RT Carinae

RT Carinae, also known as CD-58 3538, is a red supergiant and a variable star, located 7,000 light years away in the constellation Carina. It is in the Carina Nebula. The average apparent magnitude of +8.55, too faint to be visible to the naked eye.

Characteristics
RT Carinae is a red supergiant with a spectral type of M2+ Iab and has a temperature of 3,660 K. It is over 680 times larger than the Sun and is estimated to be 130,000 times more luminous. It is close to the open cluster Trumpler 15, but is not thought to be a member. It appears to be surrounded by a dusty nebula, possibly material ejected from the star itself.

It is catalogued as an irregular variable star, but a number of possible pulsation periods have been detected. Analysis from observations over 40 years give variations with periods of 201 and 448 days, with other studies suggesting periods of 100 and 1,400 days.