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Star system in the constellation Ophiuchus From Wikipedia, the free encyclopedia
V1054 Ophiuchi, together with the star Gliese 643, is a nearby quintuple star system. In the constellation Ophiuchus at a distance of 21.19 light-years. It consists of five stars, all of which are red dwarfs. The alternative designation of Wolf 630 forms the namesake of a moving group of stars that share a similar motion through space.[8]
An ultraviolet band light curve for a flare on V1054 Ophiuchi, plotted from data published by Dal and Evren (2010)[1] | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Ophiuchus |
| Right ascension | 16h 55m 25.2222456607s[2] |
| Declination | −08° 19′ 21.296969682″[2] |
| Apparent magnitude (V) | 9.74/10.34/10.84/11.74/16.80[3] |
| Characteristics | |
| Spectral type | M3 V[4] / M4 Ve[note 1] / M3.5 V[4] / M7.0 V[3] |
| Astrometry | |
| Proper motion (μ) | RA: −817.580±0.052[2] mas/yr Dec.: −898.595±0.040[2] mas/yr |
| Parallax (π) | 153.8754 ± 0.0474 mas[2] |
| Distance | 21.196 ± 0.007 ly (6.499 ± 0.002 pc) |
| Absolute magnitude (MV) | 10.69±0.02 / 11.29±0.05 / 11.79±0.05 / 12.69[3][note 2] |
| VB 8 | |
| Proper motion (μ) | RA: −813.038±0.063[5] mas/yr Dec.: −870.609±0.044[5] mas/yr |
| Parallax (π) | 153.9659 ± 0.0570 mas[5] |
| Distance | 21.184 ± 0.008 ly (6.495 ± 0.002 pc) |
| Absolute magnitude (MV) | 17.75[3] |
| Orbit[4] | |
| Primary | V1054 Oph A |
| Companion | V1054 Oph B |
| Period (P) | 1.717267±0.000039[3] yr |
| Semi-major axis (a) | 0.2273±0.0004" (1.46683 AU[note 3]) |
| Eccentricity (e) | 0.042±0.001 |
| Inclination (i) | 160.3±0.1° |
| Longitude of the node (Ω) | −10.2±0.2° |
| Periastron epoch (T) | MJD 53943±3 |
| Argument of periastron (ω) (secondary) | 306.0±1.5° |
| Orbit[4] | |
| Primary | V1054 Oph Ba |
| Companion | V1054 Oph Bb |
| Period (P) | 2.965509±0.000006 d |
| Semi-major axis (a) | 0.00687[note 4]" (0.04432 AU[note 5]) |
| Eccentricity (e) | 0.0209±0.0008 |
| Inclination (i) | 164.18±0.08° |
| Periastron epoch (T) | MJD 50919.48±0.03 |
| Argument of periastron (ω) (secondary) | 150.0±3.0° |
| Details | |
| V1054 Oph AB | |
| Mass | 0.4155±0.0057 / 0.3466±0.0047 / 0.3143±0.0040[4] M☉ |
| Gliese 643 | |
| Mass | 0.19[3] M☉ |
| Details | |
| VB 8 | |
| Mass | 0.0914+0.0026 −0.0025[6] M☉ |
| Radius | 0.1214+0.0060 −0.0057[6] R☉ |
| Luminosity | 0.000645+0.000004 −0.000005[6] L☉ |
| Temperature | 2,640+65 −64[6] K |
| Other designations | |
| Database references | |
| SIMBAD | The system |
| ABab | |
| A | |
| Bab | |
| GJ 643 | |
| C (vB 8) | |
| vB 8B (artifact) | |
V1054 Ophiuchi/Gliese 643 has the largest number of stars of all star systems located within 10 pc from Earth.[4] It is also the nearest quintuple star system[3] (the next nearest star systems with at least five stars are GJ 2069 (quintuple)[4] at 41.8 light-years, and Castor[3] (sextuple) at 51.6 light-years), and the only quintuple star system within 10 pc.[4][9]
The system consists of three widely separated parts:
Hierarchy of the system:[3]
|
The brightest and most massive of these five stars is V1054 Ophiuchi A. The close binary subsystem V1054 Ophiuchi B is more massive than V1054 Ophiuchi A, however, its total visual magnitude is 0.1 mag fainter than V1054 Ophiuchi A's visual magnitude.[3]
The total apparent magnitude of the V1054 Ophiuchi A-Bab triple subsystem is 9.02.[3][10]
Despite V1054 Ophiuchi/Gliese 643 consisting of low-mass stars, the system's total mass, due to the large number of components, exceeds the Solar mass,[3] (it is about 1.35 M☉).
Currently, the most accurate distance estimate of V1054 Ophiuchi/Gliese 643 (apart from weighted mean distance, see below) is a trigonometric parallax of V1054 Ophiuchi AB from Gaia EDR3, published in 2020:[2] 153.8754±0.0474 mas, corresponding to a distance of 6.499±0.002 pc, or 21.196±0.007 ly.
Past V1054 Ophiuchi/Gliese 643 distance estimates
V1054 Ophiuchi A-Bab:
| Source | Paper | Parallax, mas | Distance, pc | Distance, ly | Ref. |
|---|---|---|---|---|---|
| Woolley | Woolley et al. 1970 | 156 ± 4 | 6.41 ± 0.17 | 20.9 ± 0.6 | [11] |
| GJ, 3rd version | Gliese & Jahreiß 1991 | 153.9 ± 2.6 | 6.50 ± 0.11 | 21.19 ± 0.36 | [12] |
| YPC, 4th edition | van Altena et al. 1995 | 154.8 ± 0.6 | 6.460 ± 0.025 | 21.07 ± 0.08 | [13] |
| Hipparcos | Perryman 1997 | 174.23 ± 3.90 | 5.74 ± 0.13 | 18.7 ± 0.4 | [10] |
| Soederhjelm | Soederhjelm 1999 | 155.63 ± 1.81 | 6.43 ± 0.08 | 20.96 ± 0.25 | [14] |
| Hipparcos2 | van Leeuwen 2007 | 161.41 ± 5.64 | 6.20 ± 0.22 | 20.21 ± 0.73 | [15] |
Gliese 643:
| Source | Paper | Parallax, mas | Distance, pc | Distance, ly | Ref. |
|---|---|---|---|---|---|
| Woolley | Woolley et al. 1970 | 169 ± 5 | 5.92 ± 0.18 | 19.3 ± 0.6 | [11] |
| GJ, 3rd version | Gliese & Jahreiß 1991 | 171.9 ± 7.3 | 5.82 ± 0.26 | 19.0 ± 0.8 | [12] |
| YPC, 4th edition | van Altena et al. 1995 | 169.8 ± 6.6 | 5.89 ± 0.24 | 19.2 ± 0.8 | [13] |
| Hipparcos | Perryman 1997 | 153.96 ± 4.04 | 6.50 ± 0.18 | 21.2 ± 0.6 | [10] |
| Hipparcos2 | van Leeuwen 2007 | 148.92 ± 4.00 | 6.72 ± 0.19 | 21.9 ± 0.6 | [15] |
V1054 Ophiuchi C (vB 8):
| Source | Paper | Parallax, mas | Distance, pc | Distance, ly | Ref. |
|---|---|---|---|---|---|
| CTIOPI 1.5 m | TSN 14 (Costa et al. 2005) | 155.43 ± 1.33 | 6.43 ± 0.06 | 20.98 ± 0.18 | [16] |
 | This section needs to be updated. The reason given is: The system has parallaxes from Gaia now. (December 2021) |
Weighted mean parallax,[17] considering YPC (V1054 Ophiuchi A-Bab and Gliese 643), Hipparcos (Soederhjelm — V1054 Ophiuchi A-Bab and van Leeuwen — Gliese 643) and CTIOPI (V1054 Ophiuchi C) data, is 154.96 ± 0.52 mas,[18] corresponding to a distance 6.453 ± 0.022 pc, or 21.05 ± 0.07 ly.
V1054 Ophiuchi A-Bab is a close spectroscopic triple subsystem, consisting of the brighter component V1054 Ophiuchi A and the more massive binary subsystem V1054 Ophiuchi Bab, orbiting each other with a period of 627 days,[4][3] or 1.72 years.[3] V1054 Ophiuchi Bab components are orbiting each other with a period of 2.9655 days.[4][3] Both outer and inner orbits are nearly circular and, probably, coplanar[4][3] (in keeping with a general tendency of close triple systems).[4]
V1054 Ophiuchi A-Bab pair is also visually resolved (for nearly 50 years it was the shortest-period resolved by visual means binary, since its binarity was discovered by G. P. Kuiper in 1934),[3] whereas V1054 Ophiuchi Ba-Bb pair is still unresolved).[4][3][note 6]
The projected separation of Gliese 643 from V1054 Ophiuchi A-Bab is 72 arcsec,[4] corresponding at 21.05 light-years to 465 a.u.
vB 8 is the smallest, faintest, and most separated component of the V1054 Ophiuchi system. The projected separation of the red dwarf from the primary triple system is about 220 arcsec,[4][3] corresponding at 21.05 light-years to 1420 a.u. Since it is only three times larger than the projected separation between Gliese 643 and V1054 Ophiuchi A-Bab, and such a small ratio should render the triple system dynamically unstable, it was suggested[3] that the real separation of V1054 Ophiuchi C from V1054 Ophiuchi A-Bab is much larger, at least by a factor of two,[3] i. e. at least 2840 a.u.
In 1984, the apparent detection of an infrared source near vB 8 suggested it had a low mass companion. The low mass of this candidate led to speculation that it may be a brown dwarf; the first such to be detected. This discovery was later found to be spurious, but it produced much interest in this class of astronomical object.[19]
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