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Furuhjelm 46
Observation data; Epoch J2000 Equinox J2000
Constellation	Hercules
Right ascension	17h 12m 07.91s
Declination	+45° 39′ 57.2″
Apparent magnitude (V)	10.02/10.25
Characteristics
Spectral type	M3 + M3.5
Astrometry
Radial velocity (Rv)	–19 ± 5 km/s
Proper motion (μ)	RA: +348.59 ± 5.68 mas/yr ; Dec.: –1624.84 ± 6.80 mas/yr
Parallax (π)	156.66 ± 1.37 mas
Distance	20.8 ± 0.2 ly ; (6.38 ± 0.06 pc)
Orbit
Period (P)	12.9512 ± 0.0096 yr
Semi-major axis (a)	0.7620 ± 0.0015″
Eccentricity (e)	0.7430 ± 0.008
Inclination (i)	149.14 ± 0.25°
Longitude of the node (Ω)	160.0 ± 1.3°
Periastron epoch (T)	1991.032 ± 0.011
Argument of periastron (ω); (secondary)	99.0 ± 1.0°
Details
Temperature	3,272 ± 28 K
Metallicity [Fe/H]	–0.31 ± 0.17 dex
Other designations
	BD+45° 2505, HD 155876, HIP 84140, WDS 17121+5450, KUI 79
	Gl 661 A: LFT 1326, LTT 15095, LHS 433, NLTT 44362
	Gl 661 B: LFT 1327, LTT 15096, LHS 434, NLTT 44363
Database references
SIMBAD	The system
	A
	B
	Furuhjelm 46 Location of Furuhjelm 46 in the constellation Hercules;

Furuhjelm 46, also known as HD 155876 and Gliese 661, is a nearby binary star system, consisting of two very similar red dwarfs, located in the constellation Hercules.

The star's duplicity was discovered by the Dutch astronomer Gerard Kuiper in 1934 in a systematic survey for duplicity of the known stars within about 25 parsecs from the Sun, carried out with the 36-inch telescope of the Lick Observatory.^[5] Furuhjelm 46 is the nearest "true" (i. e. not brown dwarf) star system in Hercules, however, there is brown dwarf in this constellation, located closer: WISE 1741+2553.

References

^ Söderhjelm, Staffan (1999). "HIP 84140". Visual binary orbits and masses post Hipparcos.
^ From the Sixth Catalog of Orbits of Visual Binary Stars, based upon Hartkopf, W. I.; Mason, B. D.; McAlister, H. A. (1996), "Binary star orbits from speckle interferometry. VIII. Orbits of 37 close visual systems", Astronomical Journal, 111: 370–392, Bibcode:1996AJ....111..370H, doi:10.1086/117790
^ Fractional Besselian year.
^ ^a ^b Rojas-Ayala, Bárbara; et al. (April 2012). "Metallicity and Temperature Indicators in M Dwarf K-band Spectra: Testing New and Updated Calibrations with Observations of 133 Solar Neighborhood M Dwarfs" (PDF). The Astrophysical Journal. 748 (2): 93. arXiv:1112.4567. Bibcode:2012ApJ...748...93R. doi:10.1088/0004-637X/748/2/93. S2CID 41902340.
^ Kuiper, Gerard (1934). "Two New Close M-Dwarf Binaries of Large Parallax". Publications of the Astronomical Society of the Pacific. 46 (373): 235. Bibcode:1934PASP...46..235K. doi:10.1086/124479. S2CID 119814250.

External links

Diagram of orbit from U.S.Naval Obs. site Archived 2016-03-03 at the Wayback Machine

[Söderhjelm1999-1] Söderhjelm, Staffan (1999). "HIP 84140". Visual binary orbits and masses post Hipparcos.

[aj111_370-2] From the Sixth Catalog of Orbits of Visual Binary Stars, based upon Hartkopf, W. I.; Mason, B. D.; McAlister, H. A. (1996), "Binary star orbits from speckle interferometry. VIII. Orbits of 37 close visual systems", Astronomical Journal, 111: 370–392, Bibcode:1996AJ....111..370H, doi:10.1086/117790

[3] Fractional Besselian year.

[apj748_2_934-4] Rojas-Ayala, Bárbara; et al. (April 2012). "Metallicity and Temperature Indicators in M Dwarf K-band Spectra: Testing New and Updated Calibrations with Observations of 133 Solar Neighborhood M Dwarfs" (PDF). The Astrophysical Journal. 748 (2): 93. arXiv:1112.4567. Bibcode:2012ApJ...748...93R. doi:10.1088/0004-637X/748/2/93. S2CID 41902340.

[1934PASP_46_235K-5] Kuiper, Gerard (1934). "Two New Close M-Dwarf Binaries of Large Parallax". Publications of the Astronomical Society of the Pacific. 46 (373): 235. Bibcode:1934PASP...46..235K. doi:10.1086/124479. S2CID 119814250.

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