Sigma Persei
Sigma Persei (Sigma Per, σ Persei, σ Per) is an orange K-type giant star with an apparent magnitude of +4.36. It is approximately 343 light-years from Earth.
Sigma Persei is moving through the Galaxy at a speed of 17.4 km/s relative to the Sun. Its projected Galactic orbit carries it between 24,400 and 43,600 light years from the center of the Galaxy. It came closest to the Sun 5.1 million years ago when it had brightened to magnitude 3.11 from a distance of 202 light years.
In 2014 a planet was reported, Sigma Persei b, with a period of 580 days and a mass approximately 6.5 times that of Jupiter. However, a 2025 study found that the observed radial velocity variations are intrinsic to the star, and not caused by a planetary companion.
Name and etymology
This star, together with δ Per, ψ Per, α Per, γ Per and η Per, has been called the Segment of Perseus.