Epoch J2000 Equinox J2000
|Right ascension||02h 40m 31.6643s|
|Declination||+61° 13′ 45.592″|
|Apparent magnitude (V)||10.61 - 10.83|
|U−B color index||−0.34|
|B−V color index||+0.86|
|Variable type||High-mass X-ray binary|
|Radial velocity (Rv)||−41.41 km/s|
|Proper motion (μ)|| RA: 0.27 mas/yr |
Dec.: 2.38 mas/yr
|Parallax (π)||0.45 ± 0.23 mas|
|Distance||approx. 7,000 ly |
(approx. 2,000 pc)
LS I +61 303 is an 11th magnitude star that was recognised as a luminous object and catalogued as an OB star in 1959. It was included in the Hipparcos survey as HIP 12469 and had its parallax measured at 5.65±2.28 mas, revised to −0.29±2.99 mas in the new reduction. The first Gaia data release gave a parallax of 0.45±0.23 mas.
The galactic radio source GT 0236+610 was found at the same position as LS I +61 303. A gamma-ray source 2CG 135+01 was found within a degree of its position, and the MAGIC telescope confirmed that LS I +61 303 was the source of the gamma-rays. Periodic X-ray outbursts also occur.
LS I +61 303 shows the spectrum of a Be star, a B0 main sequence star with disk that produces emission lines in its spectrum. Variations in its radial velocity show that it is in orbit with an unseen compact object having a mass between 1 and 4 M☉. The pair orbit every 36.406 days. Although the uncertain mass of the compact object would allow it to be a neutron star, it is thought likely to be a black hole.
LS I +61 303 varies slightly at optical wavelengths, but measurements going back to 1887 show no obvious period. It also shows regular x-ray outbursts coinciding with its orbital period, and strong radio variability. It was given the variable star designation V615 Cassiopeiae.
LS I +61 303 emits HE and VHE (High Energy and Very High Energy) gamma rays. It is only one of several known star systems that produce such energetic rays. Other two systems are PSR B1259-63, LS 5039 and HESS J0632+057.
- Gaia Collaboration (2016). "Gaia Data Release 1". Astronomy & Astrophysics. 595: A2. arXiv:1609.04172. Bibcode:2016A&A...595A...2G. doi:10.1051/0004-6361/201629512.
- Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/gcvs. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
- Paredes, Josep M; Ribó, Marc; Bosch-Ramon, Valentí; West, Jennifer R; Butt, Yousaf M; Torres, Diego F; Martí, Josep (2007). "Chandra Observations of the Gamma-Ray Binary LS I +61 303: Extended X-Ray Structure?". The Astrophysical Journal Letters. 664 (1): L39–L42. arXiv:0706.0877. Bibcode:2007ApJ...664L..39P. doi:10.1086/520674.
- Reig, P; Fabregat, J (2015). "Long-term variability of high-mass X-ray binaries. I. Photometry". Astronomy & Astrophysics. 574: A33. arXiv:1411.7163. Bibcode:2015A&A...574A..33R. doi:10.1051/0004-6361/201425008.
- van Leeuwen, F.; et al. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.
- Hardorp, J; Rohlfs, K; Slettebak, A; Stock, J (1959). "Luminous stars in the Northern Milky Way. Part I". Hamburger Sternw. 01. Bibcode:1959LS....C01....0H.
- Albert, J; et al. (2006). "Variable Very-High-Energy Gamma-Ray Emission from the Microquasar LS I +61 303". Science. 312 (5781): 1771–3. arXiv:astro-ph/0605549. Bibcode:2006Sci...312.1771A. doi:10.1126/science.1128177. PMID 16709745.
- Massi, M; Migliari, S; Chernyakova, M (2017). "The black hole candidate LS I +61°0303". Monthly Notices of the Royal Astronomical Society. 468 (3): 3689. arXiv:1704.01335. Bibcode:2017MNRAS.468.3689M. doi:10.1093/mnras/stx778.
- Gregory, P. C; Taylor, A. R; Crampton, D; Hutchings, J. B; Hjellming, R. M; Hogg, D; Hvatum, H; Gottlieb, E. W; Feldman, P. A; Kwok, S (1979). "The radio, optical, X-ray, gamma-ray star LSI +61 deg 303". Astronomical Journal. 84: 1030. Bibcode:1979AJ.....84.1030G. doi:10.1086/112508.
- Astronomers Discovery Very High Energy Gamma-ray Emission From Microquasar (ScienceDaily) May 19, 2006
- MAGIC - Major Atmospheric Gamma Imaging Cerenkov Telescope
- MAGIC Telescope home page
- TeV gamma ray source catalog home page