Alpha Pictoris

At magnitude 3.27, Alpha Pictoris is the brightest star in the modern constellation Pictor, the Easel. Alpha Pictoris has the distinction of being the south pole star of Mercury.

Properties

Alpha Pictoris is a class A7 IV subgiant that shines from a distance of 99 light years. Its average surface temperature measurement is 7950 K, and its total luminosity is 35 suns, with a radius 3.1 times solar. Its mass is between 2.1 and 2.2 suns, and its age is close to a billion years.

Like many stars of its kind, α Pic is a fast rotator, with an equatorial rotation velocity at least 205 km/sec, and a rotation period of less than 18 hours. With fast rotation, no convection, and no magnetic field, α Pic still produces X-rays. These probably come from a hidden, lower-mass companion. Variations in the star's position observed by the Hipparcos satellite suggest the same thing. Yet the companion - if it exists at all - has not been seen or confirmed.

[Adapted from STARS by Jim Kaler, Professor Emeritus of Astronomy, University of Illinois]