Warm patch on planet is in the ‘wrong spot’, scientists say

The planetary hot spot is in the wrong place to be caused by the glare of its star. Image: NASA

A warm spot discovered on an exoplanet has confused the NASA astronomers who found it, because it wasn’t in the place they expected it.

Upsilon Andromedae b is a gas giant with one side of the planet always facing its sun. It has been described as a “˜hot Jupiter’, a type of planet with “˜gaseous constitutions’ and high temperatures.

Previous observations suggested that hot spots on exoplanets may be shifted slightly away from the sun’s glare, rather than located directly under it. Scientists have previously thought that these offsets might be caused by winds pushing the hot gases around.

But the hot spot on upsilon Andromedae b is offset by 80 degrees from the sun’s heat, placing it squarely on the other side of the planet. Ian Crossfield, the lead author of a study on the finding, said that they had not expected to find such a large offset. He stated in the press release “It’s clear that we understand even less about the atmospheric energetics of hot Jupiters than we thought we did”.

This anomaly was revealed by the Spitzer Space Telescope at NASA, the first telescope to detect a planet orbiting a star (other than our sun). It has been used to detect the variations in the infra-red light emitted by upsilon Andromedae b and its star, with the hottest part of the planet giving off the most light.

The brightest part of the system was detected when the planet was located to one side of its star, with the hot spot facing Earth. Scientists have suggested star-planet magnetic interactions and supersonic winds as a possible cause of the hot spot.

Michael Werner, the Spitzer project scientist at NASA’s Jet Propulsion Laboratory, has described this as a very unexpected result. In the press release he stated “Spitzer is showing us that we are a long way from understanding these alien worlds”.


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