Benjamin Markarian

Benjamin "Benik" Egishevitch Markarian (Armenian: Բենիամին Եղիշեի Մարգարյան; born on 29 November, 1913 in Shulaver, Tiflis Governorate; died on 29 September, 1985 in Yerevan, Armenian SSR) was an Armenian astrophysicist. Markarian's Chain (of galaxies) was named after him when he discovered that this string of galaxies moves with a common motion. He is also the namesake of a catalog of compact, optically bright galaxies (including both starbursts and AGNs) known as Markarian galaxies.

Benjamin Markarian 2013 Armenian stamp
Benjamin Markarian on a 2013 Armenian stamp

External links

See also

  • Category:Discoveries by Benjamin Markarian
Guillermo Haro

Guillermo Haro Barraza (Spanish pronunciation: [ɡiˈʝeɾmo ˈaɾo βaˈrasa]; 21 March 1913 – 26 April 1988) was a Mexican astronomer. Through his own astronomical research and the formation of new institutions, Haro was influential in the development of modern observational astronomy in Mexico. Internationally, he is best known for his contribution to the discovery of Herbig–Haro objects.

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List of galaxies named after people

A small number of galaxies or galaxy groups have been named after individual people. In most cases, the named individual was the person who discovered the object, who first brought attention to it, or who first studied it scientifically.

Many of the brighter galaxies visible from the Northern Hemisphere have Messier numbers, named after Charles Messier. For instance, the Andromeda Galaxy is Messier 31 and the Whirlpool Galaxy is Messier 51. There are a few other comprehensive catalogs that assign the cataloguer's name to galaxies. For instance, Markarian galaxies, named after Benjamin Markarian, are galaxies with excess blue and ultraviolet emission; galaxies in the Atlas of Peculiar Galaxies are assigned an Arp number after Halton Arp who produced the catalog; etc. Objects in these catalogs are excluded below, except in cases where they carry the name of an additional person.

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Markarian's Chain

Markarian's Chain is a stretch of galaxies that forms part of the Virgo Cluster. When viewed from Earth, the galaxies lie along a smoothly curved line. Charles Messier first discovered two of the galaxies, M84 and M86, in 1781. The other galaxies seen in the chain were first mentioned in John Louis Emil Dreyer's New General Catalogue, published in 1888. It was ultimately named after the Armenian astrophysicist, Benjamin Markarian, who discovered their common motion in the early 1960s. Member galaxies include M84 (NGC 4374), M86 (NGC 4406), NGC 4477, NGC 4473, NGC 4461, NGC 4458, NGC 4438 and NGC 4435. It is located at RA 12h 27m and Dec +13° 10′.

The bright members of the chain are visible through small telescopes. Larger telescopes can be used to view the fainter galaxies.At least seven galaxies in the chain appear to move coherently, although others appear to be superposed by chance. Six of the points on the chain can be marked by galaxies. The other two points are pairs of galaxies.

Markarian 177

Markarian 177 is a blue compact dwarf galaxy located 90,000,000 ly (28 Mpc) away, at the constellation of Ursa Major, in the bowl of the Big Dipper asterism. It was discovered by the astronomer Benjamin Markarian.

Markarian 177 is a peculiar galaxy that is receding from us at a rate of 2425 km/s. It has a visual apparent size of 0.41×0.34 arcmin.

Markarian 421

Markarian 421 (Mrk 421, Mkn 421) is a blazar located in the constellation Ursa Major. The object is an active galaxy and a BL Lacertae object, and is a strong source of gamma rays. It is about 397 million light-years (redshift: z=0.0308 eq. 122Mpc) to 434 million light-years (133Mpc) from the Earth. It is one of the closest blazars to Earth, making it one of the brightest quasars in the night sky. It is suspected to have a supermassive black hole (SMBH) at its center due to its active nature. An early-type high inclination spiral galaxy (Markarian 421-5) is located 14 arc-seconds northeast of Markarian 421.

It was first determined to be a very high energy gamma ray emitter in 1992 by M. Punch at the Whipple Observatory, and an extremely rapid outburst in very-high-energy gamma rays (15-minute rise-time) was measured in 1996 by J. Gaidos at Whipple Observatory Markarian 421 also had an outburst in 2001 and is monitored by the Whole Earth Blazar Telescope project.Due to its brightness (around 13.3 magnitude, max. 11.6 mag. and min. 16 mag.) the object can also be viewed by amateurs in smaller telescopes.

Markarian 501

Markarian 501 (or Mrk 501) is a galaxy with a spectrum extending to the highest energy gamma rays. It is a blazar or BL Lac object, which is an active galactic nucleus with a jet that is shooting towards the Earth.

In the very-high-energy gamma ray region of the spectrum, at energies above 1011 eV (0.1 TeV), it is the brightest object in the sky. The object has a redshift of z = 0.034.The galaxy hosting the blazar was studied and catalogued by Benjamin Markarian in 1974. It was first determined to be a very high energy gamma ray emitter in 1996 by J. Quinn at the Whipple Observatory.

Markarian galaxies

The Markarian galaxies are a class of galaxies that have nuclei with excessive amounts of ultraviolet emissions compared with other galaxies. Benjamin Markarian drew attention to these types of galaxies starting in 1963. The nuclei of the galaxies had a blue colour, associated to stars in the classes from O to A. This blue core did not match the rest of the galaxy. The spectrum in detail tends to show a continuum that Markarian concluded was produced non-thermally. Most of these have emission lines and are characterized by highly energetic activity.

Markarian Catalogue entries are of the form "Markarian ####", and can frequently use the abbreviations Mrk, Mkr, Mkn; and rarely Ma, Mk, Mark.

Seyfert galaxy

Seyfert galaxies are one of the two largest groups of active galaxies, along with quasars. They have quasar-like nuclei (very luminous, distant and bright sources of electromagnetic radiation) with very high surface brightnesses whose spectra reveal strong, high-ionisation emission lines, but unlike quasars, their host galaxies are clearly detectable.Seyfert galaxies account for about 10% of all galaxies and are some of the most intensely studied objects in astronomy, as they are thought to be powered by the same phenomena that occur in quasars, although they are closer and less luminous than quasars. These galaxies have supermassive black holes at their centers which are surrounded by accretion discs of in-falling material. The accretion discs are believed to be the source of the observed ultraviolet radiation. Ultraviolet emission and absorption lines provide the best diagnostics for the composition of the surrounding material.Seen in visible light, most Seyfert galaxies look like normal spiral galaxies, but when studied under other wavelengths, it becomes clear that the luminosity of their cores is of comparable intensity to the luminosity of whole galaxies the size of the Milky Way.Seyfert galaxies are named after Carl Seyfert, who first described this class in 1943.

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