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41 Lyncis

Coordinates: Sky map 09h 28m 40s, +45° 36′ 05″
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41 Lyncis or HD 81688
Diagram showing star positions and boundaries of the Ursa Major constellation and its surroundings
Diagram showing star positions and boundaries of the Ursa Major constellation and its surroundings

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]
Characteristics
Spectral type K0 III-IV[3]
U−B color index 0.74
B−V color index 0.983[3]
Astrometry
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 mas[1]
Distance280 ± 9 ly
(86 ± 3 pc)
Absolute magnitude (MV)0.675[3]
Details
Mass2.07+0.14
−0.16[4] M☉
Radius11[5] R☉
Luminosity55[5] L☉
Surface gravity (log g)2.30[3] cgs
Temperature4789[3] K
Metallicity [Fe/H]–0.23[3] dex
Rotational velocity (v sin i)[5] km/s
Age4.07±2.24[3] Gyr
Other designations
Intercrus, BD+46 1509, CCDM J09287+4536, GC 13051, HD 81688, HIP 46471, HR 3743, SAO 42876.[2]
Database references
SIMBADThe star
planet b
Data sources:
Hipparcos Catalogue,
CCDM (2002),
Bright Star Catalogue (5th rev. ed.)

41 Lyncis (abbreviated 41 Lyn), also designated HD 81688 and named Intercrus,[6] is a fifth magnitude star located in the northern constellation of Ursa Major. An extrasolar planet (designated 41 Lyncis b or HD 81688 b, later named Arkas) is thought to be orbiting the star.

Estimated using parallax measurements to be approximately 280 light-years (86 parsecs) from the Sun,[1] it appears to be a single star[7] although flagged as a double star by SIMBAD.[2] 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
−0.2 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.[8]

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]

Nomenclature

41 Lyncis is the Flamsteed designation.[9] Typically, 'Lyncis' is the genitive for a star found in the constellation of Lynx. However, when the constellation boundaries were officially established by the International Astronomical Union in 1930, this star was located within Ursa Major. HD 81688 is the entry in the Henry Draper Catalogue. Following its discovery the planet was designated 41 Lyncis b or alternatively HD 81688 b. In July 2014 the IAU launched a process for giving proper names to certain exoplanets and their host stars.[10] The process involved public nomination and voting for the new names.[11] In December 2015, the IAU announced the winning names were Intercrus for this star and Arkas for its planet.[12]

The winning names were those submitted by the Okayama Astro Club of Japan. Intercrus means "between the legs" in Latin style, referring to the star's position in the constellation Ursa Major. Arkas was the son of Callisto (Ursa Major) in Greek mythology.[13]

In 2016, the IAU organized a Working Group on Star Names (WGSN)[14] to catalog and standardize proper names for stars. In its first bulletin of July 2016,[15] the WGSN explicitly recognized the names of exoplanets and their host stars approved by the Executive Committee Working Group Public Naming of Planets and Planetary Satellites, including the names of stars adopted during the 2015 NameExoWorlds campaign. This star is now so entered in the IAU Catalog of Star Names.[6]

Planetary system

On 19 February 2008 a planet was announced orbiting the star. It has 2.7 times the mass of Jupiter and completes an orbit every 184 days.[16]

The 41 Lyncis planetary system[16]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
b (Arkas) 2.7 MJ 0.81 184.02 ± 0.18 0 (fixed) — —

References

  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. ^ a b "IAU Catalog of Star Names". Retrieved 28 July 2016.
  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.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  8. ^ "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, retrieved 2012-01-16
  9. ^ 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
  10. ^ NameExoWorlds: An IAU Worldwide Contest to Name Exoplanets and their Host Stars. IAU.org. 9 July 2014
  11. ^ NameExoWorlds The Process
  12. ^ Final Results of NameExoWorlds Public Vote Released, International Astronomical Union, 15 December 2015.
  13. ^ NameExoWorlds The Approved Names
  14. ^ "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016.
  15. ^ "Bulletin of the IAU Working Group on Star Names, No. 1" (PDF). Retrieved 28 July 2016.
  16. ^ a b 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
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