NASA's Kepler Spacecraft Spots Tilted Orbits That Surprise Astronomers
The solar system of a red giant star four times larger than the sun and located approximately 3,000 light years from Earth has given astronomers new information about previously unknown angled orbits.
Data on the giant star, with the unassuming name of Kepler-56, and its planets came via NASA's Kepler space telescope. A team of international scientists analyzed the fluctuations in brightness at different points on the surface of Kepler-56 and discovered that the star's rotation axis is tilted by about 45 degrees to our line of sight, according to information released on NASA's website.
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"This was a surprise because we already knew about the existence of two planets transiting in front of Kepler-56," said the study's lead researcher Daniel Huber, who is based at NASA's Ames Research Center in Moffett Field, Calif. "What we found is quite literally a giant misalignment in an exoplanet sytem."
The results of the study, "Stellar Spin-Orbit Misalignment in a Multiplanet Sytem," are published in the Oct. 18 issue of the journal Science.
The Kepler-56 systems has three planets, with two of them closer to the star and a much larger one further out.
"This is a new level of detail about the architecture of a planetary system outside our solar system," said Steve Kawaler, professor of physics and astronomy at Iowa State University, one of the co-authors of the study and a leader of the Kepler asteroseismic investigation. Asteroseismology is the study of the internal structure of stars.
"These studies allow us to draw a detailed picture of a distant system that provides a new and critical test of our understanding of how these very alien solar systems are structured," said Kawaler, who was part of a team that measured the oscillation in frequencies and used spectroscopy data about the star's temperature and chemistry to measure the star's diameter and properties, according to an Iowa State University press release.
The inner planets are orbiting at a tilt to the equator of the host star. Astronomers have previously found tilted orbits in planetary systems that feature a "hot Jupiter" — a giant gas planet that closely orbit their host star, according to NASA's website.
But until now, the tilted orbits haven't been observed in multiplanetary systems without such a big interloping planet.
Generally, migrating hot Jupiters change their orbits after encounters with other planets and material, and therefore have a higher chance of tilted orbits. In the case of Kepler-56, however, the more massive outer planet seems to be maintaining the tilted orbits of the two inner planets, according to Kawaler. "It issues a continuous tug on the orbit of the smaller ones, pulling them into their inclined orbits," he said.
"We know now that misalignments are not just confined to hot Jupiter systems," said Huber. "Further observations will reveal whether the tilting mechanism in Kepler-56 could also be responsible for misalignments observed in hot Jupiter systems."
"This is a very puzzling result that is sure to challenge our understanding of how solar systems form, "said co-author of the report Tim Bedding, a researcher at the University of Sydney, told Universe Today.
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