Gliese 867

Gliese 867

Observation data Epoch J2000        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 mas/yr [2] Dec.: −79.046 mas/yr [2]
Parallax (π)	112.3859±0.0555  mas [2]
Distance	29.02 ± 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 [4] Dec.: −66.983 mas/yr [4]
Parallax (π)	112.9867 ± 0.0387  mas [4]
Distance	28.867 ± 0.010  ly (8.851 ± 0.003  pc)
Orbit [10]
Primary	A
Companion	C
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]
Primary	B
Companion	D
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
Mass	0.5503±0.0095 [10]   M☉
Radius	0.56 [10]   R☉
Temperature	3416 [11]   K
Metallicity [Fe/H]	0.08 [11]   dex
Rotation	4.083  d [10] [a]
Rotational velocity (v sin i)	5.4±0.6 [10]  km/s
C
Mass	0.4357±0.0075 [10]   M☉
Radius	0.45 [10]   R☉
Rotation	4.083  d [10] [a]
Rotational velocity (v sin i)	4.4±0.6 [10]  km/s
B
Mass	0.29±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
SIMBAD	A
	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. The binary's orbital period is marked in red. The inset plot, adapted from Byrne et al. (1990), 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)

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

• EZ Aquarii
• Gliese 876

Notes

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". djm.cc. 2 August 2008.
2. Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv: 2208.00211 . Bibcode:2023A&A...674A...1G. doi: 10.1051/0004-6361/202243940 . S2CID   244398875. Gaia DR3 record for this source at VizieR.
3. Koen, C.; Kilkenny, D.; 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. Bibcode:2010MNRAS.403.1949K. doi: 10.1111/j.1365-2966.2009.16182.x .
4. Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv: 2208.00211 . Bibcode:2023A&A...674A...1G. doi: 10.1051/0004-6361/202243940 . S2CID   244398875. Gaia DR3 record for this source at VizieR.
5. "V* FL Aqr". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 10 April 2025.
6. Davison, Cassy L.; White, R. J.; et al. (February 2014). "The Closest M-dwarf Quadruple System to the Sun". The Astronomical Journal . 147 (2): 26. arXiv: 1310.6761 . Bibcode:2014AJ....147...26D. doi:10.1088/0004-6256/147/2/26.
7. "FK Aqr". General Catalog of Variable Stars - VizieR . Retrieved 10 April 2025.
8. "FL Aqr". General Catalog of Variable Stars - VizieR . Retrieved 10 April 2025.
9. "V* FK Aqr". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 10 April 2025.
10. Tsvetkova, S.; Morin, J.; et al. (February 2024). "The large-scale magnetic field of the M dwarf double-line spectroscopic binary FK Aqr". Astronomy & Astrophysics . 682: A77. arXiv: 2312.04247 . Bibcode:2024A&A...682A..77T. doi:10.1051/0004-6361/202347604.
11. 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. Bibcode:2010MNRAS.403.2157H. doi: 10.1111/j.1365-2966.2010.16267.x .
12. 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. arXiv: 2104.14972 . Bibcode:2021A&A...650A.201R. doi:10.1051/0004-6361/202140985. S2CID   233476431. Data available at https://gruze.org/10pc/ Archived 12 March 2023 at the Wayback Machine
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. Retrieved 14 April 2025.
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 . 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. Bibcode:1965ApJ...141..649H. doi:10.1086/148150.
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. arXiv: 2302.02810 . Bibcode:2022csss.confE.218R. doi:10.5281/zenodo.7576096.
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 . Retrieved 14 April 2025.

Further reading

• Byrne, P. B. (April 1979). "Gliese 867 - a multiple flare star system". Monthly Notices of the Royal Astronomical Society . 187 (2): 153–159. Bibcode:1979MNRAS.187..153B. doi: 10.1093/mnras/187.2.153 .

• Byrne, P. B.; McFarland, J. (November 1980). "Gliese 867 - Further observations of a multiple flare star system". Monthly Notices of the Royal Astronomical Society . 193 (3): 525–532. Bibcode:1980MNRAS.193..525B. doi: 10.1093/mnras/193.3.525 .

• Byrne, P. B.; Black, E.; The; P. S. (November 1987). "Activity in late-type dwarfs. I. Walvaren and Johnson photometry of flares and SPOT variations on GL 867A (= FK Aqr) in 1979". Astronomy and Astrophysics . 186: 261–267. Bibcode:1987A&A...186..261B.

• Byrne, P. B.; Doyle, J. G. (November 1987). "Activity in late-type dwarfs. II. Flares and SPOT variations on GL 867A (=FK Aqr) in 1981". Astronomy and Astrophysics . 186: 268–270. Bibcode:1987A&A...186..268B.

• Agrawal, P. C. (October 1988). "X-ray emission from the flare star binary Gliese 867A". Astronomy and Astrophysics . 204: 235–238. Bibcode:1988A&A...204..235A.

• Pollock, A. M. T.; Tagliaferri, G.; Pallavicini, R. (January 1991). "Quiscent and flaring X-rays from both Gliese 867A and Gliese 867B". Astronomy and Astrophysics . 241: 451–456. Bibcode:1991A&A...241..451P.