Planets are candidates, not finds.

Over the past 5 weeks, astronomers have reported the discovery of several planets orbiting stars within 100 light-years of the solar system. (SN: 6/27/98, p. 405).

At a late-June symposium of the International Astronomical Union in Victoria, British Columbia, astronomers working at the European Southern Observatory (ESO) in La Serena, Chile, reported on their hunt for extrasolar planets. They have gathered preliminary evidence of three new candidate planets, noted Martin Kfirster, an ESO astronomer based in Santiago, Chile.

Despite some media accounts that put these candidates on an equal footing with extrasolar planets that had been more definitively reported, this data "looks intriguing ... but fails to pass the necessary statistical significance tests" required for them to be bona fide discoveries, Ktirster told SCIENCE NEWS.

The most compelling of the three candidates, he says, is a planet-orbiting the star HR785, also known as phi2 Pavonis. Ktirster and his colleagues, including William D. Cochran of the University of Texas at Austin, deduce that if an unseen object is tugging on HR785, it would have at least 70 percent of the mass of Jupiter and its orbit would be highly elliptical.

The next-best candidate would have at least twice the mass of Jupiter and orbit the star HR810, also known as Iota Horologii. Variations in the star's brightness mimic the wobble that would be induced by a planet and thus confound analysis, Kfirster says. Far less certain is the hint that a planet with a minimum mass of three-fourths that of Jupiter circles the star HR5568. "With additional data, the [star's wobble] may go away," says Cochran. The researchers have decided to omit that candidate in a written account of their report.