"It looks like we're back to an ugly old planet," says David Gray. Nearly a year ago, the University of Western Ontario astronomer had issued a serious challenge to the existence of the first planet to be found near another sunlike star. But in tomorrow's issue of Nature, Gray and another group of researchers led by Artie Hatzes of the University of Texas, Austin, say they have been unable to reproduce his earlier results: What looked like a planet-killer may have been just a chance alignment of noisy data points.
The disputed planet was announced more than 2 years ago by Didier Queloz, now at the Jet Propulsion Laboratory in Pasadena, California, and Michel Mayor of the Geneva Observatory. They had monitored hundreds of dark absorption spikes carved into the spectrum of the star 51 Pegasi by elements in the star's atmosphere. The observed frequencies shifted up and down by small amounts over a 4.23-day period. Mayor and Queloz inferred that a roughly Jupiter-size planet was whipping around 51 Peg in an orbit much closer than Mercury's around the sun, making the star wobble and shifting the spike frequencies by the Doppler or train-whistle effect.
When Gray monitored a single absorption spike, however, he found that its troughlike shape changed over a 4.23-day period. A simple Doppler shift couldn't cause the distortion, but Gray believed that both the shape changes and the frequency shifts could be due to a slow sloshing of the star's surface gases. But Hatzes and co-workers have now made about 120 measurements of several absorption lines at more than twice Gray's spectral resolution and seen no changes in the line shapes. Neither did Gray when he made further observations, and at least two other groups have similar results they have not yet published.
The dispute has thrown light on the underside of the high-stakes field of planet searches. Astronomers had grumbled privately about the harsh tenor of attacks on Gray's work that appeared on the Web. Gray responded in kind on his own Web site, calling some objections "arguments of ignorance." Tempers have cooled since then, but Hatzes says: "I didn't like to see that. It should have been a more civilized debate."