V1054 Ophiuchi
Coordinates: 
16h 55m 32.0s, −08° 21′ 30″
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Ophiuchus |
| Right ascension | 16h 55m 32.0s |
| Declination | −08° 21′ 30″ |
| Database references | |
| SIMBAD | The system |
| ABab | |
| A | |
| Bab | |
| GJ 643 | |
| C (vB 8) | |
| vB 8B (artifact) | |
V1054 Ophiuchi, together with the star Gliese 643, is a nearby quintuple star system, located in constellation Ophiuchus at 21.05 light-years. It consists of five stars, all of which are red dwarfs.
Overview
V1054 Ophiuchi/Gliese 643 has the largest number of stars of all star systems, located within 10 pc from Earth.[1] It is also the nearest quintuple star system[2] (the next nearest star systems with at least five stars are GJ 2069 (quintuple)[1] at 41.8 light-years, and Castor[2] (sextuple) at 51.6 light-years), and only quintuple star system within 10 pc.[1][3]
The system consists of three widely separated parts:
- close triple subsystem V1054 Ophiuchi A-Bab (including very close binary subsystem V1054 Ophiuchi Bab)
- Gliese 643
- V1054 Ophiuchi C (vB 8)
Hierarchy of the system is following:[2]
|
System's five components are:
| Star | Mass, M☉ | Spectral class | Absolute magnitude (MV) | Apparent magnitude (V) |
|---|---|---|---|---|
| V1054 Ophiuchi A | 0.4155 ± 0.0057[1] | M3 V[1] | 10.69 ± 0.02[2][note 1] | 9.74[2] |
| V1054 Ophiuchi Ba | 0.3466 ± 0.0047[1] | M4 Ve[note 2] | 11.29 ± 0.05[2][note 1] | 10.34[2] |
| V1054 Ophiuchi Bb | 0.3143 ± 0.0040[1] | M4 Ve[note 2] | 11.79 ± 0.05[2][note 1] | 10.84[2] |
| Gliese 643 | 0.19[2] | M3.5 V[1] | 12.69[2] | 11.74[2] |
| V1054 Ophiuchi C | 0.08[2] | M7.0 V[2] | 17.75[2] | 16.80[2] |
The brightest and most massive of this five stars is V1054 Ophiuchi A. 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.[2]
Total apparent magnitude of V1054 Ophiuchi A-Bab triple subsystem is 9.02.[2][4]
Despite V1054 Ophiuchi/Gliese 643 consists of small low-mass stars, system's total mass, due large number of components, exceeds Solar mass,[2] (it is about 1.35 M☉).
Distance
Currently, the most accurate distance estimate of V1054 Ophiuchi/Gliese 643 (apart from weighted mean distance, see below) is trigonometric parallax of V1054 Ophiuchi AB from YPC (Yale Parallax Catalog), 4th edition, published in 1995 (van Altena, Lee & Hoffleit):[5] 154.8 ± 0.6 mas, corresponding to a distance 6.460 ± 0.025 pc, or 21.07 ± 0.08 ly.
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 | [6] |
| GJ, 3rd version | Gliese & Jahreiß 1991 | 153.9 ± 2.6 | 6.50 ± 0.11 | 21.19 ± 0.36 | [7] |
| YPC, 4th edition | van Altena et al. 1995 | 154.8 ± 0.6 | 6.460 ± 0.025 | 21.07 ± 0.08 | [5] |
| Hipparcos | Perryman 1997 | 174.23 ± 3.90 | 5.74 ± 0.13 | 18.7 ± 0.4 | [4] |
| Soederhjelm | Soederhjelm 1999 | 155.63 ± 1.81 | 6.43 ± 0.08 | 20.96 ± 0.25 | [8] |
| Hipparcos2 | van Leeuwen 2007 | 161.41 ± 5.64 | 6.20 ± 0.22 | 20.21 ± 0.73 | [9] |
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 | [6] |
| GJ, 3rd version | Gliese & Jahreiß 1991 | 171.9 ± 7.3 | 5.82 ± 0.26 | 19.0 ± 0.8 | [7] |
| YPC, 4th edition | van Altena et al. 1995 | 169.8 ± 6.6 | 5.89 ± 0.24 | 19.2 ± 0.8 | [5] |
| Hipparcos | Perryman 1997 | 153.96 ± 4.04 | 6.50 ± 0.18 | 21.2 ± 0.6 | [4] |
| Hipparcos2 | van Leeuwen 2007 | 148.92 ± 4.00 | 6.72 ± 0.19 | 21.9 ± 0.6 | [9] |
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 | [10] |
The most accurate estimate is marked in bold.
Weighted mean distance
Weighted mean parallax,[11] 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,[12] corresponding to a distance 6.453 ± 0.022 pc, or 21.05 ± 0.07 ly.
V1054 Ophiuchi A-Bab (inner triple subsystem)
V1054 Ophiuchi A-Bab is a close spectroscopic triple subsystem, consisting of brighter component V1054 Ophiuchi A and more massive binary subsystem V1054 Ophiuchi Bab, orbiting each other with period 627 days,[1][2] or 1.72 years.[2] V1054 Ophiuchi Bab components are orbiting each other with period 2.9655 days.[1][2] Both outer and inner orbits are nearly circular and, probably, coplanar[1][2] (in keeping with a general tendency of close triple systems).[1]
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),[2] whereas V1054 Ophiuchi Ba-Bb pair is still unresolved).[1][2][note 3]
Outer orbit (V1054 Ophiuchi A - V1054 Ophiuchi Bab):
| Period P (yr) | 1.717267 ± 0.000039[2] |
| Period P (days) | 627.0 ± 0.2,[1] 627.232 ± 0.014[2] |
| Semi-major axis a, arcsec | 0.2273 ± 0.0004,[1] 0.2256 ± 0.0011[2] |
| Semi-major axis a, a.u. | 1.46683,[1][note 4] 1.45586[2][note 4] |
| Eccentricity e | 0.042 ± 0.001,[1] 0.0433 ± 0.0018[2] |
| Inclination i, ° | 160.3 ± 0.1,[1] 163.1 ± 1.6[2] |
| Longitude of the periastron ω, ° | 306.0 ± 1.5,[1] 115.6 ± 5.1[2] |
| Position angle of the ascending node Ω, ° | -10.2 ± 0.2,[1] 163.2 ± 3.1[2] |
| Time of periastron passage T0 | MJD 53943. ± 3.,[1] 1988.143 ± 0.011[2] |
The most accurate estimates are marked in bold.
Inner orbit (V1054 Ophiuchi Ba - V1054 Ophiuchi Bb):
| Period P (days) | 2.965509 ± 0.000006,[1] 2.965522 ± 0.000014[2] |
| Semi-major axis a, arcsec | 0.00687[note 5] |
| Semi-major axis a, a.u. | 0.04432[note 6] |
| Eccentricity e | 0.0209 ± 0.0008,[1] 0.026 ± 0.007[2] |
| Inclination i, ° | 164.18 ± 0.08,[1] 16.3 ± 0.3 or 163.7 ± 0.3[2] |
| Longitude of the periastron ω, ° | 150.0 ± 3.0,[1] 166 ± 16[2] |
| Position angle of the ascending node Ω, ° | |
| Time of periastron passage T0 | MJD 50919.48 ± 0.03,[1] HJD 2447337.3 ± 0.14[2] |
The most accurate estimates are marked in bold.
Distant components
Gliese 643
The projected separation of Gliese 643 from V1054 Ophiuchi A-Bab is 72 arcsec,[1] corresponding at 21.05 light-years to 465 a.u.
V1054 Ophiuchi C (vB 8)
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,[1][2] corresponding at 21.05 light-years to 1420 a.u. Since it is only three times larger than projected separation between Gliese 643 and V1054 Ophiuchi A-Bab, and such a small ratio should render triple system dynamically unstable, it was suggested,[2] that real separation of V1054 Ophiuchi C from V1054 Ophiuchi A-Bab is much larger, at least by factor two,[2] 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.[13]
Notes
- 1 2 3 From apparent magnitude and parallax.
- 1 2 Referred to entire V1054 Ophiuchi Bab subsystem.
- ↑ At least it was not resolved by 2001.
- 1 2 Assuming weighted mean parallax 154.96 mas.
- ↑ From masses, period and parallax.
- ↑ From masses and period. According to Mazeh et al. 2001, of order of 0.05 a. u.
References
- 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 Ségransan, D.; Delfosse, X.; Forveille, T.; Beuzit, J.-L.; Udry, S.; Perrier, C.; Mayor, M. (2000). "Accurate masses of very low mass stars. III. 16 new or improved masses". Astronomy and Astrophysics. 364: 665–673. Bibcode:2000A&A...364..665S. arXiv:astro-ph/0010585
. - 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 Mazeh, Tsevi; Latham, David W.; Goldberg, Elad; Torres, Guillermo; Stefanik, Robert P.; Henry, Todd J.; Zucker, Shay; Gnat, Orly; Ofek, Eran O. (2001). "Studies of multiple stellar systems - IV. The triple-lined spectroscopic system V1054 Ophiuchi". Monthly Notices of the Royal Astronomical Society. 325: 343–357. Bibcode:2001MNRAS.325..343M. arXiv:astro-ph/0102451 . doi:10.1046/j.1365-8711.2001.04419.x.
- ↑ RECONS CENSUS OF OBJECTS NEARER THAN 10 PARSECS
- 1 2 3 Vizier, The Hipparcos and Tycho Catalogues (ESA 1997)
- 1 2 3 VizieR, Yale Trigonometric Parallaxes, Fourth Edition (van Altena+ 1995)
- 1 2 Vizier, Stars within 25 pc of the Sun (Woolley+ 1970)
- 1 2 Vizier, Nearby Stars, Preliminary 3rd Version (Gliese+ 1991)
- ↑ Vizier, Visual binary orbits and masses (Soederhjelm 1999)
- 1 2 Vizier, Hipparcos, the New Reduction (van Leeuwen 2007)
- ↑ Costa, Edgardo; Méndez, René A.; Jao, W.-C.; Henry, Todd J.; Subasavage, John P.; Brown, Misty A.; Ianna, Philip A.; Bartlett, Jennifer (2005). "The Solar Neighborhood. XIV. Parallaxes from the Cerro Tololo Inter-American Observatory Parallax Investigation-First Results from the 1.5 m Telescope Program". The Astronomical Journal. 130: 337–349. Bibcode:2005AJ....130..337C. doi:10.1086/430473.
- ↑ DENSE Project. 25 pc White Dwarf Sample (see formulae below)
- ↑ THE ONE HUNDRED NEAREST STAR SYSTEMS brought to you by RECONS (Research Consortium On Nearby Stars)
- ↑ Reid, Neill I.; Hawley, Suzanne L., New Light on Dark Stars: Red Dwarfs, Low-Mass Stars, Brown Dwarfs, Astronomy and Planetary Sciences, Springer Science & Business Media, 2013, p. 344, ISBN 1447136632.