41 Lyncis

Properties

It is estimated using parallax measurements to be approximately 276 ly from the Sun. The spectrum of this star matches a stellar classification of K0 III, with the luminosity class of III suggesting it is a giant star. This star has about double the mass of the Sun, although a re-evaluation of evolutionary tracks published in 2011 gives a lower estimate of solar masses. It has expanded to 11 times the Sun's radius and is radiating 55 times as much as the Sun from its outer atmosphere at an effective temperature of 4,789 K. This temperature gives it the orange-hued glow of a K-type star.

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 and as far as 28.2 kly. The inclination of this orbit will carry it as much as 1800 ly away from the galactic plane. For this reason, it is uncertain whether this star is a member of the thin disk population.

41 Lyncis is listed in the Washington Double Star Catalog as having two visual companions, the 8th-magnitude F-type subgiant HD 81704 away, and an 11th-magnitude star away. Both are background objects, more distant than 41 Lyncis itself, but the two share a common proper motion and are at the same distance as each other.

Nomenclature

41 Lyncis is the Flamsteed designation. 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 (IAU) 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 NameExoWorlds, a process for giving proper names to certain exoplanets and their host stars. The process involved public nomination and voting for the new names. In December 2015, the IAU announced the winning names were Intercrus for this star and Arkas for its planet. 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.

The International Astronomical Union Working Group on Star Names (WGSN) has approved the proper name Intercrus for 41 Lyncis.

Planetary system

On 19 February 2008 a planet was announced orbiting the star, detected by the radial velocity method. It has a minimum mass 2.7 times that of Jupiter and completes an orbit every 184 days.

A 2023 study of planets around evolved stars, while presenting updated parameters for this planet, found that the radial velocity variations are correlated with stellar activity signals, casting doubt on the planet's existence. Based on this, a 2024 study listed it as one of several doubtful planets around giant stars (along with other named planets around 14 Andromedae and 42 Draconis).

References

References

1. [http://www.iau.org/news/pressreleases/detail/iau1404/ NameExoWorlds: An IAU Worldwide Contest to Name Exoplanets and their Host Stars]. IAU.org. 9 July 2014
2. "NameExoWorlds The Process".
3. [http://www.iau.org/news/pressreleases/detail/iau1514/ Final Results of NameExoWorlds Public Vote Released], International Astronomical Union, 15 December 2015.
4. "NameExoWorlds The Approved Names".
5. {{Cite Gaia DR3. 818464227945910016
6. "IAU Catalog of Star Names".
7. {{cite XHIP. 46471
8. (April 2004). "HD-DM-GC-HR-HIP-Bayer-Flamsteed Cross Index (Kostjuk, 2002)". Institute of Astronomy of Russian Academy of Sciences.
9. (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]].
10. (2008). "Vertical distribution of Galactic disk stars. IV. AMR and AVR from clump giants". Astronomy and Astrophysics.
11. (January 2008). "Rotational and radial velocities for a sample of 761 HIPPARCOS giants and the role of binarity". The Astronomical Journal.
12. "* 41 Lyn".
13. (August 2011). "Planet Engulfment by ~1.5-3 M sun Red Giants". The Astrophysical Journal.
14. (December 21, 2004). "The Colour of Stars". [[Commonwealth Scientific and Industrial Research Organisation]].
15. {{cite DR2
16. (2001). "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog". The Astronomical Journal.
17. {{OED. inter-, crus
18. (1990). "MK classification and photometry of stars used for time and latitude observations at Mizusawa and Washington". Astronomy and Astrophysics Supplement Series.
19. (August 2023). "Revisiting planetary systems in the Okayama Planet Search Program: A new long-period planet, RV astrometry joint analysis, and a multiplicity-metallicity trend around evolved stars". [[Publications of the Astronomical Society of Japan]].
20. (September 2024). "Non-radial oscillations mimicking a brown dwarf orbiting the cluster giant NGC 4349 No. 127". [[Astronomy & Astrophysics]].