Great Annihilator
Microquasar
From Wikipedia, the free encyclopedia
1E1740.7-2942, or the Great Annihilator,[3][4] is a Milky Way microquasar, located near the Galactic Center on the sky.[5][2] It likely consists of a black hole and a companion star. It is one of the brightest X-ray sources in the region around the Galactic Center.[6]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Ophiuchus |
| Right ascension | 17h 43m 54.83s[1] |
| Declination | −29° 44′ 42.6″[1] |
| Astrometry | |
| Distance | 16,000 ly (5,000[2] pc) |
| Database references | |
| SIMBAD | data |
The object was first detected in soft X-rays by the Einstein Observatory,[7] and later detected in hard X-rays by the Soviet Granat space observatory.[2] Followup observations by the SIGMA detector on board Granat showed that the object was a variable emitter of massive amounts of photon pairs at 511 keV, which usually indicates the annihilation of an electron-positron pair.[8][9] This led to the nickname, "Great Annihilator."[10] Early observations also showed a spectrum similar to that of the Cygnus X-l, a black hole with a stellar companion, which suggested that Great Annihilator was also a stellar mass black hole.[8]
The object also has a radio source counterpart that emits jets approximately 1.5 pc (5 ly) long.[11] These jets are probably synchrotron emission from positron-electron pairs streaming out at high velocities from the source of antimatter. Modeling of the observed precession of these jets gives an object distance of approximately 5 kpc (or 16,000 ly).[2] This means that while the object is likely located along our line of sight towards the center of the Milky Way, it may be closer to us than Sagittarius A*, the black hole at the center of our galaxy.