Denebola, or β Leo, is the second brightest star in the constellation Leo, with an apparent magnitude of 2.14. It is the easternmost of a prominent triangle of stars to the east of Regulus, and marks the Lion's tail.
The name Denebola is shortened from the Arabic phrase "danab al-asad", meaning "tail of the lion". On R. A. Proctor's 1871 star chart of the northern hemisphere it was designated Deneb Aleet. To ancient Chinese astronomers, it formed part of the five-star Woo Ti Tsi: the Seat of the Twelve Emperors. In astrology, Denebola was believed to portend misfortune and disgrace.
Properties
Denebola is a white class A3 V main-sequence (hydrogen-fusing) star with a surface temperature of 8500 K. It lies a distance of 36 light years. Denebola is 12 times more luminous than the Sun, and interferometric observations give it a radius 1.73 times the Sun's. It contains 75% more mass than the Sun, which results in its higher overall luminosity, and in a shorter main-sequence lifespan. Denebola is a relatively young star, with an age estimated at less than 400 million years.
Typical of young stars, Denebola has a high rotational velocity, at least 120 km/sec, which results in an oblate shape. Denebola is also a δ Scuti-type variable star that exhibits small brightness fluctuations of 0.025 magnitudes roughly ten times per day. The star shows no evidence for any kind of stellar companion.
Dust Disk and Association
Denebola one of a fairly rare class of stars that (like Vega and β Pic) show a strong infrared excess, indicating a "debris disk" of cool dust in orbit around it. As the planets of our solar system are believed to have formed from such a disk, the dust implies that Denebola might have planets as well, though there is no direct evidence for them. The dust surrounding Denebola has a temperature of about 120 K. Unsuccessful attempts have been made to image the dust disk, implying that the disk contains much less material than that surrounding β Pic (which has been imaged frequently).
Kinematic studies have shown that Denebola is part of a stellar association dubbed the IC 2391 supercluster. All the stars of this group share a roughly common motion through space, although they are not gravitationally bound. This implies that they were born in the same location, and perhaps initially formed an open cluster. Other stars in this association include α Pic, β CMi, and the open cluster IC 2391. In total more than sixty probable members of the group have been identified.
[Adapted from STARS by Jim Kaler, Professor Emeritus of Astronomy, University of Illinois]