Kepler-30 Distant Solar System Shows Similar Geometry To Our Own
Lee Rannals for redOrbit.com – Your Universe Online
Astronomers have used NASA’s Kepler to help spot another planetary system that has its planets neatly aligned, similar to our own Solar System.
The study shows the trio of planets orbiting the star within one degree, relative to each other, and relative to the star’s equator, showing a sense of geometry in its alignment.
“In our solar system, the trajectory of the planets is parallel to the rotation of the sun, which shows they probably formed from a spinning disc,” Roberto Sanchis-Ojeda, a physics graduate student at MIT who led the research, said. “In this system, we show that the same thing happens.”
The finding dictates that Kepler-30 is similar to our own Solar System in that it formed from a rotating disk of gas.
The NASA telescope is studying roughly 150,000 sun-like stars in an attempt to find earth-like planets hundreds to thousands of light years away.
Kepler-30 lies 10,000 light years away from Earth and has a star similar in size to our sun that rotates around a vertical axis.
The team’s findings may help explain the origins of certain systems, while also helping to shed a little more light on our own solar system.
“It’s telling me that the solar system isn’t some fluke,” said Josh Winn, an associate professor of physics at MIT and a co-author on the paper published in the journal Nature. “The fact that the sun’s rotation is lined up with the planets’ orbits, that’s probably not some freak coincidence.”
He said the discovery may back up a theory of how hot Jupiters form. These gas giants are found extremely close to their white-hot star host, and complete an orbit in a matter of hours or days.
Scientists thought that these misalignments might be a clue to their origins, because the orbits may have been knocked askew in the very early period of a planetary system’s formation.
Scientists have recently identified a number of hot Jupiter systems, but to prove the theory, the researchers have to identify a non-hot Jupiter system. Finding a system aligned similar to our solar system would provide evidence that only hot Jupiter systems are misaligned.
The team looked through Kepler data and narrowed in on Kepler-30, which had much longer orbits than a typical hot Jupiter. To measure the alignment of the stars, they tracked its sunspots.
“These little black blotches march across the star as it rotates,” Winn said. “If we could make an image, that’d be great, because you’d see exactly how the star is oriented just by tracking these spots.”
Stars like Kepler-30 are extremely far away, so capturing an image of them is nearly impossible, and the only way to document these stars is to measure the small amount of light they give off. So, the team tracked sunspots using the light of these stars.
Every time a planet transited the star, it blocked off a bit of starlight, so astronomers saw a dip in light. If a planet crossed a dark sunspot, the amount of light blocked decreases.
“If you get a blip of a sunspot, then the next time the planet comes around, the same spot might have moved over here, and you’d see the blip not here but there,” Winn said. “So the timing of these blips is what we use to determine the alignment of the star.”
The team concluded that Kepler-30 rotates along an axis perpendicular to the orbital plane of its larger planet. This helped them determine the alignment of the planets’ orbits.
By measuring the timing variations of planets as they transit the star, they determined the orbital configurations and found that all the planets are aligned along the same plane.
“In order to understand how common life is in the universe, ultimately we will need to understand how common stable planetary systems are,” said James Lloyd, an assistant professor of astronomy at Cornell University who was not a part of the research. “We may find clues in extrasolar planetary systems to help understand the puzzles of the solar system, and vice versa.”