Markarian 421 (Mrk 421, Mkn 421) is a

blazar A blazar is an active galactic nucleus (AGN) with a relativistic jet (a jet composed of ionized matter traveling at nearly the speed of light) directed very nearly towards an observer. Relativistic beaming of electromagnetic radiation from the ...

located in the constellation

Ursa Major Ursa Major (; also known as the Great Bear) is a constellation in the northern sky, whose associated mythology likely dates back into prehistory. Its Latin name means "greater (or larger) bear," referring to and contrasting it with nearby Ursa ...

. The object is an

active galaxy 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 prod ...

and a

BL Lacertae object A BL Lacertae object or BL Lac object is a type of active galactic nucleus (AGN) or a galaxy with such an AGN, named after its prototype, BL Lacertae. In contrast to other types of active galactic nuclei, BL Lacs are characterized by rapid and l ...

, and is a strong source of

gamma rays A gamma ray, also known as gamma radiation (symbol γ or \gamma), is a penetrating form of electromagnetic radiation arising from the radioactive decay of atomic nuclei. It consists of the shortest wavelength electromagnetic waves, typically ...

. It is about 397 million light-years (redshift: z=0.0308 eq. 122M pc) to 434 million light-years (133Mpc) from the Earth. It is one of the closest blazars to

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

, making it one of the brightest

quasars A quasar is an extremely luminous active galactic nucleus (AGN). It is pronounced , and sometimes known as a quasi-stellar object, abbreviated QSO. This emission from a galaxy nucleus is powered by a supermassive black hole with a mass rangi ...

in the

night sky The night sky is the nighttime appearance of astronomical object, celestial objects like stars, planets, and the Moon, which are visible in a clear sky between sunset and sunrise, when the Sun is below the horizon. Natural light sources in a ...

. It is suspected 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 ob ...

(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 ray Very-high-energy gamma ray (VHEGR) denotes gamma radiation with photon energies of 100 GeV ( gigaelectronvolt) to 100 TeV (teraelectronvolt), i.e., 1011 to 1014 electronvolts. This is approximately equal to wavelengths between 10−17 and 10−2 ...

s (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 The Whole Earth Blazar Telescope (WEBT) is an international consortium of astronomers created in 1997, with the aim to study a particular category of Active Galactic Nuclei (AGN) called blazars, which are characterized by strong and fast brightness ...

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.

References

External links

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Focus on Markarian 421
* BL Lacertae objects Ursa Major (constellation) Blazars Discoveries by Benjamin Markarian Markarian galaxies 06132 033452 {{Galaxy-stub