41 Lyncis

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41 Lyncis or HD 81688
Diagram showing star positions and boundaries of the Ursa Major constellation and its surroundings
Cercle rouge 100%.svg

Location of 41 Lyncis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Ursa Major
Right ascension 09h 28m 39.98840s[1]
Declination +45° 36′ 05.3344″[1]
Apparent magnitude (V) 5.413[2]
Spectral type K0 III-IV[3]
U−B color index 0.74
B−V color index 0.983[3]
Radial velocity (Rv) +38.44[3] km/s
Proper motion (μ) RA: -7.50[1] mas/yr
Dec.: -128.77[1] mas/yr
Parallax (π) 11.65 ± 0.39[1] mas
Distance 280 ± 9 ly
(86 ± 3 pc)
Absolute magnitude (MV) 0.675[3]
Mass 2.07+0.14
[4] M
Radius 11[5] R
Luminosity 55[5] L
Surface gravity (log g) 2.30[3] cgs
Temperature 4,789[3] K
Metallicity [Fe/H] –0.23[3] dex
Rotational velocity (v sin i) [5] km/s
Age 4.07 ± 2.24[3] Gyr
Other designations
BD+46 1509, CCDM J09287+4536, GC 13051, HD 81688, HIP 46471, HR 3743, SAO 42876.[2]
Database references
Data sources:
Hipparcos Catalogue,
CCDM (2002),
Bright Star Catalogue (5th rev. ed.)

41 Lyncis (also called HD 81688) is the Flamsteed designation[6] for a fifth magnitude star located in the northern circumpolar constellation of Ursa Major. Typically, 'Lyncis' is the genitive for a star found in the constellation Lynx. However, when the constellation boundaries were officially established by the International Astronomical Union in 1930, this star was located within Ursa Major. The distance to this star can be determined using parallax measurements, yielding an estimate of roughly 280 light-years (86 parsecs) away.[1] Although flagged as a double star by SIMBAD,[2] it appears to be a single star.[7] A planetary companion was announced in 2008.[8]

The spectrum of this star matches a stellar classification of K0 III-IV,[3] with the luminosity class of III-IV suggesting it is at an evolutionary stage part way between a subgiant star and a giant star. This star has about double the mass of the Sun, although Kunitomo et al. (2011) give a lower estimate of 1.1+0.3
solar masses.[4] It has expanded to 11 times the Sun's radius and is radiating 55 times as much luminosity as the Sun from its outer atmosphere at an effective temperature of 4,789 K.[5] This heat gives it the orange-hued glow of a K-type star.[9]

This star is following an orbit through the Milky Way with an eccentricity of 0.21. This will take it as close to the Galactic Center as 18.5 kly (5.7 kpc) and as far as 28.2 kly (8.6 kpc). The inclination of this orbit will carry it as much as 1,800 ly (550 pc) away from the galactic plane. For this reason, it is uncertain whether this star is a member of the thin disk population.[3]


On 19 February 2008 a planet was announced orbiting this star. Designated 41 Lyncis b, it has 2.7 times the mass of Jupiter and completes an orbit every 184 days.[8]

The 41 Lyncis planetary system[8]
(in order from star)
Mass Semimajor axis
Orbital period
Eccentricity Inclination Radius
b 2.7 MJ 0.81 184.02 ± 0.18 0 (fixed)


  1. ^ a b c d e f van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357 
  2. ^ a b c "HR 3743 -- Star in double system", SIMBAD Astronomical Object Database (Centre de Données astronomiques de Strasbourg), retrieved 2012-03-25 
  3. ^ a b c d e f g h i j Soubiran, C. et al. (2008), "Vertical distribution of Galactic disk stars. IV. AMR and AVR from clump giants", Astronomy and Astrophysics 480 (1): 91–101, arXiv:0712.1370, Bibcode:2008A&A...480...91S, doi:10.1051/0004-6361:20078788 
  4. ^ a b Kunitomo, M. et al. (August 2011), "Planet Engulfment by ~1.5-3 M sun Red Giants", The Astrophysical Journal 737 (2): 66, arXiv:1106.2251, Bibcode:2011ApJ...737...66K, doi:10.1088/0004-637X/737/2/66 
  5. ^ a b c d Massarotti, Alessandro et al. (January 2008), "Rotational and radial velocities for a sample of 761 HIPPARCOS giants and the role of binarity", The Astronomical Journal 135 (1): 209–231, Bibcode:2008AJ....135..209M, doi:10.1088/0004-6256/135/1/209 
  6. ^ Kostjuk, N. D. (April 2004), "HD-DM-GC-HR-HIP-Bayer-Flamsteed Cross Index (Kostjuk, 2002)", VizieR On-line Data Catalog: IV/27A (Institute of Astronomy of Russian Academy of Sciences), Bibcode:2004yCat.4027....0K 
  7. ^ Eggleton, P. P.; Tokovinin, A. A. (September 2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society 389 (2): 869–879. arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x. 
  8. ^ a b c Sato, Bun'ei et al. (2008), "Planetary Companions around Three Intermediate-Mass G and K Giants: 18 Delphini, ξ Aquilae and HD 81688", Publications of the Astronomical Society of Japan 60 (3): 539–550, arXiv:0802.2590, Bibcode:2008PASJ...60..539S, doi:10.1093/pasj/60.3.539 
  9. ^ "The Colour of Stars", Australia Telescope, Outreach and Education (Commonwealth Scientific and Industrial Research Organisation), December 21, 2004, retrieved 2012-01-16 

External links[edit]

Coordinates: Sky map 09h 28m 40s, +45° 36′ 05″