Exoplanet WASP-18b

From http://www.skyandtelescope.com/news/55066637.html

WASP-18b orbits incredibly close to its host star, circling just 1.4 million miles (2.2 million km) from its surface. From such a ringside seat, the planet's star-facing hemisphere broils at an estimated 3,800°F (2,400K).

What has Hellier's team scratching its collective head is not that WASP-18b is so hot (it's too dense to simply evaporate), but instead why it exists at all!

Here's the conundrum: With roughly 10 times the mass of Jupiter, it's hefty enough and close enough to raise a significant tidal bulge on the star. And because it orbits in just 22½ hours, faster than any other confirmed hot Jupiter and much faster than the star spins, this tidal interaction is likely dragging the planet inward to its doom — and fast.

The Earth-Moon system is a good example of such a tidal yin-yang. The Moon likewise raises tides in Earth's oceans, and their mutual attraction transferring angular momentum between them. However, because the Moon orbits much more slowly than Earth turns, the tradeoff is gradually pushing the Moon away from us (1½ inches, or 38 mm, per year) and our day is ever-so-slightly getting longer (0.2 second per century). But in the WASP-18 tidal dance, it's the other way around — the planet is spiraling inward, and the star's spin is speeding up.