Wild temperature swings on a distant exoplanet called 55 Cancri e could be evidence of gigantic eruptions on a super-Earth.
Of all the recent discoveries reported of late from worlds outside our solar system, a new find may be the most extraordinary yet: A world known as 55 Cancri e, just 40 light-years from Earth, might be volcanically active.
“It’s super exciting,” says Cambridge University astrophysicist Nikku Madhusudhan, co-author of a paper just published online at arXiv.org about the discovery .
When astronomers first began discovering exoplanets back in the 1990s, they figured it would take a bigger, more powerful successor to the Hubble to study them in any detail. They were wrong. Even with the launch of the James Webb Space Telescope still several years in the future, exoplanet experts have managed to probe the atmospheres of these distant worlds; determine whether they’re gaseous, like Jupiter, or rocky, like Earth; and find what appears to be gigantic storms whipping across them.
It’s not the volcanoes themselves that have astronomers excited; it’s getting a better look at what exoplanets are actually like. The ultimate goal is to find a planet that supports life, and the more scientists can say about conditions on individual worlds, the better they can target their searches. This is one more step along that road—and, says Madhusudhan, “in our wildest imaginations, we couldn’t have guessed we’d be making discoveries like this as early as 2015.”
The discovery isn’t iron-clad yet, however, cautions Madhusudhan. “We don’t want to jump to conclusions,” he says. What he and his colleagues actually see with the Spitzer Space Telescope is a dramatic variation in the planet’s temperature—from about 1880°F at the “cooler” end to nearly 5,000°F at the hotter. “It’s the first time we’ve seen such a huge level of variability,” said Brice-Olivier Demory, also of Cambridge and the paper’s lead author.
Even at the cool end, 55 Cancri e, which is about twice as big as Earth and nearly eight times as massive, is far too hot to support life. If the surface is made of rock, as astronomers believe, it’s either partly or entirely molten. But the wide swings—from the lower temperature in 2012 to the higher in 2013—make it clear that something is going on. It could be variations in the star itself, say the scientists, but those would tend to be random. It could be an illusion of sorts: maybe the planet is being eclipsed every so often by a cloud of gas or dust orbiting the parent star. That could make the 55 Cancri e dimmer, which would make it seem cooler to observers.
Volcanism, however, could also dim the planet, and the astronomers consider that to be more likely. “We know it happens all over our own solar system,” says Madhusudhan. “We see evidence for it on Venus, Mars, Io, all kinds of solid bodies. That’s the natural explanation.”
More: http://news.nationalgeographic.com/2015/05/150506-volcano-planet-space-cancri-astronomy/