Astronomy:Gliese 867

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Short description: Star system in the constellation Aquarius
Gliese 867
Observation data
{{#ifeq:J2000|J2000.0 (ICRS)|Epoch J2000.0      Equinox J2000.0 (ICRS)| [[History:Epoch|Epoch J2000]]      [[Astronomy:Equinox (celestial coordinates)|Equinox J2000}}
Constellation Aquarius[1]
A
Right ascension  22h 38m 45.57462s[2]
Declination −20° 37′ 16.0874″[2]
Apparent magnitude (V) 9.08[3]
B
Right ascension  22h 38m 45.28128s[4]
Declination −20° 36′ 51.8102″[4]
Apparent magnitude (V) 11.49[5]
Characteristics
A
Evolutionary stage main sequence
Spectral type M2.0V[6]
Variable type UV Cet+BY Dra[7]
B
Evolutionary stage main sequence
Spectral type M3.5V[6]
Variable type UV Cet+BY Dra[8]
Astrometry
A
Radial velocity (Rv)−8.70±0.69[9] km/s
Proper motion (μ) RA: +449.207[2] mas/yr
Dec.: −79.046[2] mas/yr
Parallax (π)112.3859 ± 0.0555[2] mas
Distance29.02 ± 0.01 ly
(8.898 ± 0.004 pc)
Absolute magnitude (MV)9.39[3]
B
Radial velocity (Rv)−5.95±3.96[4] km/s
Proper motion (μ) RA: +424.590 mas/yr
Dec.: −66.983 mas/yr
Parallax (π)112.9867 ± 0.0387[4] mas
Distance28.867 ± 0.010 ly
(8.851 ± 0.003 pc)
Orbit[10]
PrimaryA
CompanionC
Period (P)4.0831962(29) d
Semi-major axis (a)0.005607±0.000036″
Eccentricity (e)0.00520±0.00047
Inclination (i)51.95±0.42°
Longitude of the node (Ω)111.64±0.22°
Periastron epoch (T)2437145.575±0.037 JD
Argument of periastron (ω)
(secondary)		307.5±3.0°
Semi-amplitude (K1)
(primary)		46.138±0.011 km/s
Semi-amplitude (K2)
(secondary)		58.275±0.023 km/s
Orbit[6]
PrimaryB
CompanionD
Period (P)1.795±0.017 d
Eccentricity (e)0 (assumed)
Periastron epoch (T)2456160.5611±0.0268 JD
Semi-amplitude (K1)
(primary)		21.4±0.5 km/s
Details
A
Mass0.5503±0.0095[10] M☉
Radius0.56[10] R☉
Temperature3416[11] K
Metallicity [Fe/H]0.08[11] dex
Rotation4.083 d[10][lower-alpha 1]
Rotational velocity (v sin i)5.4±0.6[10] km/s
C
Mass0.4357±0.0075[10] M☉
Radius0.45[10] R☉
Rotation4.083 d[10][lower-alpha 1]
Rotational velocity (v sin i)4.4±0.6[10] km/s
B
Mass0.29±0.06[6] M☉
D
Mass≥0.056±0.007[6] M☉
Other designations
BD−21 6267, GJ 867, CCDM J22388-2037AB
A: FK Aqr, CPD−21 8162, HD 214479, HIP 111802, SAO 191294, LTT 9128, NLTT 54421[9]
B: FL Aqr, L 717-22, LP 876-81, LTT 9127, NLTT 54420[5]
Database references
SIMBADA
B

Gliese 867 is a quadruple star system located 29 light-years (8.9 parsecs) away in the constellation Aquarius. It is composed of two binary sub-systems, Gliese 867 A & B, also known by their variable star designations FK Aquarii and FL Aquarii. Gliese 867 is the third-nearest quadruple system, after Gliese 570 and Mu Herculis,[12] and the nearest such system where the primary star is a red dwarf.[6] There are two closer quintuple systems, V1054 Ophiuchi and Xi Ursae Majoris, the former composed entirely of red dwarfs.[12]

System

GJ 867 A (FK Aqr A)
Period = 4.1 d
GJ 867 C (FK Aqr B)
Sep = 216 au
GJ 867 B (FL Aqr A)
Period = 1.8 d
GJ 867 D (FL Aqr B)

Hierarchy of orbits in the Gliese 867 system

Gliese 867 A & B are separated by 24.5 arcseconds, corresponding to a projected distance of 216 AU. Both are spectroscopic binaries.[6] Gliese 867 A & B are both flare stars and BY Draconis variables.[7][8] They have been known to be flare stars since 1978.[13]

Gliese 867 A (FK Aquarii)

A light curve for FK Aquarii, plotted from TESS data.[14] The binary's orbital period is marked in red. The inset plot, adapted from Byrne et al. (1990),[15] shows a flare.

Gliese 867 A, also known as FK Aquarii, is a close binary orbiting every 4.1 days. The companion star is also called Gliese 867 C.[6] Both stars are red dwarfs around half the mass of the Sun.[10] The system has been known to be a spectroscopic binary since 1965, at that time referred to by its Durchmusterung designation BD−21°6267A.[16] It has also been characterized by astrometry from the Gaia space telescope.[17]

Both stars are magnetically active, and have strong dipolar magnetic fields resembling those found in lower-mass, fully convective red dwarfs. The primary star is the most massive red dwarf known to host this type of magnetic field as of 2024.[10]

Gliese 867 B (FL Aquarii)

A light curve showing flares on FL Aquarii, adapted from Doyle et al. (1986)[18]

Gliese 867 B, also known as FL Aquarii, is a close binary orbiting every 1.8 days. It was found to be a spectrosopic binary in 2014. The primary star is a red dwarf, while the companion, Gliese 867 D, has a minimum mass of only 61±7 Jupiter masses, and so may be a brown dwarf.[6]

See also

Notes

  1. ↑ 1.0 1.1 The two stars are assumed to be in synchronous rotation, so the rotation period is the same as the orbital period.

References

  1. ↑ "Finding the constellation which contains given sky coordinates". 2 August 2008. http://djm.cc/constellation.html. 
  2. ↑ 2.0 2.1 2.2 2.3 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  3. ↑ 3.0 3.1 Koen, C. et al. (April 2010). "UBV(RI)C JHK observations of Hipparcos-selected nearby stars". Monthly Notices of the Royal Astronomical Society 403 (4): 1949–1968. doi:10.1111/j.1365-2966.2009.16182.x. Bibcode: 2010MNRAS.403.1949K. 
  4. ↑ 4.0 4.1 4.2 4.3 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  5. ↑ 5.0 5.1 "V* FL Aqr". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=V%2A+FL+Aqr. 
  6. ↑ 6.0 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 Davison, Cassy L. et al. (February 2014). "The Closest M-dwarf Quadruple System to the Sun". The Astronomical Journal 147 (2): 26. doi:10.1088/0004-6256/147/2/26. Bibcode: 2014AJ....147...26D. 
  7. ↑ 7.0 7.1 "FK Aqr". General Catalog of Variable Stars - VizieR. https://vizier.cds.unistra.fr/viz-bin/VizieR-S?V*%20FK%20Aqr. 
  8. ↑ 8.0 8.1 "FL Aqr". General Catalog of Variable Stars - VizieR. https://vizier.cds.unistra.fr/viz-bin/VizieR-S?V*%20FL%20Aqr. 
  9. ↑ 9.0 9.1 "V* FK Aqr". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=V%2A+FK+Aqr. 
  10. ↑ 10.00 10.01 10.02 10.03 10.04 10.05 10.06 10.07 10.08 10.09 10.10 Tsvetkova, S. et al. (February 2024). "The large-scale magnetic field of the M dwarf double-line spectroscopic binary FK Aqr". Astronomy & Astrophysics 682: A77. doi:10.1051/0004-6361/202347604. Bibcode: 2024A&A...682A..77T. 
  11. ↑ 11.0 11.1 Houdebine, E. R. (April 2010). "Observation and modelling of main-sequence star chromospheres - X. Radiative budgets on Gl 867A and AU Mic (dM1e), and a two-component model chromosphere for Gl 205 (dM1)". Monthly Notices of the Royal Astronomical Society 403 (4): 2157–2166. doi:10.1111/j.1365-2966.2010.16267.x. Bibcode: 2010MNRAS.403.2157H. 
  12. ↑ 12.0 12.1 Reylé, Céline; Jardine, Kevin; Fouqué, Pascal; Caballero, Jose A.; Smart, Richard L.; Sozzetti, Alessandro (30 April 2021). "The 10 parsec sample in the Gaia era". Astronomy & Astrophysics 650: A201. doi:10.1051/0004-6361/202140985. Bibcode: 2021A&A...650A.201R.  Data available at https://gruze.org/10pc/
  13. ↑ Byrne, P. Brendan (April 1978). "Gliese 867 - a New Flare-Star System". Information Bulletin on Variable Stars 1407 (1). Bibcode: 1978IBVS.1407....1B. 
  14. ↑ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. https://mast.stsci.edu/portal/Mashup/Clients/Mast/Portal.html. 
  15. ↑ Byrne, P. B.; Butler, C. J.; Lyons, M. A. (September 1990). "Activity in late-type stars. VI. Optical photometry and UV spectroscopy of the active dMe star, FK Aquarii in late 1983". Astronomy and Astrophysics 236: 455–460. Bibcode: 1990A&A...236..455B. https://articles.adsabs.harvard.edu/pdf/1990A%26A...236..455B. Retrieved 14 April 2025. 
  16. ↑ Herbig, G. H.; Moorhead, J. M. (February 1965). "BD-21°6267A: a New dMe Double-Line Spectroscopic Binary.". Astrophysical Journal 141: 649. doi:10.1086/148150. Bibcode: 1965ApJ...141..649H. 
  17. ↑ Reylé, Céline; Jardine, Kevin; Fouqué, Pascal; Caballero, Jose A.; Smart, Richard L.; Sozzetti, Alessandro (6 February 2023). "The 10 parsec sample in the Gaia era: First update". The 21st Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun. doi:10.5281/zenodo.7576096. Bibcode: 2022csss.confE.218R. 
  18. ↑ Doyle, J. G.; Byrne, P. B.; Butler, C. J. (February 1986). "Flare activity and BY-Draconis-type variability on the late-type dMe star Gliese 867 B". Astronomy and Astrophysics 156: 283–288. Bibcode: 1986A&A...156..283D. https://articles.adsabs.harvard.edu/pdf/1986A%26A...156..283D. Retrieved 14 April 2025. 

Further reading



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