T Persei
T Persei is a red supergiant located in the constellation Perseus. It varies in brightness between magnitudes 8.3 and 9.7 and is considered to be a member of the Double Cluster.
T Persei is a member of the Perseus OB1 association around the h and χ Persei open clusters, around 2 degrees north of the centre of the clusters. It is generally treated as an outlying member of the clusters. It lies half a degree away from S Persei, another red supergiant Double Cluster member.
Vojtěch Šafařík discovered that the star is a variable star in 1882. It was listed with its variable star designation, T Persei, in Annie Jump Cannon's 1907 work Second Catalog of Variable Stars. T Per is a semiregular variable star, whose brightness varies from magnitude 8.34 to 9.7 over a period of 2,430 days. Unlike many red supergiants, it does not appear to have a long secondary period. It is relatively inactive for the red supergiant star, with low mass loss rate /year and no detectable dust shell.
The Washington Double Star Catalog lists T Persei as having a 9th magnitude companion away. This is derived from Hipparcos measurements. However, no other sources report a companion.