A main sequence white dwarf star, the brightest in the constellation Aquila (the Eagle). Altair is about 1.7 times the mass of Sol, and 10.8 times as luminous. Altair also has roughly twice the metallicity of Sol - it has more elements heavier than hydrogen. Dust has been detected around Altair, probably a remnant from the cloud of dust and gas that the star was formed from. If it is a remnant from the proto-stellar cloud, it indicates how young this star is. Altair is not believed to have any planets orbiting it. Altair is currently about 16.7 light years (about 158 billion km)away, but the blue shifting tells us that it is travelling toward the solar system at about 26 km/s.
Altair has a very high rotation speed - 210 km/s (131 mi/s), taking only 10.4 hours to rotate once. In comparison, Sol takes about 640 hours to rotate. In 2001 David Ciardi and Gerard van Belle (of NASA’s Jet Propulsion Laboratory) discovered, via the Palomar Testbed Interferometer, that Altair’s high speed rotation has given it an orange-like shape, the equatorial diameter being 14% larger than the polar diameter (distance between the poles). At this time, only Altair is the only star that has been observed to have this feature.
References:
http://www.solstation.com/stars/altair.htm
http://www.jpl.nasa.gov/releases/2001/release_2001_150.html
http://abcnews.go.com/sections/scitech/DailyNews/bulgingstar010727.html
http://www.krysstal.com/brightest.html