Astronomy Now Home
Home Magazine Resources Store

On Sale Now!



The September 2014 issue of Astronomy Now is on sale! Order direct from our store (free 1st class post & to UK addresses). The Astronomy Now iPad/iPhone editions are now available worldwide on the App Store.



Top Stories



Earthshine used to test life detection method
...By imagining the Earth as an exoplanet, scientists observing our planet's reflected light on the Moon with ESO's Very Large Telescope have demonstrated a way to detect life on other worlds...
  READ MORE

Solid buckyballs discovered in space
...Astronomers using NASA’s Spitzer Space Telescope have detected a particular type of molecule, given the nickname “buckyball”, in a solid form for the first time...
  READ MORE

Steamy water-world gets the Hubble treatment
...Hubble Space Telescope observations of a 7 Earth-mass planet find an unusual water-rich world swathed in a thick, steamy atmosphere...
  READ MORE








A giant misalignment in a multi-planet system
NASA PRESS RELEASE
Posted: 22 October 2013


A long-standing puzzle in the study of exoplanets is the formation of hot Jupiters, gas giant planets that snuggly orbit their host star. To explain their short orbital periods, theory suggests that hot Jupiters form in long orbits and then quiescently migrate through the protoplanetary disc, the flat ring of dust and debris that circles a newly fashioned star and coalesces to form the planets.


Graphical sketch of the Kepler-56 system. The line of sight from Earth is illustrated by the dashed line, and dotted lines show the orbits of three detected companions in the system. The solid arrow marks the rotation axis of the host star, and the thin solid line marks the host star equator. Image credit: NASA GSFC/Ames/D. Huber
 
This theory was challenged when the orbital plane of hot Jupiters were discovered to be frequently misaligned with the equator of their host stars. Scientists interpreted this as evidence that hot Jupiters are the result of chaotic close encounters with other planets.

A decisive test between the two theories are systems with more than one planet: if misalignments are indeed caused by dynamical perturbations which lead to the creation of hot Jupiters, then multi-planet systems without hot Jupiters should be preferentially aligned. What new research reveals is quite different.

Using data from the NASA's Kepler space telescope, an international research team led by Daniel Huber, a NASA Postdoctoral Program fellow at NASA's Ames Research Center in Moffett Field, Calif., studied Kepler-56, a red giant star four times larger than the sun located at a distance of approximately 3,000 light years from Earth. By analyzing the fluctuations in brightness at different points on the surface of Kepler-56, Huber and his collaborators discovered that the star's rotation axis is tilted by about 45 degrees to our line of sight.

"This was a surprise because we already knew about the existence of two planets transiting in front of Kepler-56. This suggested that the host star must be misaligned with the orbits of both planets," explains Huber. "What we found is quite literally a giant misalignment in an exoplanet system."

The culprit for the misalignment is suspected to be a third, massive companion in a long period orbit, revealed by observations obtained with the Keck telescope on Mauna Kea, Hawaii.

"Computer calculations show the outer companion may have torqued the orbital planes of the transiting planets in concert, leaving them co-planar but periodically misaligning them with the equator of the host star," said Daniel Fabrycky, co-author and professor of astronomy at the University of Chicago.

Nearly 20 years after the discovery of the first hot Jupiter, the giant misalignment in the Kepler-56 system marks an important step towards a unified explanation for the formation of hot Jupiters.

"We now know 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."

The results are published in the Oct. 18 issue of the journal Science. To download the paper see: Stellar Spin-Orbit Misalignment in a Multiplanet System (Huber et al, 2013).

The Planets
From tiny Mercury to distant Neptune and Pluto, The Planets profiles each of the Solar System's members in depth, featuring the latest imagery from space missions. The tallest mountains, the deepest canyons, the strongest winds, raging atmospheric storms, terrain studded with craters and vast worlds of ice are just some of the sights you'll see on this 100-page tour of the planets.
 GET YOUR COPY

Hubble Reborn
Hubble Reborn takes the reader on a journey through the Universe with spectacular full-colour pictures of galaxies, nebulae, planets and stars as seen through Hubble's eyes, along the way telling the dramatic story of the space telescope, including interviews with key scientists and astronauts.
 GET YOUR COPY

3D Universe
Witness the most awesome sights of the Universe as they were meant to be seen in this 100-page extravaganza of planets, galaxies and star-scapes, all in 3D!
 GET YOUR COPY


HOME | NEWS ARCHIVE | MAGAZINE | SOLAR SYSTEM | SKY CHART | RESOURCES | STORE | SPACEFLIGHT NOW

© 2014 Pole Star Publications Ltd.