Sigma Persei (Sigma Per, σ Persei, σ Per) is an orange K-type

giant In folklore, giants (from Ancient Greek: ''wiktionary:gigas, gigas'', cognate wiktionary:giga-, giga-) are beings of humanoid appearance, but are at times prodigious in size and strength or bear an otherwise notable appearance. The word ''gia ...

star with an

apparent magnitude Apparent magnitude () is a measure of the Irradiance, brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and any extinction (astronomy), ...

of +4.36. It is approximately 343

light-years A light-year, alternatively spelled light year (ly or lyr), is a unit of length used to express astronomical distances and is equal to exactly , which is approximately 9.46 trillion km or 5.88 trillion mi. As defined by the International Astro ...

from

Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...

. 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.Sigma Persei (HIP 16335)
/ref> 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 The radial velocity or line-of-sight velocity of a target with respect to an observer is the rate of change of the vector displacement between the two points. It is formulated as the vector projection of the target-observer relative 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''.

References

{{DEFAULTSORT:Sigma Persei Persei, Sigma Perseus (constellation) K-type giants Persei, 35 016335 1052 021552 BD+47 0843 Suspected variables