| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Ursa Major |
| Right ascension | 09h 55m 51.0s |
| Declination | 69° 40′ 45″ |
| Astrometry | |
| Distance | 12 million ly (3.5 million pc) |
| Other designations | |
| Database references | |
| SIMBAD | data |
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M82 X-2 is an X-ray pulsar located in the galaxy Messier 82, approximately 12 million light-years from Earth.[2] It is exceptionally luminous, radiating energy equivalent to approximately ten million Suns. This object is part of a binary system: If the pulsar is of an average size, 1.4 M☉, then its companion is at least 5.2 M☉.[3] On average, the pulsar rotates every 1.37 seconds, and revolves around its more massive companion every 2.5 days.[4]
M82 X-2 is an ultraluminous X-ray source (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 in January 2014 that X-2's true nature was uncovered.[5][6] Scientists looking at data from the NuSTAR spacecraft noticed a pulsing in the X-ray spectrum coming from near the supernova in Messier 82.[2][7] Data from the Chandra and Swift spacecraft was used to verify the NuSTAR findings and provide the necessary spatial resolution to determine the exact source.[3][4] 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.[1] LXs). In 2023 new NuSTAR data confirmed that it exceeded the Eddington limit.[8][9]
