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We suggested that among bright X-ray flares that continue for a few years, some can be caused by tidal gravitational disruption of a star which passed too close to a super massive black hole. We think, if a star passes within the tidal radius of a black hole then the gravity rips the star apart. As the stellar remnant approaches a black hole, its gravitational potential energy is converted into heat through viscous effects. Some of the debris can be ejected, while the remaining part can be ingested by a central super massive black hole. In this case the accretion flow reaches a temperature of about 105K and emits brightly at optical, ultraviolet, and X-ray wavelengths during the period from about 100 days to a few years. Recently, a team led by Elena Seifina found something interesting while looking at the event called “Swift J1644 + 57”. They observed a gamma-ray burst similar to those coming from remote galaxies in the hardest range of the electromagnetic spectrum. But this time it was slightly different so they suspected that they were observing the tidal destruction of the star by a supermassive black hole. Not only, their new idea permitted them to discover a new black hole, but they were able to propose a new approach to measure its mass thanks to the observation of the accretion disk formed around it.Calculations showed that Swift J1644+57 contained a supermassive black hole with a mass of 7×10^6 solar masses. This is an object that we do not see, but which provides high luminosity due to its strong gravitational field and an accretion disk around it.