The newest exoplanet a world of ridiculous extremes: it orbits its star at a mere fraction of the distance between the Sun and Mercury, it's four times the size of Jupiter, and the planet's temperature is hotter than some stars.


Astronomers have discovered a bunch of exoplanets that push our conception of what a planet can be to its absolute limit, but WASP-33b is just ridiculous. The planet orbits its star at a distance that's only seven percent of Mercury's. That means its "year" only lasts a piffling twenty-nine hours, but its temperature is what's really ludicrous. It has a surface temperature of nearly 6,000 degrees Fahrenheit, which is hotter than the surface of some red dwarf stars. By comparison, the hottest planet in our solar system is Venus, which only clocks in at a positively chilly 860 degrees.

Its extreme proximity to its star is part of the reason why WASP-33b is so unimaginably hot. But the star itself is much hotter than most stars, with an estimated temperature of 13,000 degrees. It's quite a bit hotter than our Sun, which is "only" 10,000 degrees. With WASP-33b so close to this enormous blast furnace, it's hardly surprising that it's so incredibly hot.


This star system offers an exciting opportunity to study "Hot Jupiters", which are Jupiter-sized planets located extremely close to their Sun. Their properties have often baffled astronomers, as they actually appear to have a hotter inner atmosphere than outer one. That's unexpected, as these planets' stars should be heating up the outer atmosphere far more than any internal processes ever could.

It's possible than exotic carbon-based chemicals might somehow alter the way a planet's atmosphere processes radiation. These chemicals would have to be formed by the outpouring of ultraviolet radiation from the star. WASP-33b should be getting exceptionally high doses of ultraviolet radiation from its star, which increases the chances astronomers will be able to figure out what happens with hot stars and hot planets.

[arXiv via New Scientist]