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Tilted Suns – Weird Exoplanet Systems
The Earth’s axis of rotation is tilted 23.4 degrees to its orbital motion around the Sun (more precisely, its spin axis has a tilt of 23.4 degrees with respect to the axis of its orbit). This tilt, which causes our seasonal variations, was likely the result of a cataclysmic impact that occurred about 4.5 billion years ago between the Earth and another large body which probably also resulted in the formation of the moon.
The tilt of a star’s spin is obviously an important feature, but knowing it first requires knowing the orbit of its planets. One amazing and serendipitous result of the Kepler mission and its powerful ability to find transiting planets is its ability – by characterizing planetary systems – to address the issue of stellar tilts.
Stellar tilts measured so far in exoplanetary systems display a surprising diversity, from very small values like our Sun’s to strongly tilted stars, and even some “retrograde” stars whose direction of rotation is opposite to the planetary orbital revolution.
An artist’s conception of Kepler-56, an evolved star with two planets and a large tilt. Credit: Daniel Huber / NASA Ames
PHYS.ORG
Read more here: http://phys.org/news/2013-11-tilted-suns.html
Journal reference: Science
Provided by Harvard-Smithsonian Center for Astrophysics
