27 Cancri is a single star in the zodiac constellation of Cancer, located around 990 light-years away from the Sun. It is visible to the naked eye as a faint, red-hued star with a typical apparent visual magnitude of around 5.56. The star is moving closer to the Earth with a heliocentric radial velocity of −8.3 km/s. It is a member of the Arcturus stream, a group of stars with high proper motion and metal-poor properties thought to be the remnants of a small galaxy consumed by the Milky Way.
The variability of the brightness of 27 Cancri was announced by Joel Stebbins and Charles Morse Huffer in 1928, based on observations made at Washburn Observatory. It was given its variable star designation, BP Cancri, in 1977.
This is an aging red giant with a stellar classification of M3 IIIa, currently on the asymptotic giant branch. It is classified as a semiregular variable star of type SRb and its brightness varies from magnitude 5.41 to 5.75 with a period of 40 days. The star is radiating around 2,455 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 3,574 K.
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