V1054 Ophiuchi

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]

V1054 Ophiuchi

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
V1054 Oph, BD−08°4352, GJ 644, HD 152751, HIP 82817, SAO 141439, Wolf 630[7]
Database references
SIMBAD	The system
	ABab
	A
	Bab
	GJ 643
	C (vB 8)
	vB 8B (artifact)

Overview

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:

• 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:^[3]

V1054 Ophiuchi/Gliese 643 V1054 Ophiuchi/Gliese 643 (without V1054 Ophiuchi C) V1054 Ophiuchi A‑Bab V1054 Ophiuchi Bab V1054 Ophiuchi Ba V1054 Ophiuchi Bb V1054 Ophiuchi A Gliese 643 V1054 Ophiuchi C (vB 8)

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_☉).

Distance

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]

Weighted mean distance

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 (inner triple subsystem)

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]}

Distant components

Gliese 643

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.

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,^[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]

Notes

1. Referred to entire V1054 Ophiuchi Bab subsystem.
2. From apparent magnitude and parallax.
3. Assuming weighted mean parallax 154.96 mas.
4. From masses, period and parallax.
5. From masses and period. According to Mazeh et al. 2001, of order of 0.05 a. u.
6. At least it was not resolved by 2001.

References

1. Dal, H. A.; Evren, S. (August 2010). "A New Method for Classifying Flares of UV Ceti Type Stars: Differences Between Slow and Fast Flares". The Astronomical Journal. 140 (2): 483–489. arXiv:1206.5791. Bibcode:2010AJ....140..483D. doi:10.1088/0004-6256/140/2/483. S2CID 119308060. Retrieved 4 February 2022.
2. Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
3. 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 (1): 343–357. arXiv:astro-ph/0102451. Bibcode:2001MNRAS.325..343M. doi:10.1046/j.1365-8711.2001.04419.x. S2CID 16472347.
4. Ségransan, Damien; Delfosse, Xavier; Forveille, Thierry; Beuzit, Jean-Luc; Udry, Stéphane; Perrier, Christian; Mayor, Michel (2000). "Accurate masses of very low mass stars. III. 16 new or improved masses". Astronomy and Astrophysics. 364: 665–673. arXiv:astro-ph/0010585. Bibcode:2000A&A...364..665S.
5. Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
6. Pineda, J. Sebastian; Youngblood, Allison; France, Kevin (September 2021). "The M-dwarf Ultraviolet Spectroscopic Sample. I. Determining Stellar Parameters for Field Stars". The Astrophysical Journal. 918 (1): 23. arXiv:2106.07656. Bibcode:2021ApJ...918...40P. doi:10.3847/1538-4357/ac0aea. S2CID 235435757. 40.
7. "HD 152751". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-03-25.
8. Bubar, Eric J.; King, Jeremy R. (August 2010). "Spectroscopic Abundances and Membership in the Wolf 630 Moving Group". The Astronomical Journal. 140 (2): 293–318. arXiv:1005.1205. Bibcode:2010AJ....140..293B. doi:10.1088/0004-6256/140/2/293. S2CID 118455341.
9. RECONS CENSUS OF OBJECTS NEARER THAN 10 PARSECS
10. Vizier, The Hipparcos and Tycho Catalogues (ESA 1997)
11. Vizier, Stars within 25 pc of the Sun (Woolley+ 1970)
12. Vizier, Nearby Stars, Preliminary 3rd Version (Gliese+ 1991)
13. VizieR, Yale Trigonometric Parallaxes, Fourth Edition (van Altena+ 1995)
14. Vizier, Visual binary orbits and masses (Soederhjelm 1999)
15. Vizier, Hipparcos, the New Reduction (van Leeuwen 2007)
16. 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 (1): 337–349. Bibcode:2005AJ....130..337C. CiteSeerX 10.1.1.573.7563. doi:10.1086/430473. S2CID 12213270.
17. DENSE Project. 25 pc White Dwarf Sample (see formulae below)
18. THE ONE HUNDRED NEAREST STAR SYSTEMS brought to you by RECONS (Research Consortium On Nearby Stars)
19. Reid, Neill I.; Hawley, Suzanne L. (27 November 2013), New Light on Dark Stars: Red Dwarfs, Low-Mass Stars, Brown Dwarfs, Astronomy and Planetary Sciences, Springer Science & Business Media, 2013, p. 344, ISBN 978-1447136637.