Thursday, July 26, 2012

A Far-Out Solar System That Looks Like Ours

From far enough away,, our solar system looks 2-D. All eight planets still orbit on nearly the same horizontal plane, which matches up with the plane of the sun's equator. It?s what makes our home system look like a flat, spinning disc, and also a sign that our system hasn?t experienced anything too chaotic since its formation more than 4 billion years ago.

Until now, many astronomers thought that comparatively few star systems end up looking like ours. The planet-hunting Kepler telescope has spotted many systems in which the arrangement of worlds is askew rather than orderly. But now, thanks to new research being published in the journal Nature this week, scientists say there might be many more star systems that look like ours.

The three planets of a star now called Kepler-30 all appear to be in orbit around their star on the same horizontal plane, according to Roberto Sanchis-Ojeda, the lead author on the study and a Ph.D. candidate at MIT. "The physical conditions of the new system are such that it looks pretty much like our system."

Bumpy Beginnings


The birth of a solar system can be a messy process. The forming star?s gravitational pull attracts dust, gas, and rock that form a ring around the newborn. After billions of years, the chaotic ring eventually starts to differentiate itself into the component parts of what we recognize as a solar system.

Round planets and oddly shaped asteroids carve out their own orbits in the newly formed planetary neighborhood. But usually, Sanchis-Ojeda says, the results aren?t perfectly clean. Maybe a few planets scatter to one side or fall into a different orbit. Sometimes, if two planets form close together, the larger world?s gravitational forces can push the weaker out of orbit or off track. A rogue asteroid or comet could quite literally knock a planet out of whack.

Turbulence rocked our own solar system in its early days. For instance, the most likely explanation for the moon?s origin is that a Mars-size world struck the forming Earth, expelling the material that coalesced into our satellite. Nevertheless, the forces that wreaked havoc on solar systems around the galaxy early in their lives seem to have left ours relatively unscathed?despite the dangers, we wound up with eight planets on a horizontal plane.

Looks Like Home


Sanchis-Ojeda and his team were on a mission to find solar systems shaped like ours. The researchers used Kepler data to pick out certain star systems that fit within their parameters. Specifically, they wanted to study close young active stars with plenty of starspots (the equivalent of sunspots but on another star). These cooler areas on the surfaces of a star can act as markers for where a star is in its rotation; if you see the same starspot twice, you know the star has completed a revolution. Even though these spots fade with time, they stick around long enough to get a good read on the spin of a young star.

Sanchis-Ojeda saw three planets in the Kepler-30 system cross in front of, or transit, the same starspot?one right after the other. This meant that either the planets just happened to line up at that lucky moment before continuing their orbits on different geometric planes, or they were formed like our solar system?from a horizontal ring of gas and space dust. Sanchis-Ojeda hoped for the latter.

His confirmation came when the planet closest to the star transited the same starspot twice in the time Kepler had its eye on the system. The second transit all but affirms that the three planets didn?t just align by chance during their dissimilar orbits, he says?they must be on the same plane.

Kepler-30 is particularly important because its planets spin at an angle we can see from Earth. Our perspective and the placement of the relatively close solar system match up, making it easier to observe the transits. Kepler-30 is also quite close to the sun in mass and radius.

More Out There


Drake Deming, a professor of astronomy at the University of Maryland and author of a commentary accompanying the new study, says the researcher?s methods for tracking planetary orbits could eventually become a new standard for planet hunters, especially those looking for more solar systems like ours in the Universe.

Before Kepler, most of the exoplanets discovered were hot Jupiters?huge gaseous planets that were usually orbiting their stars in wildly oblique patterns. Astrophysicists know a lot about these "hot Jupiter" systems because they were relatively easy to study without space-based telescopes like Kepler.

But now researchers are finding more evidence that multiplanet systems such as ours are far more common than the solitary gas giants. "New studies have shown that indeed only one out of every 100 stars have a hot Jupiter," Sanchis-Ojeda says. "There are many more small planets close to a host star."

Although the Kepler-30 planets probably don?t hold life?all three are too close to their home star?they represent another step closer to finding a solar system that might, Deming says. The next step could be a new NASA program that, if funded in the fall, would take Sanchis-Ojeda?s methods even further. The Transiting Exoplanet Survey Satellite (TESS) is a Kepler-like satellite, but instead of focusing on a small sliver of the sky, TESS would survey the entire sky for nearby solar systems that could be similar to ours. "TESS would be an all-sky version of Kepler," Deming says. "We?ll have a better chance of finding nearby stars. It might be the future of exoplanetary science."

Source: http://www.popularmechanics.com/science/space/deep/a-far-out-solar-system-that-looks-like-ours-11016380?src=rss

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