'Roaster' Planet Warms Up Its Sun (Hot Jupiter effect)

Yahoo News ^ | 1/8/04 | Deborah Zabarenko- Reuters

[NormsRevenge]

ATLANTA (Reuters) -

Stars heat planets: that's the astronomical rule. But a big gassy planet in the constellation Sagittarius is warming the star it orbits, just the opposite of what happens between Earth and the sun, scientists said on Wednesday.

The hot spot on the star, known to astronomers as HD179949, might have been mistaken for a sun spot except that it is moving at the pace of the planet's orbit, rather than at the speed the star is rotating.

"This is the first glimpse of a magnetic field on an extrasolar planet," Canadian researcher Evgenya Shkolnik of the University of British Columbia said at a meeting of the American Astronomical Society in Atlanta.

This magnetic field is what seems to be causing the spot warming on the star, which is some 90 light-years away, a stone's throw in cosmic terms. A light-year is about 6 trillion miles, the distance that light travels in a year.

The "roaster" planet being studied is almost as big as Jupiter, a gas giant planet in our solar system, and has 270 times the mass of Earth.

Unlike Earth or Jupiter, though, the planet is nestled very close to its star, only 4.35 million miles or so, compared to the 93 million miles between Earth and the sun.

Such close-in planets are called "roasters" or "hot Jupiters" because of their proximity to their stars; these hot planets account for about 20 percent of the more than 100 planets outside our solar system identified so far.

This one is apparently causing a giant magnetic storm on its star, producing a persistent hot spot that keeps pace with the planet in its three-day orbit around the star. The hot spot has been seen for more than a year, or more than 100 orbits, Shkolnik said.

The star itself rotates every nine days, but the hot spot seems to correspond to the planet and not the star's rotation.

The traveling hot spot is probably caused by an interaction between the planet's magnetic field and the star's chromosphere, a thin, hot layer above its visible surface.

Shkolnik and her colleagues detected the strange relationship using the Canada-France-Hawaii Telescope at Mauna Kea, Hawaii.

More information and a picture are available online at cadc.hia.nrc.ca/cfht/aas.

[NormsRevenge]

An artists impression released January 7, 2004 shows a closely-orbiting giant planet inducing flare-like activity on its parent star through a magnetic interaction between both bodies. Stars heat planets: that's the astronomical rule. But a big gassy planet in the constellation Sagittarius (as depicted in this illustration) is warming the star it orbits, scientists said January 7, 2004. The hot spot on the star, known to astronomers as HD179949, might have been mistaken for a sun spot except that it is moving at the pace of the planet's orbit, rather than at the speed the star is rotating. (EDITORIAL USE ONLY, NO SALES) REUTERS/HO/University of British Columbia/illustration by Shane Erno

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[farmfriend]

ping

[LiteKeeper]

read later

[Focault's Pendulum]

Maybe it's a brown dwarf.

[punster]

What about the influence of gravitational tides? That also seems a consideration in this case.

[petuniasevan]

It's too small; it would need to have at least 15 times Jupiter's mass. The planet orbiting HD179949 is 270 times the mass of Earth; Jupiter is 318 times Earth mass.

[SunkenCiv]

from 2004.

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