M82 X-2
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M82 X-2 is an
X-ray pulsar X-ray pulsars or accretion-powered pulsars are a class of astronomical objects that are X-ray sources displaying strict periodic variations in X-ray intensity. The X-ray periods range from as little as a fraction of a second to as much as several m ...
located in the galaxy
Messier 82 Messier 82 (also known as NGC 3034, Cigar Galaxy or M82) is a starburst galaxy approximately 12 million light-years away in the constellation Ursa Major. It is the second-largest member of the M81 Group, with the D25 isophotal diameter of . It ...
, approximately 12 million light-years from Earth. It is exceptionally luminous, radiating energy equivalent to approximately ten million
Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...
s. This object is part of a
binary system A binary system is a system of two astronomical bodies which are close enough that their gravitational attraction causes them to orbit each other around a barycenter ''(also see animated examples)''. More restrictive definitions require that th ...
: If the pulsar is of an average size, , then its companion is at least . On average, the pulsar rotates every 1.37 seconds, and revolves around its more massive companion every 2.5 days. M82 X-2 is an
ultraluminous X-ray source An ultraluminous X-ray source (ULX) is an astronomical source of X-rays that is less luminous than an active galactic nucleus but is more consistently luminous than any known stellar process (over 1039 erg/s, or 1032 watts), assuming that it radiat ...
(ULX), shining about 100 times brighter than theory suggests something of its mass should be able to. Its brightness is many times higher than the Eddington limit, a basic physics guideline that sets an upper limit on the brightness that an object of a given mass should be able to achieve. Possible explanations for violations of the Eddington limit include geometrical effects arising from the funneling of in-falling material along magnetic field lines. While M82 X-2 was previously known as an X-ray source, it was not until an observation campaign to study the newly discovered supernova
SN 2014J SN 2014J was a type-Ia supernova in Messier 82 (the 'Cigar Galaxy', M82) discovered in mid-January 2014. It was the closest type-Ia supernova discovered for 42 years, and none have been closer . The supernova was discovered by chance during an ...
in January 2014 that X-2's true nature was uncovered. Scientists looking at data from the
NuSTAR NuSTAR (Nuclear Spectroscopic Telescope Array, also named Explorer 93 and SMEX-11) is a NASA space-based X-ray telescope that uses a conical approximation to a Wolter telescope to focus high energy X-rays from astrophysical sources, especiall ...
spacecraft noticed a pulsing in the X-ray spectrum coming from near the supernova in Messier 82. Data from the
Chandra Chandra ( sa, चन्द्र, Candra, shining' or 'moon), also known as Soma ( sa, सोम), is the Hindu god of the Moon, and is associated with the night, plants and vegetation. He is one of the Navagraha (nine planets of Hinduism) a ...
and
Swift Swift or SWIFT most commonly refers to: * SWIFT, an international organization facilitating transactions between banks ** SWIFT code * Swift (programming language) * Swift (bird), a family of birds It may also refer to: Organizations * SWIFT, ...
spacecraft was used to verify the NuSTAR findings and provide the necessary
spatial resolution In physics and geosciences, the term spatial resolution refers to distance between independent measurements, or the physical dimension that represents a pixel of the image. While in some instruments, like cameras and telescopes, spatial resolut ...
to determine the exact source. After combining the NuSTAR and Chandra data, scientists were able to discern that M82 X-2 emitted both an X-ray beam and continuous broad X-ray radiation.


See also

* M82 X-1


References


Bibliography

* {{Stars of Ursa Major X-ray pulsars X-ray binaries Ursa Major (constellation) Unsolved problems in physics