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A companion star, instead of a planet.
Pan, a specialist in the science of binary, or double, stars, likes to remind people that lone stars like our own sun are a minority in the universe. Most stars are paired with companions; these dual stars spin around in space, like the tips of a propeller blade, in eons-long dances. Some 70 percent of the stars in the universe are joined in this manner, akin to the double suns that hovered over Luke Skywalker's home in the movie Star Wars.
"The heavens are like a human society," says Pan. "Couples are common, singles are rare."
Pan believes at least two of the stars Butler and Marcy say have planets are actually being tugged around by binary companion stars. Using the experimental interferometer telescopes atop Mount Palomar, Pan has been observing the stars 51 Pegasi and tau Bootis over the course of nearly a year, and he believes he has enough evidence to submit a paper to Nature this month that would erase two of Butler and Marcy's planets from the sky.
If Pan's assertion were true, it would explain everything. It would account for Gray's stellar pulsations, the wobbles of Marcy and Butler -- everything. As they spin around in lock step, the competing gravity of binary stars can cause one another's mass of nuclear plasma to billow and slosh in a way similar to how David Gray says 51 Pegasi does. As for the wobbling back and forth that Marcy and Butler observed: Binary stars pull each other around in one of the most dramatic gravitational dances in the known universe.
Pan believes so strongly in his results that he plans to submit his paper to Nature in defiance of the other members of his research team. This is a highly unusual move. Until now, papers he has produced using the Palomar interferometer have also borne the names of Kulkarni, Colavita, and Shao.
Already, Kulkarni, Colavita, and Shao have gone into an astronomer's version of spin mode, working to stem the public relations disaster of NASA-funded astronomers bickering in public.
"We've now decided to have one spokesman at Caltech, which is me, one at the Jet Propulsion Laboratory, which is Mark," says Kulkarni, warming to the task of public relations flack. "At the end of this conversation, you will realize that I haven't told you anything at all."
It is far too early to tell whether there is any substance to Pan's claims that some of the Marcy-Butler planets should be erased. Given that his own research partners challenge his results, he will be hard pressed to win over the jury of independent scholars that Nature uses to judge whether papers should be published.
But Pan says his partners' assertion that the Palomar interferometer is too primitive for reliable research is specious on its face. Pan has published papers describing other binary star systems he has observed with the Palomar instrument -- without raising anyone's hackles.
"You see this? This is a binary star," Pan says, holding a paper with graphs, waves, and plots on it. "I see other binary star, and no one minds. It's not controversial.
"I make a planet disappear, and everyone gets angry."
Pan's claims have not drawn unanimous scientific scorn.
Wesley Traub, a physicist at the Smithsonian Astrophysical Observatory, works on an array of interferometer telescopes in Arizona; they are designed to look at infrared light emitted from stars. Traub worked with Pan at the Harvard Smithsonian Center for Astrophysics and is familiar with work done on the Palomar interferometer. While he can't specifically vouch for Pan's claim to have found binary companions to the famed planet stars, he's taking the results seriously enough to do his own observations on those stars.
"Pan has measured quite a number of binary stars very accurately and beautifully, and I have the highest regard for his experimental technique," says Traub. "You can be absolutely sure we will look at it, and other people will.
"Because if true, it's a really amazing discovery."
Interplanetary Heroine
When you first meet Sallie Baliunas, she strikes you as the kind of woman who, if only she were a few years older, might have been a close friend of Bill Clinton's mother. With her matching lime-green sandals and pantsuit, tousled red hair, and easy, gregarious manner, you can imagine meeting Baliunas at a county fair, or a hot-rod auto show. In one way, you wouldn't be far off the mark: She's the owner of a tricked-out '34 Ford three-window coupe, a '70 Corvette, and a '57 Chevy Bel Aire.
In all the other ways, however, you would have missed the target by light-years. Make no mistake about it, unlikely as it may seem, Baliunas is a hero to the cause of science.
She's wanted to be an astronomer since she was 6 years old, when an Air Force recruiter told her little girls couldn't grow up to be astronauts. Her relentlessness has helped her become one of the world's most accomplished astronomers, a much-sought-after expert on sun spots and the magnetic fields of stars. She spends her time jetting between the Mount Wilson Observatory near Pasadena, where she is deputy director of the Mount Wilson Institute, and Cambridge, Mass., where she is senior astrophysicist at the Harvard Smithsonian Center for Astrophysics. She has been a co-researcher at different times with Marcy, Butler, Gray, and countless other prominent researchers.
These seemingly disparate elements of her character -- the approachable everywoman and the jet-setting astrophysicist -- have made her an ideal diplomat in the zone of doubt surrounding extrasolar planets.
