NOTABLE STARS A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z           HOME ABOUT CATEGORIES SITE MAP COPYRIGHT ADVERTISE CONTACT entire Web this site Acrux (Alpha Crucis) The twelfth brightest star in the sky, the southernmost first magnitude star, and the brightest and southernmost star in Crux. Acrux is a multiple system. A moderate telescope shows two similar B stars separated by 4 arc-seconds. Alpha1 is a B subgiant (visual magnitude 1.4, luminosity 25,000 Lsun, surface temperature 28,000 K). Alpha2, a B dwarf (visual magnitude 2.09, luminosity 16,000 Lsun, temperature 26,000 K). Alpha2 is a 13-Msun single star but Alpha1 is a spectroscopic binary whose 14- and 10-Msun components are separated by about one AU and complete an orbit every 76 days. Alpha1 and Alpha2, with a minimum separation of 430 AU, take at least 1,500 years to circle around each other. Another B subgiant lies 90" away from the triplet but, despite its similar velocity through space, is probably a more distant star that happens to lie along the same line of sight. Visual magnitude 0.77 (combined), 1.40/2.09 Absolute magnitude -4.19/-3.79 Spectral type B0.5IV + B1V Distance 320 light-years (98 pc) Position R.A. 12h 26m 35.9s, Dec. -63° 05' 57" Other designations HR 4730/4731, CD -62°2745, HD 108248/108249, SAO 251904, FK5 462, HIP 60718. Related entry    • brightest stars Related category    • NOTABLE STARS Also on this site: Encyclopedia of Alternative Energy & Sustainable Living Encyclopedia of History Transport Concepts & Designs (partner site) BACK TO TOP