GJ 2069
GJ 2069 is a quintuple star system located away in the constellation Cancer. It appears near the Beehive Cluster in the sky, but it is closer than the cluster and is not a member of it. The system is composed of two sub-systems, GJ 2069 A & B, also known by their variable star designations CU Cancri and CV Cancri; both are binary, and GJ 2069 A has a third companion star, making five stars in total. All five stars are red dwarfs.
According to a 2003 study, the system is likely a member of the Castor Moving Group, with an age of 320 million years, but a 2024 study of the stellar magnetic fields found that the system is likely at least 1 billion years old.
System
Hierarchy of orbits in the GJ 2069 system
GJ 2069 A & B are separated by 12 arcseconds. Both are flare stars.
GJ 2069 A (CU Cancri)
GJ 2069 A, also known as CU Cancri, is a close eclipsing binary orbiting every 2.8 days. Both stars are red dwarfs around 40% the mass of the Sun. It was found to be a binary in 1999, and was the third known M-dwarf eclipsing binary, after CM Draconis and YY Geminorum. The stars appear fainter than other stars of the same mass, likely due to high starspot coverage.GJ 2069 A also has a third companion star at a separation of 0.68 arcseconds, designated GJ 2069 D. It was found in 2001.