45 Cancri

45 Cancri, also designated as HD 74721, is a binary star system located approximately 410 light-years away from Earth in the constellation Cancer. The primary star, 45 Cancri A, is a yellow giant star of spectral type G5III. It is significantly larger and more luminous than our Sun, having exhausted the hydrogen fuel in its core and expanded off the main sequence.

The companion star, 45 Cancri B, is a fainter star located at a significant angular separation from 45 Cancri A. Its properties are less well-characterized. The two stars orbit each other with a very long period, likely spanning many centuries or even millennia.

Due to its brightness, 45 Cancri is visible through binoculars or a small telescope. Observations of the system contribute to our understanding of stellar evolution and binary star dynamics. The distance to 45 Cancri has been determined using parallax measurements obtained by space-based observatories like Hipparcos and Gaia.