New planets likely infernos pelted with iron rain

Updated: Thu Dec. 22 2011 8:33:11 PM

The Canadian Press

MONTREAL ? Their surface likely has temperatures of 8,000 C and chunks of iron probably rain from the sky.

Welcome to KOI 55.01 and KOI 55.02, two new planets discovered by researchers from Universite de Montreal and France’s University of Toulouse.

Although their inhospitable climes wouldn’t be of much interest to future space tourists, the planets do shed new light on what will happen to the Earth when the sun finally winks out, says Universite de Montreal astrophysicist Gilles Fontaine.

“We have demonstrated that planets actually can survive a very violent phase in the evolution of a star,” he said in an interview Thursday.

Up to now, conventional wisdom has been that the Earth and surrounding planets wouldn’t survive the sun’s so-called red giant phase.

That will happen when the sun burns up the remaining halogen that powers it, in about five billion years. The sun will turn red from yellow because it will cool — dropping from about 6,000 degrees Celcius to 3,000 and it will expand to 100 times its current size.

Earth, Mercury and Jupiter would be engulfed and vaporized, the theory went.

“Well, we found something else,” Fontaine said, pointing out that the former red giant the team found — the host star — shed its external layers and had planets around it.

“To us that means quite clearly that planets can, and they do, survive this red giant phase. That’s very important in terms of planet evolution and formation.”

The result of the research was published this week in the prestigious science magazine “Nature.”

Fontaine, one of the world’s foremost experts on the study of white dwarf stars, says researchers didn’t start out looking for planets.

They were using NASA’s Kepler satellite to track the properties of pulsating stars in the Lyra and Cygnus constellations, which lie about 3,900 light years from Earth.

The satellite was looking at an area comprising roughly .3 per cent of the sky. The scientists, who form a team spanning eight countries, were actually looking to target 100,000 stars for observation over several years.

They were going to study the internal structure of stars much the way geoseismologists examine the earth through such things as waves produced by earthquakes.

“We did not look for planets and then — Wow! — there’s these things,” Fontaine said.

And he adds there is likely a third planet floating around there but it wasn’t included in the current results because the data is still too slim.

The scientists didn’t actually see the new planets but decoded information in light and thermal modulations sent back by the satellite.

The discovery is also significant because even though scientists have discovered 1,500 planets over the years, not many have had their characteristics documented.

Fontaine said researchers were able to calculate that the new planet’s host star — their equivalent to Earth’s sun — probably burned at around 28,000 degrees, leading him to believe the planets themselves “must be a real inferno.”

And, no, there probably isn’t any life on them.

“Certainly in that environment, life, if it did exist before, certainly doesn’t exist anymore,” Fontaine said.

“We’re basically talking mainly about the rocky and metallic remains of probably former Jupiter-like planets that have lost their volatile elements in the past so we are left with a rocky core.”

He said they are probably made of heavy metals like iron and there could be a rain of iron droplets from their atmosphere.

“Not a good place to be,” the astroseismologist said.

Fontaine was hard-pressed to contain his glee at the discovery, saying, “We’re pretty happy with these unexpected results.”

“We were basically amateurs in terms of planets when we started but we learned a lot.”

But don’t expect Fontaine to name one of the planets after himself at some point. A commission of the International Astronomical Union handles that and the current monikers are basically catalogue numbers.

“You’re not allowed to name an object in the sky at will,” Fontaine said. “You have to follow the rules.”

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