Ursa Major is one of those few stars that have caught astronomers attentions. The most interesting thing about the pulsar is that is believed to have exceeding the Eddington Limit. The Limit is the theorectical limit of the brightness of a star given its mass. It is named after Sir Arthur Eddington in the first part of the twentieth century. Oxford Reference
It is not the only star that seemingly breaks the limit, the star R136a1 also breaks this limit, it is 265 solar masses and is believed to have been at least 320 solar masses when it was created. Britannica The star M82 X-2 is shining at more than 100 times than what it should be. It is the brightest pulsar so far discovered. The object pulses ever 1.37 second and the pulsations change every 2.5 days. Harvard
There is also a M82 X-1 ultraluminous X-ray sources (ULX), also in the same galaxy. Whilst X-2 is a pulsar, X-1 is a black hole. NASA. ULX have not been found in our galaxy yet but in other galaxies. M82 X-2 was discovered by Dr. Steve Fossey and students at the University College London in 2014. Astronomy Now
The location of the star in the night sky is determined by the Right Ascension (R.A.) and Declination (Dec.), these are equivalent to the Longitude and Latitude on the Earth. The Right Ascension is how far expressed in time (hh:mm:ss) the star is along the celestial equator. If the R.A. is positive then its eastwards. The Declination is how far north or south the star is compared to the celestial equator and is expressed in degrees. For M82 X-2, the location is 09h 55m 51.0 and +69° 40` 45 .
M82 X-2 has a spectral type of P.
|Primary / Proper / Traditional Name||M82 X-2|
|Constellation's Main Star||No|
|Multiple Star System||No / Unknown|
|Galaxy||Messier 82, Cigar Galaxy|
|Right Ascension (R.A.)||09h 55m 51.0|
|Declination (Dec.)||+69° 40` 45|