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Sagittarius A*, abbreviated as Sgr A* (/ ˈ s æ dʒ ˈ eɪ s t ɑːr / SADGE-AY-star [3]), is the supermassive black hole [4] [5] [6] at the Galactic Center of the Milky Way.Viewed from Earth, it is located near the border of the constellations Sagittarius and Scorpius, about 5.6° south of the ecliptic, [7] visually close to the Butterfly Cluster (M6) and Lambda Scorpii.
Sagittarius A (Sgr A) is a complex radio source at the center of the Milky Way, which contains a supermassive black hole. It is located between Scorpius and Sagittarius , and is hidden from view at optical wavelengths by large clouds of cosmic dust in the spiral arms of the Milky Way.
One of the most studied stars is S2, a relatively bright star that also passes close by Sgr A*. As of 2020 [update] , S4714 is the current record holder of closest approach to Sagittarius A*, at about 12.6 astronomical units (1.88 × 10 9 km), almost as close as Saturn gets to the Sun, traveling at about 8% of the speed of light.
It is also slightly eclipsed by an accretion disc around the black hole. The system usually does not produce a significant amount of x-rays, but undergoes outbursts when the x-ray luminosity increases due to accretion onto the black hole driving superluminal jets. [7] V4641 Sgr is a source of ultra-high-energy gamma rays. [8]
A black hole with the mass of a car would have a diameter of about 10 −24 m and take a nanosecond to evaporate, during which time it would briefly have a luminosity of more than 200 times that of the Sun. Lower-mass black holes are expected to evaporate even faster; for example, a black hole of mass 1 TeV/c 2 would take less than 10 −88 ...
OJ 287 core black holes — a BL Lac object with a candidate binary supermassive black hole core system [23] PG 1302-102 – the first binary-cored quasar — a pair of supermassive black holes at the core of this quasar [24] [25] SDSS J120136.02+300305.5 core black holes — a pair of supermassive black holes at the centre of this galaxy [26]
SGR J1745−2900, or PSR J1745−2900, is the first-discovered magnetar orbiting the black hole Sagittarius A*, in the center of the Milky Way. [ 1 ] [ 2 ] The magnetar was discovered in 2013 using the Effelsberg 100-m Radio Telescope , the Nancay Decimetric Radio Telescope , and the Jodrell Bank Lovell Telescope .
While Oppenheimer is remembered in history as the “father of the atomic bomb”, his greatest contribution as a physicist was on the physics of black holes. The work of Oppenheimer and Hartland Snyder helped transform black holes from figments of mathematics to real, physical possibilities – something to be found in the cosmos out there.