 Anultraviolet bandlight curve for a flare on V1054 Ophiuchi, plotted from data published by Dal and Evren (2010)[1] | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Ophiuchus[2] |
| AB | |
| Right ascension | 16h 55m 28.75757s[3] |
| Declination | −08° 20′ 10.7878″[3] |
| Apparent magnitude (V) | 9.74/10.34/10.84[4] |
| Gliese 643 | |
| Right ascension | 16h 55m 25.22225s[5] |
| Declination | −08° 19′ 21.2970″[5] |
| Apparent magnitude (V) | 11.74[4] |
| C (VB 8) | |
| Right ascension | 16h 55m 35.25574s[6] |
| Declination | −08° 23′ 40.7531″[6] |
| Apparent magnitude (V) | 16.80[4] |
| Characteristics | |
| AB | |
| Spectral type | M3 V[7] / M4 Ve[note 1] |
| Gliese 643 | |
| Spectral type | M3.5 V[7] |
| C (VB 8) | |
| Spectral type | M7.0 V[4] |
| Astrometry | |
| AB | |
| Radial velocity (Rv) | 14.89±0.05[8] km/s |
| Proper motion (μ) | RA: −817.84±6.68mas/yr[3] Dec.: −873.53±3.53mas/yr[3] |
| Parallax (π) | 161.41±5.64 mas[3] |
| Distance | 20.2 ± 0.7 ly (6.2 ± 0.2 pc) |
| Absolute magnitude (MV) | 10.23[2] |
| Gliese 643 | |
| Radial velocity (Rv) | 15.20±0.15[5] km/s |
| Proper motion (μ) | RA: −817.580(52)mas/yr[5] Dec.: −898.595(40)mas/yr[5] |
| Parallax (π) | 153.8754±0.0474 mas[5] |
| Distance | 21.196 ± 0.007 ly (6.499 ± 0.002 pc) |
| Absolute magnitude (MV) | 12.60[2] |
| VB 8 | |
| Proper motion (μ) | RA: −813.038(63)mas/yr[6] Dec.: −870.609(44)mas/yr[6] |
| Parallax (π) | 153.9659±0.0570 mas[6] |
| Distance | 21.184 ± 0.008 ly (6.495 ± 0.002 pc) |
| Absolute magnitude (MV) | 17.75[4] |
| Orbit[7] | |
| Primary | V1054 Oph A |
| Companion | V1054 Oph B |
| Period (P) | 1.717267±0.000039[4] yr |
| Semi-major axis (a) | 0.2273±0.0004" (1.46683 AU[note 2]) |
| Eccentricity (e) | 0.042±0.001 |
| Inclination (i) | 160.3±0.1° |
| Longitude of the node (Ω) | −10.2±0.2° |
| Periastronepoch (T) | MJD53943±3 |
| Argument of periastron (ω) (secondary) | 306.0±1.5° |
| Orbit[7] | |
| Primary | V1054 Oph Ba |
| Companion | V1054 Oph Bb |
| Period (P) | 2.965509±0.000006 d |
| Semi-major axis (a) | 0.00687[note 3]" (0.04432 AU[note 4]) |
| Eccentricity (e) | 0.0209±0.0008 |
| Inclination (i) | 164.18±0.08° |
| Periastronepoch (T) | MJD50919.48±0.03 |
| Argument of periastron (ω) (secondary) | 150.0±3.0° |
| Details | |
| AB | |
| Mass | 0.4155±0.0057 /0.3466±0.0047 /0.3143±0.0040[7] M☉ |
| Gliese 643 | |
| Mass | 0.19[4] M☉ |
| C (VB 8) | |
| Mass | 0.0914+0.0026 −0.0025[9] M☉ |
| Radius | 0.1214+0.0060 −0.0057[9] R☉ |
| Luminosity | 0.000645+0.000004 −0.000005[9] L☉ |
| Temperature | 2,640+65 −64[9] K |
| Rotation | 11.19±0.02[10] days |
| Other designations | |
| CCDM J16555-0820 | |
| AB:V1054 Oph,BD−08°4352,GJ 644,HD 152751,HIP 82817,SAO 141439,LHS 428,Wolf 630[11] | |
| GJ 643:GJ 643,HIP 82809,LHS 427,Wolf 629[12] | |
| C:GJ 644 C,LHS 429,VB 8[13] | |
| Database references | |
| SIMBAD | ABab |
| GJ 643 | |
| C (vB 8) | |
V1054 Ophiuchi, together with the starGliese 643, is a nearby quintuple star system, located in the constellationOphiuchus at a distance of 21.2light-years. It consists of five stars, all of which arered dwarfs. The alternative designation of Wolf 630 forms the namesake of amoving group of stars that share a similar motion through space.[14]
| A | |||||||||||||||||
| P = 1.72 yr | |||||||||||||||||
| Ba | |||||||||||||||||
| P = 2.97 d | |||||||||||||||||
| Bb | |||||||||||||||||
| 72″ separation | |||||||||||||||||
| GJ 643 | |||||||||||||||||
| 220″ separation | |||||||||||||||||
| C (VB 8) | |||||||||||||||||
Hierarchy of orbits in the system[4]
V1054 Ophiuchi/Gliese 643 is the nearest quintuple star system;[4] the next nearest star systems with at least five stars areXi Ursae Majoris (quintuple, including a brown dwarf)[15] at 28.5 light-years,Castor[4] (sextuple) at 49.2 light-years, andGJ 2069 (quintuple)[7] at 54.3 light-years. V1054 Ophiuchi and Xi Ursae Majoris are the only two quintuple star systems within 10parsecs.[15]
The system consists of three widely separated parts:
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.[4]
The total apparent magnitude of the V1054 Ophiuchi A-Bab triple subsystem is 9.02.[4][16]
Despite V1054 Ophiuchi/Gliese 643 consisting of low-mass stars, the system's total mass, due to the large number of components, exceeds theSolar mass,[4] about 1.35 M☉.
Currently, the most accurate distance estimate of V1054 Ophiuchi/Gliese 643 is atrigonometric parallax of Gliese 643 fromGaia DR3:[5]153.8754±0.0474mas, corresponding to a distance of6.499±0.002pc, or21.196±0.007ly.
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 | [17] |
| GJ, 3rd version | Gliese & Jahreiß 1991 | 153.9 ± 2.6 | 6.50 ± 0.11 | 21.19 ± 0.36 | [18] |
| YPC, 4th edition | van Altena et al. 1995 | 154.8 ± 0.6 | 6.460 ± 0.025 | 21.07 ± 0.08 | [19] |
| Hipparcos | Perryman 1997 | 174.23 ± 3.90 | 5.74 ± 0.13 | 18.7 ± 0.4 | [16] |
| Soederhjelm | Soederhjelm 1999 | 155.63 ± 1.81 | 6.43 ± 0.08 | 20.96 ± 0.25 | [20] |
| Hipparcos2 | van Leeuwen 2007 | 161.41 ± 5.64 | 6.20 ± 0.22 | 20.21 ± 0.73 | [3] |
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 | [17] |
| GJ, 3rd version | Gliese & Jahreiß 1991 | 171.9 ± 7.3 | 5.82 ± 0.26 | 19.0 ± 0.8 | [18] |
| YPC, 4th edition | van Altena et al. 1995 | 169.8 ± 6.6 | 5.89 ± 0.24 | 19.2 ± 0.8 | [19] |
| Hipparcos | Perryman 1997 | 153.96 ± 4.04 | 6.50 ± 0.18 | 21.2 ± 0.6 | [16] |
| Hipparcos2 | van Leeuwen 2007 | 148.92 ± 4.00 | 6.72 ± 0.19 | 21.9 ± 0.6 | [3] |
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 | [21] |
Aweighted mean parallax[22] was calculated byRECONS in 2012, 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. The value is154.96±0.52 mas,[23] corresponding to a distance of6.453±0.022 pc, or21.05±0.07 ly. This predates Gaia astrometry of the system.
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,[7][4] or 1.72 years.[4] V1054 Ophiuchi Bab components are orbiting each other with a period of 2.9655 days.[7][4] Both outer and inner orbits are nearly circular and, probably, coplanar[7][4] (inkeeping with a general tendency of close triple systems).[7]
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 byG. P. Kuiper in 1934),[4] whereas V1054 Ophiuchi Ba-Bb pair is still unresolved).[7][4][note 5]
The projected separation of Gliese 643 from V1054 Ophiuchi A-Bab is 72arcsec,[7] corresponding at 21.05 light-years to 465AU.
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 220arcsec,[7][4] corresponding at 21.05 light-years to 1420a.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[4] that the real separation of V1054 Ophiuchi C from V1054 Ophiuchi A-Bab is much larger, at least by a factor of two,[4] i. e. at least 2840a.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 abrown 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.[24]
