Speculation followed about whether it might be a protoplanetary disk, similar to the solar system before the planets formed. However, this is almost certainly not the case since Beta Pictoris is a main sequence star with an age of less than 20 million years. The dust presently in its disk has a life-time of the order of 100,000 years, and must therefore undergo continuous replenishment (see regenerated disk). Although the disk is unlikely to be the site of planet formation today, it may be that existing planets move within it.1 Support for this idea came with the observation of a gap in the disk, between a radius of 10 and 30 AU (1.5 billion and 4.5 billion kilometers). It has been suggested that the dust-free region may have been cleared by a planet of about 5 Earth-masses moving in a near-circular orbit 20 AU (3 billion km) out from the central star.2, 3 Spectral analysis has revealed red-shifted absorption features which some believe are due to comets falling onto the star's outer atmosphere.4 If this is the case, it is again consistent with the presence of a planetary system since one or more gas giants might be responsible for the infall events.
In 1996, using the Hubble Space Telescope, a small warp was detected in the disk within 80 AU (12 billion km) which, according to one theory, is due to the gravitational influence of a massive planet orbiting at right angles to the disk. In January 1998, came the announcement of a larger warp further out in the disk, some 11 billion km (7 billion miles) from the star. This might be due to a brown dwarf in a wide orbit around Beta Pictoris or the nearby passage of another star.
Related entries formation of planetary systems
Related categories NOTABLE STARS
EXTRASOLAR PLANETS AND SUBSTELLAR OBJECTS
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