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24 Comae Berenices

24 Comae Berenices is a triple star system in the northern constellationofComa Berenices. It is visible to the naked eye, with the brightest component being an orange-hued star with an apparent visual magnitude of 5.03.^[2] The system is located at a distance of approximately 269 light-years from the Sun based on parallax, and is drifting further away with radial velocities of 3–5 km/s.^[2]

This system can be resolved in a telescope as a pair of stars with an angular separationof20.2″ along a position angle of 272°, as of 2018.^[11] They share a common motion through space and thus appear to be physically associated,^[12] with a wide projected separationof1,400 AU or greater.^[13] If they are bound in an orbit, the estimated period is approximately 28,000 years.^[6]

The brighter member of this system is an aging giantorbright giant star with a stellar classification of K0II-III.^[3] It has exhausted the supply of hydrogen at its core and expanded to 20^[1] times the girth of the Sun. This is a suspected variable that has been recorded ranging in brightness from magnitude 4.98 down to 5.06.^[14] The star is radiating 173^[1] times the luminosity of the Sun from its swollen photosphere at an effective temperature of 4,688 K.^[1]

The fainter component at magnitude 6.57^[2] is a double-lined spectroscopic binary with an orbital period of 7.33 days and an eccentricity of 0.26.^[12] The primary member of this pair is an A-type main-sequence star with a stellar classification of A9V.^[3] It is a metallic-lined Am star^[15] with 2.2 times the radius of the Sun.^[5] The stars radiate about 16 and 7 times the Sun's luminosity from its photosphere, respectively, at effective temperatures of 7,630 and 7180 K, respectively.^[5] Both have relatively low projected rotational velocity of around 14 km/s,^[5] and it is suspected the rotations of this binary system may be synchronized.^[8] The system is a source for X-ray emission, which is most likely coming from the secondary.^[16]