Astronomers see misaligned planets in distant system

Oct 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: Found: Planets skimming a star's surface

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

Oct 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)

Jun 06, 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

Aug 08, 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 ...

Recommended for you

Evidence for supernovas near Earth

2 hours ago

Once every 50 years, more or less, a massive star explodes somewhere in the Milky Way. The resulting blast is terrifyingly powerful, pumping out more energy in a split second than the sun emits in a million ...

What lit up the universe?

9 hours ago

New research from UCL shows we will soon uncover the origin of the ultraviolet light that bathes the cosmos, helping scientists understand how galaxies were built.

Eta Carinae: Our Neighboring Superstars

17 hours ago

(Phys.org) —The Eta Carinae star system does not lack for superlatives. Not only does it contain one of the biggest and brightest stars in our galaxy, weighing at least 90 times the mass of the Sun, it ...

Best view yet of merging galaxies in distant universe

21 hours ago

Using the Atacama Large Millimeter/submillimeter Array, and other telescopes, an international team of astronomers has obtained the best view yet of a collision that took place between two galaxies when the ...

Image: Hubble stirs up galactic soup

Aug 25, 2014

(Phys.org) —This new NASA/ESA Hubble Space Telescope image shows a whole host of colorful and differently shaped galaxies; some bright and nearby, some fuzzy, and some so far from us they appear as small ...

User comments : 0