MAXI J1820+070
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| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Ophiuchus |
| Right ascension | 18h 20m 21.942s[1] |
| Declination | +07° 11′ 07.28″[1] |
| Apparent magnitude (V) | 12±19[2] |
| Characteristics | |
| Spectral type | K3-K5[3] |
| Astrometry | |
| Proper motion (μ) | RA: −3.093 mas/yr[1] Dec.: −6.286 mas/yr[1] |
| Parallax (π) | 0.3692±0.078 mas[1] |
| Distance | 9,700 ± 1,100 ly (2,960±330[4] pc) |
| Orbit[2] | |
| Period (P) | 0.68549 d |
| Eccentricity (e) | 0.026 |
| Inclination (i) | 66–81° |
| Details | |
| Primary | |
| Mass | 5 to 10[5] M☉ |
| Secondary | |
| Mass | 0.49±0.10[5] M☉ |
| Other designations | |
| ASASSN-18ey, MAXI J1820+070, TIC 317984780, 2MASS J18202194+0711073, WISE J182021.94+071107.2[6] | |
| Database references | |
| SIMBAD | data |
MAXI J1820+070 is an X-ray binary system in the equatorial constellation of Ophiuchus. It was discovered in 2018, when it underwent a flare event,[7] becoming one of the brightest such objects ever observed (in both the visual and X-ray bands).[2] Based on parallax measurements, it is located at a distance of approximately 9.7 ± 1.1 kly (2.96 ± 0.33 kpc) from the Sun.[4]
This target was discovered March 6, 2018 by the All Sky Automated Survey for SuperNovae at an apparent visual magnitude of 14.88. Previously it had been at magnitudes below 16.7. On March 11, X-ray emission from this source was detected by the MAXI telescope,[7] mounted on the International Space Station.[8] On March 13, the Swift Burst Alert Telescope was triggered by MAXI J1820+070.[9]
Subsequently, the source underwent three re-brightenings that were extensively monitored, before its final optical activity was observed in April 2021. It began fading rapidly in June 2023 and returned to quiescence at its pre-brightening level after five years.[10]
