M82 X-2

From Wikipedia, the free encyclopedia
Jump to navigation Jump to search

M82 X-2
Two ultraluminous X-ray sources in core of Messier 82 (nustar141008a1).jpg
M82 X-2 glows pink in the X-ray spectrum at the center of Messier 82. M82 X-1 is to its right.[1]
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Ursa Major
Right ascension 09h 55m 51.0s
Declination 69° 40′ 45″
Distance12 million ly
(3.5 million pc)
Other designations
CXOU J095550.9+694044, NuSTAR J095551+6940.8
Database references

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]


  1. ^ a b Smith et al. 1995, p. 204.
  2. ^ a b Stark, Anne M. (9 October 2014). "Dead star shines on". Lawrence Livermore National Laboratory. Archived from the original on 11 October 2014. Retrieved 11 October 2014.
  3. ^ a b Anderson, Janet; Watzke, Megan (8 October 2014). "Suspected Black Hole Unmasked as Ultraluminous Pulsar". NASA. Archived from the original on 16 October 2014. Retrieved 19 October 2014.
  4. ^ a b Smith et al. 1995, p. 202.
  5. ^ Fesenmaier, Kimm (8 October 2014). "NuSTAR Discovers Impossibly Bright Dead Star". Caltech. Archived from the original on 16 October 2014. Retrieved 19 October 2014.
  6. ^ Fesenmaier, Kimm (9 October 2014). "Pulsar as bright as 10 million suns baffles astronomers". Futurity. Archived from the original on 20 October 2014. Retrieved 19 October 2014.
  7. ^ Chou, Felicia; Clavin, Whitney (8 October 2014). "NASA's NuStar Telescope Discovers Shockingly Bright Dead Star". NASA. Archived from the original on 26 October 2014. Retrieved 26 October 2014.