41 Lyncis b

41 Lyncis b (abbreviated 41 Lyn b), also designated HD 81688 b and named Arkas /ˈɑːrkəs/,^[3] is a candidate exoplanet approximately 276 light-years from Earth in the constellation of Ursa Major.

41 Lyncis b / Arkas

Discovery[1]
Discovered by	Sato et al.
Discovery site	Okayama Planet Search Program, Japan
Discovery date	February 19, 2008
Detection method	radial velocity
Designations
Alternative names	Arkas
Orbital characteristics[2]
Semi-major axis	0.648 AU (96.9 million km)
Eccentricity	0.040+0.022 −0.031
Orbital period (sidereal)	183.93±0.09 d
Time of periastron	2454354.4+80.2 −16.9 JD
Semi-amplitude	56.42+1.87 −1.88 m/s
Star	41 Lyncis
Physical characteristics[2]
Mass	≥1.654+0.054 −0.055 MJ

A gas giant with a minimum mass 2.7 times that of Jupiter, it orbits the K-type star 41 Lyncis with an orbital period of 184 days (corresponding to a semi-major axis of 0.81 AU). It was discovered and announced by Bun'ei Sato on February 19, 2008.^[1]

Name

In July 2014, the International Astronomical Union (IAU) launched NameExoWorlds, a process for giving proper names to certain exoplanets and their host stars.^[4] The process involved public nomination and voting for the new names.^[5] In December 2015, the IAU announced the name Arkas for this planet.^[6] The winning name was submitted by the Okayama Astro Club of Japan. Arkas was the son of Callisto (Ursa Major) in Greek mythology.^[7]

Planet challenged

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.^[2] Based on this, a 2024 study listed it as one of several doubtful planets around giant stars (along with the other named planets 14 Andromedae b and 42 Draconis b).^[8]

See also

• 18 Delphini b
• Xi Aquilae b