Archive for August 27th, 2009

When Worlds Collide

Okay, so they can’t even get along out there in space.

In the constellation Phoenix, a star and a planet are hissing and spitting at one another. The planet Wasp-18b, ten times the size of Jupiter, races around its sun, Wasp-18, in less than a day. The two worlds are so close—less than 1.9 million miles—that the fiery planet causes tremendous plasma tides on the sun.party Those tides in turn are warping the orbit of the planet, and will, within 650,000 years or so, cause Wasp-18b to sidle in past “the Roche limit,” at which time it will begin to break apart, and finally plunge into its own sun.

At least that’s the theory of Coel Hellier, a professor of astrophysics at the UK’s Keele University, who, with a motley crew of co-authors, soberly reported in Nature what USA Today has elected to describe as “an ever-closer tango of death.”

Its size—10 times bigger than Jupiter—and its proximity to its star make it likely to die, Hellier said.

Think of how the distant moon pulls Earth’s oceans to form twice-daily tides. The effect the odd planet has on its star is thousands of times stronger, Hellier said.

Or maybe the theory is bollocks. After all, earth observers don’t know very much about far-off planets yet. In fact, when I was a lad—not that long ago—terran astronomers had not perceived any planets outside our own solar system, and many thought they didn’t exist anywhere else at all. Wrong. To date, 373 planets have been detected outside our own system; Wasp-18b is “yet another weird one in the exoplanet menagerie,” says planet specialist Alan Boss of the Carnegie Institution.

Some people are calling Wasp-18b a “suicide planet”; one heavy-breathing astro-blogger has even dubbed it “the red hot planet of doom.” Others are less exercised. University of Maryland astronomer Douglas Hamilton, for instance, questions whether Wasp-18b is actually bent on suicide. He suggests instead “that some basic physics calculations that all astronomers rely on could be dead wrong.”

Folks should know soon. As explained here, if Wasp-18b is indeed offing itself, in a decade its orbital period should be 28 seconds shorter. If it isn’t, “then theorists will have to retool their ideas about the inner workings of stars.” Stay tuned.


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