8/11/2019 Clemson Astrophysicist Discovers New Evidence of a Forming Planet

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Clemson astrophysicist discovers new

evidence of a forming planet

Ron Barnett, rbarnett@greenvillenews.com 10:10 a.m. EDT September 4, 2014

(Photo: PATRICK COLLARD , Staff )

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Being a serious scientist, Sean Brittain is not leaning toward naming the gaseous giant orb histeam discovered 325 light years away "Planet Clemson."

But considering that the telltale sign of its existence is a 60-million-mile oblong disk shaped like

the eye of a Tiger, you couldn't blame him if he did.

The planet, which is at least three times the size of Jupiter, is orbiting a blue star that's 21/2 times

as big and 30 times as bright as the sun, according to Brittain, an associate professor ofastrophysics at Clemson University.

What's special about this discovery for scientists, though, is that it's the first time a planet beendetected while still in its formative stages using "spectro-astrometry," a technique that makes it

possible to measure the movement of the emissions that are forming the gaseous world.

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Brittain and an international team of scientists he led have been collecting data for over a decade,

studying changes in the Doppler shift of the glowing gas disk surrounding the planet.

Just as the pitch of a passing car is higher as it approaches and lower as it moves away, the

appearance of light waves change from blue to red when an object is moving closer or father

away fast enough. Brittain does his work in the infrared part of the spectrum, but the specialtelescopes he uses are able to detect Doppler shift in the spectra of some of the gasses

surrounding the new planet that indicate the direction of movement.

When the first observations were made by one of the team members in 2003, the spectral lines of

the gas were symmetric. Brittain took measurements in 2006 that showed an extra source of

emission that was red-shifted.

"At the time we didn't really know what was causing that change," he said.

More measurements were made in 2010 and that showed a shift toward the blue range of the

spectrum.

"That was pretty exciting but it wasn't conclusive," he said.

Since the star, called HD100546, can be viewed only from the Southern hemisphere, it took

numerous trips to Chile to do the detective work needed to confirm what the team believed: That

a planet was sucking in the gas closest to the star and forming the cat-eyed shape in the sky.

On his most recent visit to the observatory in 2013, Brittain found the evidence he was lookingfora bluish tint to the gas indicating that the planet was moving in orbit around the star and

traveling in the direction of Earth during that part of its circuit.

"It's almost like water swirling around a toilet," he said, noting that the gas speeds up relative tothe vantage point on earth from zero to six kilometers per second as it moves in an orbit that will

take 30 years to complete.

The findings of the team, which included John S. Carr of the Naval Research Laboratory in

Washington, D.C.; Joan R. Najita of the National Optical Astronomy Observatory in Tucson,

AZ.; and Sascha P. Quanz and Michael R. Meyer, both of ETH Zurich, Institute for Astronomy,have just been published in The Astrophysical Journal.

"Astronomers are now very good at finding already formed planets around many nearby stars,

but it has been difficult to watch the planets in the process of forming," said Mark Leising, thechair of Clemson's Astronomy and Astrophysics Department.

"Using very clever techniques and the most advanced telescopes on Earth, they have

accomplished that. It's great to see our faculty working with leading institutions around the world

to make discoveries at the forefront of astronomy."

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Carr said the findings confirm what scientists have predicted about the way planets are formed

from pizza-shaped disks of matter that circle stars.

"The possibility that we have caught a planet in the act of formation is an exciting result," he

said. "What makes this work doubly interesting is the evidence that we are seeing gas as it swirls

around and flows onto the planet to feed its continuing growth."

Najita said the collaborators "stumbled onto this project" by a mutual interest in studying carbon

monoxide emissions, which are much easier to detect than the more common element, hydrogen.

"It was uncanny that the first system we studied actually showed the signature of orbital motion,"she said. "It's not every day that you look for something exciting and actually find it."

Members of Brittain's team previously discovered evidence of what could become a planet

eventually around this same star, which is in the constellation Musca, or The Fly.

"It is in the process of collapsing," Brittain said. "Maybe in a million years you'll have anotherplanet and disk."

By studying both, the team will be able to better understand the stages of the development ofplanets, Quanz said.

"If our interpretation is correct, these two planets have different evolutionary stages with theinner one being older than the outer one," Quanz said. "This means that for the first time we can

now study directly different phases of gas giant planet formation and this around a singlestar."

Even if it weren't an inhabitable gas giant like Jupiter and Saturn, the newly discovered plantwon't make it as a candidate for a future satellite campus of Clemson University, or a home forhumankind after our sun burns out.

According to Brittain, this type of star, although younger than our own, will die long before thesun turns into a red giant and vaporizes the Earth.