Here's an astronomy love story to warm your heart: 370 light-years away from Earth, a star's heart has been set aflutter by the proximity of its planet.
The star, which has been given the ungainly title HAT-P-2, is orbited by a “hot Jupiter.” This does not refer to an extremely sexy planet, though gas giants are indeed notoriously good looking. Instead, it describes a class of planets that are extremely large — the one in our story is eight times our own Jupiter's size — and orbit incredibly close to their suns.
HAT-P-2b, as the planet is named, has a highly eccentric orbit that more resembles a squashed oval than a circle. This sometimes brings it very close to its sun, while other times it swings far, far away (kind of like your awful ex-boyfriend).
Astronomers at the Spitzer Space Telescope in California spent more than 350 hours observing this celestial couple from afar. They found that the star's brightness oscillated according to the exact rhythm of its planet's orbit.
According to their new study, published Tuesday in the Astrophysical Journal Letters, each time the planet reaches its closest approach, it appears to “give the star a little kiss,” as NASA puts it. In other words, the gravitational forces of the two bodies interact about once every 5.6 days, and in response, the star begins to vibrate as though it's been struck by a bell.
“They were very tiny signals,” MIT astronomer Julien de Wit, lead author of the study, said in a statement. “It was like picking up the buzzing of a mosquito passing by a jet engine, both miles away.”
The researchers say that phenomenon can't be caused by problems with their instrument or boiling material in the star itself. The sun must be pulsing in response to its planet.
Researchers can't yet explain the physical link between the two celestial bodies. It's the first time they've ever spotted a planet affecting its star in this way. HAT-P-2b, the planet, is just 1/100th the size of its sun — pretty small to have such a strong effect.
The finding suggests that, when it comes to star-planet relationships, scientists have a lot more to learn.
“This is really exciting because, if our interpretations are correct, it tells us that planets can have a significant impact on physical phenomena operating in their host-stars,” co-author Victoria Antoci, a researcher at Aarhus University in Denmark, said in the statement. “In other words, the star ‘knows’ about its planet and reacts to its presence.”