CK Carinae

CK Carinae (CK Car / HD 90382 / SAO 238038) is a variable star in the constellation Carina, the keel of Argo Navis. It is a member of the star association Carina OB1-D, at a distance of around or .
Classified as a semiregular variable star, CK Carinae's brightness varies between apparent magnitudes +7.2 and +8.5 with a period of approximately 525 days. It has a Gaia Data Release 2 parallax of , which implies a distance of around , and is thought to be a member of the Carina OB1-D stellar association which is at a distance of about . An analysis of the distances of apparently-nearby OB stars implies a distance of for CK Carinae. It has an MK spectral classification of M3.5 Iab, with the luminosity class indicating an intermediate luminosity supergiant.
CK Carinae is a red supergiant with an effective temperature of 3,550 K. It is one of the largest stars, with a radius 761 to 1,060 times larger than the sun, which means that if it were in the place of the Sun, its surface would reach beyond the asteroid belt, Earth being encompassed within the star. Consequently, CK Carinae is also a luminous star, radiating between 86,000 and 158,000 times as much energy as the sun.