The Ancient Egyptians based their calendar on the heliacal rising of this body, which was known to them as Sothis. The existence of this body's dimmer companion, discovered by Alvan Clark, was predicted by Friedrich Bessel using observations of this body's "wobble"; that companion is a white dwarf which forms a (*) binary star system with this star.  This star forms the winter triangle along with Betelgeuse [BEE - tle - juice] and Procyon [PRO - see - on], and it is also the alpha star of the constellation Canis Major. For ten points, name this
The Ancient Egyptians based their calendar on the heliacal rising of this body, which was known to them as Sothis. The existence of this body's dimmer companion, discovered by Alvan Clark, was predicted by Friedrich Bessel using observations of this body's "wobble"; that companion is a white dwarf which forms a (*) binary star system with this star.  This star forms the winter triangle along with Betelgeuse [BEE - tle - juice] and Procyon [PRO - see - on], and it is also the alpha star of the constellation Canis Major. For ten points, name this brightest star in the night sky, sometimes nicknamed the "Dog Star."
The Ancient Egyptians based their calendar on the heliacal rising of this body, which was known to them as Sothis.
{Sirius} A (prompt on {Alpha Canis Major} or {Dog Star} before mention)