1781, and catalogued by compatriot Charles Mess ...

and

Messier 96 Messier 96 (also known as M96 or NGC 3368) is an intermediate spiral galaxy about 31 million light-years away in the constellation Leo. Observational history and appearance It was discovered by French astronomer Pierre Méchain in 1781. After ...

. This galaxy is one of a few not object-verified by Messier so omitted in the editions of his Catalogue of his era. It was appended when

Helen S. Hogg Helen Battles Sawyer Hogg (August 1, 1905 – January 28, 1993) was an American-Canadian astronomer who pioneered research into globular clusters and variable stars. She was the first female president of several astronomical organizations and a ...

found a letter by Méchain locating and describing this object which matched those aspects under its first-published name, NGC 3379. It has a morphological classification of E1, indicating a standard 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 ...

of 10%. The major axis is aligned along a

position angle In astronomy, position angle (usually abbreviated PA) is the convention for measuring angles on the sky. The International Astronomical Union defines it as the angle measured relative to the north celestial pole (NCP), turning positive into the d ...

of 71°.

Isophote In geometry, an isophote is a curve on an illuminated surface that connects points of equal brightness. One supposes that the illumination is done by parallel light and the brightness is measured by the following scalar product: :b(P)= \vec n(P) ...

s of the galaxy are near perfect ellipses, twisting no more than 5° out of alignment, with changes in

ellipticity 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 ...

of no more than 0.06. There is no fine structure apparent in the isophotes, such as ripples. Observation of giant stars in the halo indicate there are two general populations: a dominant metal-rich subpopulation and a weaker metal-poor group. Messier 105 is known to have 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 obj ...

at its core whose mass is estimated to be between and . The galaxy has a weak

active galactic nucleus An active galactic nucleus (AGN) is a compact region at the center of a galaxy that has a much-higher-than-normal luminosity over at least some portion of the electromagnetic spectrum with characteristics indicating that the luminosity is not pr ...

of the

LINER A low-ionization nuclear emission-line region (LINER) is a type of galactic nucleus that is defined by its spectral line emission. The spectra typically include line emission from weakly ionized or neutral atoms, such as O, O+, N+, and S+. ...

type with a spectral class of L2/T2, meaning no broad Hα line and intermediate

emission line A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from emission or absorption of light in a narrow frequency range, compared with the nearby frequencies. Spectral lines are often used to iden ...

ratios between a LINER and a

H II region An H II region or HII region is a region of interstellar atomic hydrogen that is ionized. It is typically in a molecular cloud of partially ionized gas in which star formation has recently taken place, with a size ranging from one to hundreds ...

. The galaxy also contains a few young

star A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...

s and stellar clusters, suggesting some elliptical galaxies still form new stars, but very slowly. This galaxy, along with its companion the barred

lenticular galaxy A lenticular galaxy (denoted S0) is a type of galaxy intermediate between an elliptical (denoted E) and a spiral galaxy in galaxy morphological classification schemes. It contains a large-scale disc but does not have large-scale spiral arms. L ...

NGC 3384 NGC 3384 is an elliptical galaxy in the constellation Leo. The galaxy was discovered by William Herschel in 1784 as part of the Herschel 400 Catalogue. The high age of the stars in the central region of NGC 3384 was confirmed after analysis of ...

, is surrounded by an enormous ring of

neutral hydrogen The hydrogen line, 21 centimeter line, or H I line is the electromagnetic radiation spectral line that is created by a change in the energy state of neutral hydrogen atoms. This electromagnetic radiation has a precise frequency of , w ...

with a radius of and a mass of where

star formation Star formation is the process by which dense regions within molecular clouds in The "medium" is present further soon.-->interstellar space

has been detected. Messier 105 is one of several galaxies within the

M96 Group The M96 Group (also known as the Leo I Group) is a group of galaxies in the constellation Leo. This group contains between 8 and 24 galaxies, including three Messier objects. It also contains the Leo Ring. The group is one of many groups tha ...

(also known as the Leo I Group), a

group of galaxies A galaxy group or group of galaxies (GrG) is an aggregation of galaxies comprising about 50 or fewer gravitationally bound members, each at least as luminous as the Milky Way (about 1010 times the luminosity of the Sun); collections of galaxies ...

in the

Leo, the other

Messier objects The Messier objects are a set of 110 astronomical objects catalogued by the French astronomer Charles Messier in his ''Catalogue des Nébuleuses et des Amas d'Étoiles'' (''Catalogue of Nebulae and Star Clusters''). Because Messier was only in ...

of which are M95 and M96.

References and footnotes

External links

*
"StarDate: M105 Fact Sheet"

* {{Ngc35 Elliptical galaxies M96 Group Leo (constellation) 105

Messier 105 Messier 105 or M105, also known as NGC 3379, is an elliptical galaxy 36.6 million light-years away in the equatorial constellation of Leo. It is the biggest elliptical galaxy in the Messier catalogue that is not in the Virgo cluster. It w ...

05902 32256 17810324 Discoveries by Pierre Méchain

See also

References and footnotes

External links