VV Orionis
VV Orionis is an eclipsing binary located in the belt region of the constellation Orion. It is a faint naked eye star.
| Observation data Epoch J2000 Equinox | |
|---|---|
| Constellation | Orion |
| Right ascension | 05h 33m 31.44643s[1] |
| Declination | −01° 09′ 21.8666″[1] |
| Apparent magnitude (V) | 5.31 (- 5.55) - 5.66[2] |
| Characteristics | |
| Evolutionary stage | B1V + B4.5V[3] |
| U−B color index | −0.09[4] |
| B−V color index | −0.18[4] |
| Variable type | Eclipsing binary[3] |
| Astrometry | |
| Radial velocity (Rv) | 22.2[5] km/s |
| Proper motion (μ) | RA: -0.82[1] mas/yr Dec.: -1.07[1] mas/yr |
| Parallax (π) | 2.22 ± 0.35[1] mas |
| Distance | approx. 1,500 ly (approx. 450 pc) |
| Orbit[3] | |
| Period (P) | 1.48537423 days |
| Semi-major axis (a) | 13.49 R☉ |
| Eccentricity (e) | 0 |
| Inclination (i) | 85.9° |
| Details[3] | |
| VV Ori A | |
| Mass | 10.9 M☉ |
| Radius | 4.98 R☉ |
| Luminosity | 10,600 L☉ |
| Surface gravity (log g) | 4.08 cgs |
| Temperature | 26,199 K |
| VV Ori B | |
| Mass | 4.09 M☉ |
| Radius | 2.41 R☉ |
| Luminosity | 350 L☉ |
| Surface gravity (log g) | 4.29 cgs |
| Temperature | 16,073 K |
| Other designations | |
| Database references | |
| SIMBAD | data |
The brightness of VV Orionis dips regularly every 18 hours. The peak visual magnitude is 5.3, which varies slowly in between the dips. The minimum brightness of the dips alternates between magnitude 5.55 and 5.66. The deep minima have a somewhat rounded bottom, while the less deep minima have flat bottoms with a constant magnitude for several hours.[3]
The VV Orionis system contains two stars which are very close but are not touching. Their orbit is aligned almost perpendicularly to us and there are both primary and secondary eclipses. During secondary eclipse, the primary transits against the secondary, which produces the flat bottom to the secondary minimum. The orbital alignment allows very precise calculation of the orbit and the properties of the stars, but results from different studies have been unusually inconsistent. The lack of a single consistent solution to the orbit has led to suggestions that there is a third star in the system,[6] but this is now thought unlikely. A circular orbit with the stars only 13.5 R☉ apart can account for the observed brightness and radial velocity changes.[3]
The two stars are both on the main sequence. The primary has a spectral type of B1 and temperature of 26,000 K, while the secondary has a spectral type of B4.5 and a temperature of 16,000 K. The secondary has a mass of four M☉, radius of 2.4 R☉, and bolometric luminosity of 350 L☉. The primary is twice the mass, twice the radius, and thirty times the luminosity.
References
- Van Leeuwen, F. (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. S2CID 18759600.
- 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.
- Terrell, Dirk; Munari, Ulisse; Siviero, Alessandro (2007). "Observational studies of early-type binary stars: VV Orionis". Monthly Notices of the Royal Astronomical Society. 374 (2): 530–534. arXiv:astro-ph/0610202. Bibcode:2007MNRAS.374..530T. doi:10.1111/j.1365-2966.2006.11162.x. S2CID 15450646.
- Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237. Bibcode:2002yCat.2237....0D.
- Wilson, Ralph Elmer (1953). "General catalogue of stellar radial velocities". Washington. Bibcode:1953GCRV..C......0W.
- Chambliss, Carlson R. (1984). "VV Orionis: A well-behaved early-type eclipsing binary system". Astrophysics and Space Science. 99 (1–2): 163–170. Bibcode:1984Ap&SS..99..163C. doi:10.1007/BF00650241. S2CID 189849258.
External links
- VV Orionis Jim Kaler