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V1054 Ophiuchi

Star system in the constellation Ophiuchus From Wikipedia, the free encyclopedia

V1054 Ophiuchi

V1054 Ophiuchi, together with the star Gliese 643, is a nearby quintuple star system, located in the constellation Ophiuchus at a distance of 21.2 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.[11]

Coordinates: \"Sky [http://www.wikisky.org/?ra=Expression+error:+Unrecognized+punctuation+character+%22{%22.&de=Expression+error:+Unrecognized+punctuation+character+%22{%22.&zoom=6&show_grid=1&show_constellation_lines=1&show_constellation_boundaries=1&show_const_names=1&show_galaxies=1&img_source=IMG_all {{{1}}}h {{{2}}}m {{{3}}}s, {{{4}}}{{{5}}}° {{{6}}}′ {{{7}}}″]","parts":[{"template":{"target":{"wt":"Sky","href":"./Template:Sky"},"params":{"1":{"wt":"16"},"2":{"wt":"55"},"3":{"wt":"32.0"},"4":{"wt":"-"},"5":{"wt":"08"},"6":{"wt":"21"},"7":{"wt":"30"},"8":{"wt":"21.05"}},"i":0}}]}">
Quick Facts Apparent magnitude (V), Characteristics ...
V1054 Ophiuchi
Thumb
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
AB
Right ascension 16h 55m 28.75757s[2]
Declination −08° 20′ 10.7878″[2]
Apparent magnitude (V) 9.74/10.34/10.84[3]
Gliese 643
Right ascension 16h 55m 25.22225s[4]
Declination −08° 19′ 21.2970″[4]
Apparent magnitude (V) 11.74[3]
C (VB 8)
Right ascension 16h 55m 35.25574s[5]
Declination −08° 23′ 40.7531″[5]
Apparent magnitude (V) 16.80[3]
Characteristics
Spectral type M3 V[6] / M4 Ve[note 1] / M3.5 V[6] / M7.0 V[3]
Astrometry
Gliese 643
Radial velocity (Rv)15.20±0.15[4] km/s
Proper motion (μ) RA: −817.580(52) mas/yr[4]
Dec.: −898.595(40) mas/yr[4]
Parallax (π)153.8754±0.0474 mas[4]
Distance21.196 ± 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(63) mas/yr[5]
Dec.: −870.609(44) mas/yr[5]
Parallax (π)153.9659 ± 0.0570 mas[5]
Distance21.184 ± 0.008 ly
(6.495 ± 0.002 pc)
Absolute magnitude (MV)17.75[3]
Orbit[6]
PrimaryV1054 Oph A
CompanionV1054 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[6]
PrimaryV1054 Oph Ba
CompanionV1054 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
AB
Mass0.4155±0.0057 / 0.3466±0.0047 / 0.3143±0.0040[6] M☉
Gliese 643
Mass0.19[3] M☉
C (VB 8)
Mass0.0914+0.0026
−0.0025[7] M☉
Radius0.1214+0.0060
−0.0057[7] R☉
Luminosity0.000645+0.000004
−0.000005[7] L☉
Temperature2,640+65
−64[7] K
Other designations
CCDM J16555-0820
AB: V1054 Oph, BD−08°4352, GJ 644, HD 152751, HIP 82817, SAO 141439, LHS 428, Wolf 630[8]
GJ 643: GJ 643, HIP 82809, LHS 427, Wolf 629[9]
C: GJ 644 C, LHS 429, VB 8[10]
Database references
SIMBADABab
GJ 643
C (vB 8)
Close

Overview

Summarize
Perspective
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[3]

V1054 Ophiuchi/Gliese 643 is the nearest quintuple star system;[3] the next nearest star systems with at least five stars are Xi Ursae Majoris (quintuple, including a brown dwarf)[12] at 28.5 light-years, Castor[3] (sextuple) at 49.2 light-years, and GJ 2069 (quintuple)[6] at 54.3 light-years. V1054 Ophiuchi and Xi Ursae Majoris are the only two quintuple star systems within 10 parsecs.[12]

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)

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][13]

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

Summarize
Perspective

Currently, the most accurate distance estimate of V1054 Ophiuchi/Gliese 643 is a trigonometric parallax of Gliese 643 from Gaia DR3:[4] 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:

More information Source, Paper ...
SourcePaperParallax, masDistance, pcDistance, lyRef.
WoolleyWoolley et al. 1970156 ± 46.41 ± 0.1720.9 ± 0.6[14]
GJ, 3rd versionGliese & Jahreiß 1991153.9 ± 2.66.50 ± 0.1121.19 ± 0.36[15]
YPC, 4th editionvan Altena et al. 1995154.8 ± 0.66.460 ± 0.02521.07 ± 0.08[16]
HipparcosPerryman 1997174.23 ± 3.905.74 ± 0.1318.7 ± 0.4[13]
SoederhjelmSoederhjelm 1999155.63 ± 1.816.43 ± 0.0820.96 ± 0.25[17]
Hipparcos2van Leeuwen 2007161.41 ± 5.646.20 ± 0.2220.21 ± 0.73[2]
Close

Gliese 643:

More information Source, Paper ...
SourcePaperParallax, masDistance, pcDistance, lyRef.
WoolleyWoolley et al. 1970169 ± 55.92 ± 0.1819.3 ± 0.6[14]
GJ, 3rd versionGliese & Jahreiß 1991171.9 ± 7.35.82 ± 0.2619.0 ± 0.8[15]
YPC, 4th editionvan Altena et al. 1995169.8 ± 6.65.89 ± 0.2419.2 ± 0.8[16]
HipparcosPerryman 1997153.96 ± 4.046.50 ± 0.1821.2 ± 0.6[13]
Hipparcos2van Leeuwen 2007148.92 ± 4.006.72 ± 0.1921.9 ± 0.6[2]
Close

V1054 Ophiuchi C (vB 8):

More information Source, Paper ...
SourcePaperParallax, masDistance, pcDistance, lyRef.
CTIOPI 1.5 mTSN 14 (Costa et al. 2005)155.43 ± 1.336.43 ± 0.0620.98 ± 0.18[18]
Close

Weighted mean distance

A weighted mean parallax[19] was calculated by RECONS 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 is 154.96±0.52 mas,[20] corresponding to a distance of 6.453±0.022 pc, or 21.05±0.07 ly. This predates Gaia astrometry of the system.

System

Summarize
Perspective

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,[6][3] or 1.72 years.[3] V1054 Ophiuchi Bab components are orbiting each other with a period of 2.9655 days.[6][3] Both outer and inner orbits are nearly circular and, probably, coplanar[6][3] (in keeping with a general tendency of close triple systems).[6]

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).[6][3][note 6]

Gliese 643

The projected separation of Gliese 643 from V1054 Ophiuchi A-Bab is 72 arcsec,[6] 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,[6][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.[21]

Notes

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

References

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