PU Aurigae

A faint red star in the constellation of Auriga the Charioteer. PU Aurigae falls directly southward of bright Capella in the sky, and eastward of the triangular formation of stars within Auriga known as the Kids. This position places it near the tip of the broad formation known as the Winter Hexagon, of which Capella marks the northernmost point. PU Aurigae lies at a distance of nearly six hundred light years from the Sun (in terms of luminosity, it is comparable to its neighbouring star Capella, but PU Aurigae is much more distant than Capella, and so appears much fainter in the sky).

This is a red giant star, much later in its lifecycle than the Sun, and has swelled to reach a diameter some ninety times greater than the Sun's. It is a pulsating variable star that follows an irregular pattern, growing brighter and dimming over a periods measured in months. Its magnitude as seen from Earth typically varies between +5.50 and +5.60 (on the very fringes of naked eye visibility), but can reach values as faint as +5.78 at times. This pattern places it among a broad group classified as long-period semiregular variables, giant stars of which Aldebaran in Taurus is the brightest and best-known example.