Two Exoplanets Found in Extremely Close Proximity

http://zen-haven.dk/two-exoplanets-found-in-extremely-close-proximity/

They’re space’s odd couple, a rarity never seen before – an Earth-like planet locked in a tug-of-war with it’s much larger, Neptune-sized, neighbour.

Astronomers, using data provided from Nasa, say Kepler-36b (a rocky planet like our own but 4.5 times the size) and Kepler-36c (most likely a gas giant) occupy nearly the same orbital plane and come within about 1.9 million kilometres of each other – about 20 times closer to one another than any two planets in our solar system.

However, the timing of their orbits mean they’ll never collide, said Eric Agol, a University of Washington astronomy professor.

“These are the closest two planets to one another that have ever been found,” Agol said. “The bigger planet is pushing the smaller planet around more, so the smaller planet is harder to find.”

The larger planet was originally spotted in data from Nasa’s Kepler satellite, which uses an instrument to measure light from distant celestial objects and can detect a planet when it transits, or passes in front of, and briefly reduces the light coming from, its parent star.

The planets’ proximity allowed the scientists to make fairly precise estimates of each planet’s characteristics, based on their gravitational effects on each other and the resulting variations in the orbits.

They believe the smaller planet is 30 per cent iron, less than 1 per cent atmospheric hydrogen and helium and probably no more than 15 per cent water.

The larger planet, on the other hand, likely had a rocky core surrounded by a substantial amount of atmospheric hydrogen and helium.