Evidence of forming planet discovered 335 light years from Earth

This graphic is an artist’s conception of the young massive star HD100546 and its surrounding disk. 

Credit: P. Marenfeld & NOAO/AURA/NSF

An international team of scientists led by a Clemson University astrophysicist has discovered new evidence that planets are forming around a star about 335 light years from Earth.

The team found carbon monoxide emission that strongly suggests a planet is orbiting a relatively young star known as HD100546. The candidate planet is the second that astronomers have discovered orbiting the star.

Theories of how planets form are well-developed. But if the new study's findings are confirmed, the activity around HD100546 would mark one of the first times astronomers have been able to directly observe planet formation happening.

New discoveries from the star could allow astronomers to test their theories and learn more about the formation of solar systems, including our own, said Sean Brittain, an associate professor of astronomy and astrophysics at Clemson.

"This system is very close to Earth relative to other disk systems," he said. "We're able to study it at a level of detail that you can't do with more distant stars. This is the first system where we've been able to do this.

"Once we really understand what's going on, the tools that we are developing can then be applied to a larger number of systems that are more distant and harder to see."

For more than a decade, the team has focused some of Earth's most powerful telescopes on a disk-shaped cloud of gas and dust that surrounds HD100546.

The star is about 2.5 times larger and 30 times brighter than the sun, Brittain said. It's in the constellation Musca, or The Fly, and can only be seen from the Southern Hemisphere.

Brittain made three trips to Chile as far back as 2003 to gather data for the research. He used telescopes at the Gemini Observatory and the European Southern Observatory.

The new planet astronomers believe they have found what would be an uninhabitable gas giant at least three times the size of Jupiter, Brittain said. Its distance from the star would be about the same distance that Saturn is from the sun.

The team used a technique called "spectro-astrometry," which enables small changes in the position of the carbon monoxide emission to be measured.

A source of excess carbon monoxide emission was detected that appears to vary in position and velocity. The varying position and velocity are consistent with orbital motion around the star.

More information: Astrophysical Journal paper - dx.doi.org/10.1088/0004-637X/791/2/136, Preprint on Arxiv: arxiv.org/abs/1409.0804

Astrophysical Journal Letters paper - iopscience.iop.org/2041-8205/766/1/L1/ , Preprint on Arxiv: arxiv.org/abs/1302.7122