Furuhjelm 46

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.

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[1] mas
Distance20.8 ± 0.2 ly
(6.38 ± 0.06 pc)
Orbit[2]
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[3]
Argument of periastron (ω)
(secondary)		99.0 ± 1.0°
Details
Temperature3,272 ± 28[4] K
Metallicity [Fe/H]–0.31 ± 0.17[4] 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
SIMBADThe system
A
B

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