The discovery, made using NASA's Infrared Telescope (IRTF), will be detailed in the July 4 issue of the journal Nature. Early pieces of the data were was first presented in a relatively obscure poster session during a meeting of the American Astronomical Society in January.

The temperature of the substance indicates it is concentrated roughly 7 to 10 astronomical units (AU) from the star, according to Terrence Rettig, a University of Notre Dame researcher who conducted the study with colleague Sean Brittain. One AU is the distance from Earth to the Sun. Saturn orbits at 9.2 AU.

Rettig said follow-up observations are planned to pin down whether the chemical is indeed associated with a planet.

"The answer is not clear yet but the detection is intriguing," Rettig told SPACE.com. "More observations will clarify where it is in the disk as well as how it is formed, which will tell us if H3+ is concentrated in a protoplanet or in the disk."

Researchers have known for a few years that the star, called HD 141569, has a disk of gas and dust surrounding it. Such disks are leftovers of star formation, theory holds, and provide the seeds of planetary birth. Our own solar system is thought to have evolved from one of these so-called protoplanetary disks.

In recent years, astronomers have found and begun to explore several of these disks. In one recent case, astronomers found evidence for a developing planet as a star winked, indicating the possible passage of a large blob of material that had not yet fully condensed into the smaller sphere it might one day become.

Though few astronomers would argue the point, it is not yet proven whether planets actually form in the disks.

Separate observations in 1999 by the Hubble Space Telescope examined the outer portion of the disk around HD 141569. Hundreds of AU from the star, Hubble found hints that other planets might be developing.

HD 141569 is 320 light-years away. Because the star is only about 4 million years old (our Sun is about 5 billion years old) it may represent a snapshot of solar system formation that would help astronomers learn more about what happened here.

And astronomers are far from sure exactly what happened here. While there is wide agreement on how rocky planets like Earth probably formed, theorists are still grappling with how to build gas giants like Jupiter.

"The finding may provide a vital clue to how hydrogen and helium condense into gas-giant planets," says University of Chicago researcher Takeshi Oka, who wrote an analysis of the discovery for Nature. "If the findings are confirmed, Brittain and Rettig have discovered a new astronomical object, opening up a new avenue for the study of the formation of giant planets."

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