41 G. Arae

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41 G. Arae
Observation data
Epoch J2000      Equinox J2000
Constellation Ara
Right ascension 17h 19m 03.83574s[1]
Declination −46° 38′ 10.4467″[1]
Apparent magnitude (V) 5.48[2] (5.61 / 8.88)[3]
Spectral type G8V + M0V[4]
U−B color index +0.38[5]
B−V color index +0.80[6]
R−I color index +0.41[6]
Radial velocity (Rv) 25.3 ± 0.1[7] km/s
Proper motion (μ) RA: 1037.56[1] mas/yr
Dec.: 108.99[1] mas/yr
Parallax (π) 113.61 ± 0.69[1] mas
Distance 28.7 ± 0.2 ly
(8.80 ± 0.05 pc)
Absolute magnitude (MV) 5.74[8]
Companion 41 G. Ara B
Period (P) 953 yr
Semi-major axis (a) 13.341″
Eccentricity (e) 0.825
Inclination (i) 40.5°
Longitude of the node (Ω) 137.3°
Periastron epoch (T) 1907.5
Argument of periastron (ω)
41 G. Ara A
Mass 0.810[9] M
Radius 0.79[9] R
Luminosity 0.42[citation needed] L
Surface gravity (log g) 4.5[6] cgs
Temperature 5,305[6] K
Metallicity [Fe/H] −0.35[6] dex
Rotational velocity (v sin i) 4.5[10] km/s
Age 5.5–6.3[11] Gyr
41 G. Ara B
Mass 0.52[4] M
Radius 0.650[4] R
Other designations
41 G. Arae, CD-46° 11370, GJ 666, HD 156274, HIP 84720, HR 6416, LHS 444, LTT 6886, SAO 227816, LPM 636, LFT 1334.
Database references
SIMBAD 41 G. Ara
41 G. Ara A
41 G. Ara B
ARICNS 41 G. Ara A
41 G. Ara B

41 G. Arae (abbreviated to 41 G. Ara), also known as GJ 666, is a binary star system in the constellation Ara. Although often called just 41 Arae, it is more accurate to call it 41 G. Arae, as the number 41 is the Gould designation (Flamsteed only covered the northern hemisphere).

The primary star in this system is a G-type main sequence star with a stellar classification of G8V. It has about 81% of the mass of the Sun, and 79% of the Sun's radius.[9] The fainter member of the pair, a red dwarf,[4] has a peculiar spectrum that shows a deficiency in elements with a higher atomic number than Helium. No planetary companions have been detected in orbit around these stars,[12] but the fainter star may itself be a spectroscopic binary.[13]

The two stars share a highly elliptical orbit that takes several centuries to complete. The estimates of the period range from 693 to 2,200 years,[14] and the average separation of the two stars is about 210 AUs (or 210 times the average distance between the Earth and the Sun).

This system has a relatively high proper motion, moving over a second of arc across the sky each year. The space velocity components of this system are [U, V, W] = [+38, +30, −19] km/s.[6] The stars in this system show low chromospheric activity, and have a net space velocity of 52 km/s relative to the Sun. This, in combination with their low metallicity, shows that the pair belongs to the old disk population.[6]

See also[edit]


  1. ^ a b c d e van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752Freely accessible, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357 
  2. ^ Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237. Bibcode:2002yCat.2237....0D. 
  3. ^ a b "Entry 171903.85-463810.1", Sixth Catalog of Orbits of Visual Binary Stars, United States Naval Observatory, retrieved 2016-06-07. 
  4. ^ a b c d Zakhozhaj, V. A. (1979). "Nearest stars". Vestnik Khar'kovskogo Universiteta. SIMBAD. 190: 52–77. Bibcode:1979VKha..190...52Z. 
  5. ^ Johnson, H. L. (1966). "UBVRIJKL Photometry of the Bright Stars". Communications of the Lunar and Planetary Laboratory. 4: 99. Bibcode:1966CoLPL...4...99J. 
  6. ^ a b c d e f g Perrin, M.-N.; de Strobel, G. Cayrel; Dennefeld, M. (1988), "High S/N detailed spectral analysis of four G and K dwarfs within 10 PC of the sun", Astronomy and Astrophysics, 191 (2): 237–247, Bibcode:1988A&A...191..237P 
  7. ^ Nordström, B.; et al. (May 2004), "The Geneva-Copenhagen survey of the Solar neighbourhood. Ages, metallicities, and kinematic properties of ˜14 000 F and G dwarfs", Astronomy and Astrophysics, 418 (3): 989–1019, arXiv:astro-ph/0405198Freely accessible, Bibcode:2004A&A...418..989N, doi:10.1051/0004-6361:20035959 
  8. ^ Holmberg, J.; et al. (July 2009), "The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics", Astronomy and Astrophysics, 501 (3): 941–947, arXiv:0811.3982Freely accessible, Bibcode:2009A&A...501..941H, doi:10.1051/0004-6361/200811191. 
  9. ^ a b c Takeda, G.; et al. (February 2007) [2006], "Structure and Evolution of Nearby Stars with Planets II. Physical Properties of ~ 1000 Cool Stars from the SPOCS Catalog", The Astrophysical Journal Supplement Series, 168 (2): 297–318, arXiv:astro-ph/0607235Freely accessible, Bibcode:2007ApJS..168..297T, doi:10.1086/509763 
  10. ^ Schröder, C.; Reiners, A.; Schmitt, J. H. M. M. (January 2009), "Ca II HK emission in rapidly rotating stars. Evidence for an onset of the solar-type dynamo", Astronomy and Astrophysics, 493 (3): 1099–1107, Bibcode:2009A&A...493.1099S, doi:10.1051/0004-6361:200810377 
  11. ^ Mamajek, Eric E.; Hillenbrand, Lynne A. (November 2008), "Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics", The Astrophysical Journal, 687 (2): 1264–1293, arXiv:0807.1686Freely accessible, Bibcode:2008ApJ...687.1264M, doi:10.1086/591785 
  12. ^ Santos, N. C.; et al. (July 2005), "Spectroscopic metallicities for planet-host stars: Extending the samples", Astronomy and Astrophysics, 437 (3): 1127–1133, arXiv:astro-ph/0504154Freely accessible, Bibcode:2005A&A...437.1127S, doi:10.1051/0004-6361:20052895 
  13. ^ Jenkins, J. S.; Díaz, M.; Jones, H. R. A.; Butler, R. P.; Tinney, C. G.; O'Toole, S. J.; Carter, B. D.; Wittenmyer, R. A.; Pinfield, D. J. (2015). "The observed distribution of spectroscopic binaries from the Anglo-Australian Planet Search". Monthly Notices of the Royal Astronomical Society. 453 (2): 1439. arXiv:1507.04749Freely accessible. Bibcode:2015MNRAS.453.1439J. doi:10.1093/mnras/stv1596. 
  14. ^ de Mello, G. F. Porto; del Peloso, E. F.; Ghezzi, L. (2006), "Astrobiologically interesting stars within 10 parsecs of the Sun", Astrobiology, 6 (2): 308–331, arXiv:astro-ph/0511180Freely accessible, Bibcode:2006AsBio...6..308P, doi:10.1089/ast.2006.6.308, PMID 16689649 

External links[edit]