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[Maggie's blog] Bizarre Solar Systems at AAS

Apparently solar systems are also like a box of chocolates… As the saying goes, you never know what you’re going to get. At the recent American Astronomical Society (AAS) meeting in Austin, TX, I got to sit in on a press session on extrasolar planets, where three new systems were announced, each more bizarre than the next.

First was the announcement of the discovery of two new double-star planet systems found using Kepler data (Kepler-34 and Kepler-35). The first solar system similar to the fictional planet Tatooine from Star Wars (Kepler-16b) was actually discovered in 2011. It’s turning out that systems like the one containing Luke’s homeworld, which orbited twin suns, may be more common than previously thought.

William Welsh of San Diego State University and Kepler participating scientist who led the study said, “This work further establishes that such ‘two sun’ planets are not rare exceptions, but may in fact be common, with many millions existing in our galaxy. This discovery broadens the hunting ground for systems that could support life.”

The two newly discovered planets, named Kepler-34b and Kepler-35b, are both gaseous Saturn-size planets. Kepler-34b orbits its two sun-like stars every 289 days, and the stars orbit one another every 28 days. Kepler-35b orbits its smaller and cooler host stars every 131 days, and the stellar pair orbit each other every 21 days. The planets reside too close to their parent stars to be in the “habitable zone”- the region where liquid water could exist on a planet’s surface.
At 4,900 and 5,400 light-years from Earth, located in the constellation Cygnus, Kepler-34b and Kepler-35b are among the most distant planets discovered.

You can read more in this NASA release.

The next new solar system announced was one that is so tiny that it’s scale is more similar to Jupiter and its moons than to a star with planets:

Mini Planetary System
Credit: NASA/JPL-Caltech

Kepler and ground-based data was used to find this miniature system, called KOI-961, which has the three smallest exoplanets known so far to orbit a star other than our sun. The star is a red dwarf that is one-sixth the size of our Sun, located about 130 light years away in the Cygnus constellation.

The smallest of the three planets, KOI-961.03, is actually located the farthest from the star, and is shown in the foreground of the artist’s impression, shown above. This planet is about the same size as Mars, with a radius only 0.57 times that of Earth. To the upper right is KOI-961.01, which is 0.78 times the radius of Earth. Closest to the star is KOI-961.02, with a radius 0.73 times that of the Earth’s.

The planets all orbit very quickly around their star, all three of them in less than two days, and the closest planet in less than half a day. Since they are all so close to their star, all three planets are very hot (350 to 836 degrees Fahrenheit or 176 to 447 degrees Celsius) and well short of the habitable zone for this system.

There’s is more information and a larger image available in this NASA gallery.

The third newly-discovered solar system was, in the interest of full disclosure, found by a team led by an old college friend of mine, Dr. Eric Mamajek, of Rochester and the Cerro Tololo Inter-American Observatory. This system has a ring system that could be compared to that of Saturn.

Saturn-like Ring System Eclipsing a Sun-like Star
Credit: Michael Osadciw/University of Rochester

This team of astronomers has been using the data of small telescopes like SuperWASP and the All Sky Automated Survey to study the light curves (graphs of intensity of light over time) of young Sun-like stars in the Scorpius-Centaurus association, which is the nearest region of recent massive star formation to the Sun.

One star had a very unusual light curve that showed dramatic changes in its brightness during a 54-day period in 2007. After ruling out other things, the explanation remaining seemed to be that that light from that sun-like star was being transited by a smaller companion with a dust ring system.


Light Curve
Individual measurements of SuperWASP (top) and ASAS (bottom) V magnitudes for J1407 during early 2007. Credit: Mamajek et al

“This marks the first time astronomers have detected an extrasolar ring system transiting a Sun-like star, and the first system of discrete, thin, dust rings detected around a very low-mass object outside of our solar system,” said Mamajek, “But many questions remain about what exactly has been discovered.” He thinks the central object, companion to the sun-like star, is either a very low-mass star, a brown dwarf, or a large planet.

Along with learning more about this object, Mamajek’s team wants to know more about the two pronounced gaps in the rings, which could have been carved out by the formation of either planets (if the object is a star or brown dwarf) or moons (if the object is a giant planet).

You can read a complete account of this discovery on the University of Rochester’s website. You can also listen to the actual AAS press session audio. Click to Play

One of the commentators on the session, Dr. Virginia Trimble, said that with exoplanets, if it’s not forbidden, it’s compulsory. Essentially, if the laws of physics allow it, it’s probably out there somewhere. It’s exciting to think about all the interesting planets and planetary systems are waiting to be discovered!

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