M33 X-7
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Triangulum |
| Right ascension | 01h 33m 34.13s |
| Declination | +30° 32′ 11.3″ |
| Apparent magnitude (V) | +18.70 |
| Characteristics | |
| Spectral type | O7-8III / Black hole |
| Astrometry | |
| Distance | 2700000±70000 ly (840000±20000 pc) |
| Orbit | |
| Period (P) | 3.45301 ± 0.00002 d |
| Semi-major axis (a) | 42.4 ± 1.5 R☉ |
| Eccentricity (e) | 0.0185 ± 0.0077 |
| Inclination (i) | 74.6 ± 1.0° |
| Details | |
| O-type star | |
| Mass | 70 ± 6.9 M☉ |
| Temperature | 35000 ± 1000 K |
| Black hole | |
| Mass | 15.65 ± 1.45 M☉ |
| Radius | 0.000066 ± 0.0000061 R☉ |
| Other designations | |
| 2E 408, 2E 0130.7+3016, RX J0133.5+3032, CXOU J013334.1+303210 | |
| Database references | |
| SIMBAD | data |
M33 X-7 is a black hole binary system in the Triangulum Galaxy. The system is made up of a stellar-mass black hole and a companion star. The black hole in M33 X-7 has an estimated mass of 15.65 times that of the Sun (M☉) (formerly the largest known stellar black hole, though this has now been superseded amongst electromagnetically-observed black holes by an increased mass estimate for Cygnus X-1, and also by many of the LVK-detected binary black hole components). The total mass of the system is estimated to be around 85.7 M☉, which would make it the most massive black hole binary system. The black hole is consuming its partner, a 70 solar mass blue giant star.