Yellowish-white first-magnitude star forming one half of Canis Minor
, the Little Dog. A relatively close neighbour of ours (10.5 light-years away), it is five times as luminous as the Sun and one of the brightest stars in our sky, partially on account of its luminosity and partially on account of its proximity.
It is approaching us at 150 miles a minute. Run for your lives!
In Greek its name translated means "before the dog" because at 40° latitude (not arbitrarily chosen - the location of most of the classical observers and namers of our celestial bodies) it rises about 40 minutes before Sirius, the Dog Star.