Pi Cassiopeiae
Variable star in the constellation Cassiopeia
From Wikipedia, the free encyclopedia
Pi Cassiopeiae is a close binary star[8] system in the constellation Cassiopeia, near the southern border with Andromeda. Its name is a Bayer designation that is Latinized from π Cassiopeiae, and abbreviated Pi Cas or π Cas. This system is visible to the naked eye as a point of light with a combined apparent visual magnitude of +4.949.[3] Based upon an annual parallax shift of 18.63 mas as seen from Earth,[2] this system is located about 175 light-years (54 pc) 175 light years from the Sun. It is drifting further away with a radial velocity of +13 km/s.[7]
This is a double-lined spectroscopic binary system with an orbital period of nearly two days in a circular orbit.[8] It is classified as a rotating ellipsoidal variable star and its brightness varies by 0.02 magnitudes with a period of 23.57 hours,[6] which equals half of its orbital period. The spectrum matches that of an A-type main-sequence star with a stellar classification of A5 V.[4] The two stars have similar masses and spectra.[5] A star at a projected separation of 1,700 AU has been identified as a possible white dwarf. It is at the same distance as Pi Cassiopeiae and shares a common proper motion. The age of the white dwarf is calculated to be about 500 million years.[13]
Pi Cassiopeiae has been given the spectral class of kA3hF1mA5, indicating an Am star,[14] but this is now considered doubtful.[15]