| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Dorado |
| Right ascension | 05h 39m 38.8284s |
| Declination | −69° 44′ 35.5315″ |
| Apparent magnitude (V) | 14.612 ± 0.171[1] |
| Characteristics | |
| Evolutionary stage | X-ray binary |
| Spectral type | O8 IIIf or O8 f?p[2] |
| Astrometry | |
| Radial velocity (Rv) | 309.12 ± 0.333[2] km/s |
| Proper motion (μ) | RA: 1.889 ± 0.020mas/yr[3] Dec.: 0.622 ± 0.023mas/yr[3] |
| Distance | 180,000 ly (55,000 pc)[2] |
| Orbit[4] | |
| Primary | giant star |
| Companion | black hole |
| Period (P) | 3.90917 ± 0.00005 days |
| Semi-major axis (a) | 36.49 ± 1.51R☉ |
| Eccentricity (e) | <0.0256 ± 0.0066 |
| Inclination (i) | 36.38 ± 2.02° |
| Semi-amplitude (K2) (secondary) | 71.61 ± 1.10 km/s |
| Details[4] | |
| star | |
| Mass | 31.79 ± 3.48 M☉ |
| Radius | 17.0 ± 0.8 R☉ |
| Surface gravity (log g) | 3.485 ± 0.018 cgs |
| Temperature | 33,000 to 35,000[2] K |
| Rotational velocity (v sin i) | 129.9 ± 2.2 km/s |
| Age | 5 Myr |
| black hole | |
| Mass | 10.91 ± 1.41 M☉ |
| Other designations | |
| 2MASS J05393883-6944356,2E 1522,1RXS J053938.8-694515 | |
| Database references | |
| SIMBAD | data |
LMC X-1 is the first X-ray source detected in theLarge Magellanic Cloud.[4] It was discovered in 1969, using data from an instrument carried by a SandiaTerrier-Sandhawk sounding rocket, launched from theJohnston Atoll on October 29, 1968.[5][6] LMC X-1 is a persistently luminous X-ray binary.[4]
In the 80s Hutchings et al. performed spectroscopic follow-up observations of the optical counterpart and found an orbital period of about 4 days and a secondary mass of about 6M☉, making the secondary astellar mass black hole.[7][8] The orbital period later turned out to be shorter at around 3.9 days.[9] The optical counterpart is also called "star 32". The black hole has a mass of around 11M☉ and the star has a mass of around 32M☉ and a radius of 17R☉. With this radius the star nearly fills itsRoche lobe and it is predicted that it will encounter its Roche lobe in a few hundred thousand years. Once it reaches its Roche lobe, it will begin rapid and possibly unstable mass transfer to its companion.[4]
The X-ray source is surrounded by a nebula, which is the only nebula energized by an X-ray binary. It is suspected that the nebula is abow shock nebula. The nebula is also detected inradio wavelengths withATCA imaging. A possible origin of LMC X-1 is thestar cluster[NKN2005] N159-O1. Other possible origins areNGC 2077,NGC 2080,NGC 2085 andNGC 2086. In the scenario of N159-O1 being the origin, the progenitor to the black hole would have a mass of about 60M☉, meaning it was the most massive member of this star cluster.[2]
