41 Lyncis
A giant star with a disputed planet, named Intercrus.
41 Lyncis (HD 81688, named Intercrus) is a fifth-magnitude K-type giant star located in the northern constellation of Ursa Major, despite its Flamsteed designation suggesting Lynx. It is notable for hosting an extrasolar planet, 41 Lyncis b (Arkas), whose existence has been called into question by later studies.
- Apparent magnitude
- 5
- Spectral type
- K0 III
- Distance
- 276 light-years (85 parsecs)
- Mass
- 2 solar masses (with a 2011 re-evaluation giving 1.1+0.3−0.2 solar masses)
- Radius
- 11 solar radii
- Luminosity
- 55 solar luminosities
- Effective temperature
- 4,789 K
Lore & Background
41 Lyncis is a giant star of spectral class K0 III, with an estimated mass about double that of the Sun, though a 2011 re-evaluation of evolutionary tracks suggests a lower mass of 1.1+0.3−0.2 solar masses. It has expanded to 11 times the Sun's radius and radiates 55 times the Sun's luminosity from its outer atmosphere at an effective temperature of 4,789 K, giving it an orange hue. Parallax measurements place it approximately 276 light-years from the Sun.
The star follows an orbit through the Milky Way with an eccentricity of 0.21, ranging from 18.5 kly to 28.2 kly from the Galactic Center and reaching up to 1,800 ly from the galactic plane, making its membership in the thin disk population uncertain. It has two visual companions listed in the Washington Double Star Catalog: an 8th-magnitude F-type subgiant (HD 81704) 72″ away and an 11th-magnitude star 84″ away, both background objects more distant than 41 Lyncis itself, though the two share a common proper motion and distance.
In July 2014 the IAU launched the NameExoWorlds process, and in December 2015 the winning names were announced: Intercrus for the star and Arkas for its planet, submitted by the Okayama Astro Club of Japan. Intercrus means 'between the legs' in Latin, referring to the star's position in Ursa Major, while Arkas was the son of Callisto (Ursa Major) in Greek mythology. The IAU Working Group on Star Names has approved the proper name Intercrus.
Reader's Guide
41 Lyncis is significant primarily for its planetary system, though the planet's existence is now disputed. On 19 February 2008 a planet was announced orbiting the star, detected by the radial velocity method, with a minimum mass 2.7 times that of Jupiter and an orbital period of 184 days. However, a 2023 study of planets around evolved stars found that the radial velocity variations correlated with stellar activity signals, casting doubt on the planet's existence. A 2024 study subsequently listed it as one of several doubtful planets around giant stars, alongside planets around 14 Andromedae and 42 Draconis. This uncertainty marks a cautionary tale in exoplanet detection around evolved stars. The star's nomenclature also reflects a historical quirk: despite its Flamsteed designation '41 Lyncis' (genitive for Lynx), the IAU's 1930 boundary revision placed it within Ursa Major. Its two visual companions, though background objects, are noted in the Washington Double Star Catalog. The star's galactic orbit with an eccentricity of 0.21 and its uncertain thin-disk membership add to its astrophysical interest.
Did You Know?
- 41 Lyncis is named Intercrus, meaning 'between the legs' in Latin, referring to its position in Ursa Major.
- A 2023 study found that radial velocity variations for the planet correlate with stellar activity, casting doubt on its existence.
- The star has two visual companions, both background objects, that share a common proper motion and distance.
Frequently Asked Questions
What is 41 Lyncis?
41 Lyncis (HD 81688), given the proper name Intercrus, is a fifth-magnitude K0 III giant star sitting roughly 276 light-years from Earth. It physically resides in Ursa Major even though its Flamsteed number points to the constellation Lynx.
Does 41 Lyncis have a confirmed planet?
An extrasolar world designated 41 Lyncis b (Arkas) was reported in connection with the star, but later studies have cast doubt on whether it truly exists. The planetary companion therefore remains a disputed detection rather than a secure one.
How do 41 Lyncis's size and brightness compare to the Sun?
The star's radius extends to about 11 solar radii and it radiates roughly 55 times the Sun's luminosity. Its mass was originally estimated at 2 solar masses, though a 2011 re-evaluation revised that figure down to approximately 1.1 solar masses.
Why does 41 Lyncis carry a Lynx name if it is in Ursa Major?
The Flamsteed designation '41 Lyncis' was assigned under an older set of constellation boundaries, while modern sky charts place the star in Ursa Major. This kind of mismatch between a star's catalogue name and its current constellation is a well-known quirk of historical stellar nomenclature.
Is 41 Lyncis actually a binary or multiple star system?
It is catalogued as a single K0 III giant with no confirmed stellar companion, so it does not qualify as a true binary or multiple system. Its relevance to a multiple-stars reference comes from the disputed planet Arkas and the naming/constellation oddity rather than from a second star.
More in Binary and Multiple Stars, Part 2 1-24
Spotted an error? Know more?
Reader corrections go straight into our review queue. Suggest an edit · How this site is sourced