Astronomers see misaligned planets in distant system

October 17, 2013
The Kepler-56 planetary system features two inner planets orbiting at a severe tilt to their host star -- even though there's no "hot Jupiter" in the system. Credit: Daniel Huber, NASA/Ames Research Center

Using data from NASA's Kepler space telescope, an international team of astronomers has discovered a distant planetary system featuring multiple planets orbiting at a severe tilt to their host star.

Such tilted orbits had been found in featuring a "hot Jupiter," a giant planet in a close to its . But, until now, they hadn't been observed in multiplanetary systems without such a big interloping planet.

The discovery is reported in a paper, "Stellar Spin-Orbit Misalignment in a Multiplanet System," published in the Oct. 18 issue of the journal Science. The lead author of the study is Daniel Huber of NASA's Ames Research Center in Mountain View, Calif. Steve Kawaler, an Iowa State University professor of physics and astronomy and a leader of the Kepler Asteroseismic Investigation, is a co-author.

"This is a new level of detail about the architecture of a planetary system outside our solar system," Kawaler said. "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."

Kawaler contributed as part of the research team that studied regular changes in the brightness of the host star, Kepler-56, an aging red giant star with two planets in close orbits and a massive third planet in a distant orbit. By measuring those oscillation frequencies and using spectroscopy data about the star's temperature and chemistry, researchers measured the star's diameter and other properties.

The paper reports Kepler-56 is more than four times the radius of our sun. Its mass is also 30 percent greater than our sun. It is about 3,000 light years from Earth.

Kawaler said he was also part of the team that used studies of the changes in brightness to help determine the tilt of the rotation axis of Kepler-56. That axis is tilted 45 degrees to the line of sight from Earth.

Generally, Kawaler said, the simplest way for a planetary system to develop is with the orbits in the same plane as the host star's equator. That typically indicates the planets formed from a thin disk of dust and gas surrounding the host star. The planets in our all orbit within 7 degrees of the plane of the sun's equator.

A planet orbit that tilts away from other planets or from the host star's equator can mean the planet had a traumatic youth, Kawaler said. It may have been pulled into a different plane after encountering another planet or planets. That's generally the case with migrating hot Jupiters. They 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 .

"It issues a continuous tug on the orbit of the smaller ones, pulling them into their inclined orbits," Kawaler said.

All of those Kepler-56 observations, the researchers noted in their Science paper, add up to firm evidence that tilted planetary orbits are possible even in systems that don't contain a hot Jupiter.

Explore further: Tiny exoplanet smaller than Mercury: Smallest planet yet found outside solar system (Update)

More information: "Stellar Spin-Orbit Misalignment in a Multiplanet System," Science, 2013. www.sciencemag.org/content/342/6156/331.abstract

Related Stories

Found: Planets skimming a star's surface

October 11, 2013

A new planet-hunting survey has revealed planetary candidates with orbital periods as short as four hours and so close to their host stars that they are nearly skimming the stellar surface. If confirmed, these candidates ...

Stars don't obliterate their planets (very often)

June 6, 2013

(Phys.org) —Stars have an alluring pull on planets, especially those in a class called hot Jupiters, which are gas giants that form farther from their stars before migrating inward and heating up.

Two more kepler planets confirmed

August 8, 2011

Hot on the heels of confirming one Kepler planet, the Hobby-Eberly Telescope announces the confirmation of another planet. Another observatory, the Nordic Optical Telescope, confirms its first Kepler planet as well, this ...

Recommended for you

Freeze-dried food and 1 bathroom: 6 simulate Mars in dome

January 20, 2017

Crammed into a dome with one bathroom, six scientists will spend eight months munching on mostly freeze-dried foods—with a rare treat of Spam—and have only their small sleeping quarters to retreat to for solace.

Image: Wavemaker moon Daphnis

January 20, 2017

The wavemaker moon, Daphnis, is featured in this view, taken as NASA's Cassini spacecraft made one of its ring-grazing passes over the outer edges of Saturn's rings on Jan. 16, 2017. This is the closest view of the small ...

Video: A colorful 'landing' on Pluto

January 20, 2017

What would it be like to actually land on Pluto? This movie was made from more than 100 images taken by NASA's New Horizons spacecraft over six weeks of approach and close flyby in the summer of 2015. The video offers a trip ...

The evolution of massive galaxy clusters

January 20, 2017

Galaxy clusters have long been recognized as important laboratories for the study of galaxy formation and evolution. The advent of the new generation of millimeter and submillimeter wave survey telescopes, like the South ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.