Most planetary systems 'flatter than pancakes,' astronomers discover

October 22, 2012, University of California, Los Angeles

(—Our solar system looks like many others, "flatter than pancakes," report UCLA astronomers who were able to statistically determine the properties of planetary systems using the latest data from NASA's Kepler space telescope.

The number of around other stars discovered so far by Kepler is more than three times the current number of such planets found by other means, notes UCLA graduate student Julia Fang, lead author of a new study that uses data from Kepler as a laboratory to study the typical number of planets in each and the degree of flatness of .

In new research submitted to the , Fang and UCLA professor Jean-Luc Margot developed detailed computer models of planetary systems and compared them to the properties of Kepler data. Their results reveal very flat orbits: more than 85 percent of planets have inclinations of less than three degrees.

The scientists examined the trajectories of planets around their and found that the trajectories are very closely aligned in a pancake-like geometry, much like the planets in our own solar system. These very flat orbits imply low relative inclinations with planets all orbiting near the same plane, Fang said.

"Next time you eat a thin-crust pizza, you can get a sense of the flatness of a typical planetary system," Margot said.

"We find it thrilling how flat and aligned these planetary systems are," Fang said.

An important motivation for the study was to compare the properties of these Kepler planetary systems to the solar system and to determine how typical the solar system is, said Margot, UCLA associate professor in the departments of Earth and Space Sciences, and of Physics and Astronomy. Seven out of the eight planets in our solar system have inclinations less than three degrees, with Mercury as the exception.

"It looks like our results are consistent with the flatness also evident in the planetary orbits in our solar system," Fang said. "Our may be common compared to other planetary systems in this regard. Perhaps we're not that special."

"I made pancakes this weekend to verify our analogy," Margot said. "I measured a mean thickness of 7.3 mm (a little under 1/4 inch) and a mean radius of 65 mm (about 2.5 inches). This corresponds to inclinations of six degrees. So most planetary systems are flatter than pancakes, by about a factor of two. The best mental image for the geometry of planetary systems is somewhere between a crepe and a pancake."

The team's intricate models of planetary systems also yielded the typical numbers of planets per planetary system.

For orbital periods out to 200 days, about 75 percent of systems have one or two planets, Fang said.

As additional data from the Kepler mission streams in, the scientists will be able to extend their study to longer orbital periods.

For planetary astronomers, the launch of Kepler and its ground-breaking discoveries has ushered in a golden era of exoplanet science.

"Kepler is an amazing telescope in space; so far it has discovered a treasure trove of planets totaling more than 2,300 candidates," Fang said.

The Kepler stares at more than 100,000 stars for glimpses of planets crossing in front of the stars, thus blocking off some of the starlight. This is akin to staring at more than 100,000 car headlights a few miles away to look for the dimming due to a mosquito crawling across the headlight, Fang said.

"Our study has begun finding answers to fundamentally important questions in planetary astronomy," Fang said. "We'll be presenting exciting results at upcoming conferences."

Fang, a doctoral candidate, and Margot will continue to study the haul of discovered by Kepler to learn more about their interesting dynamical properties.

Explore further: 41 new transiting planets in Kepler field of view

More information: "Architecture of Planetary Systems Based on Kepler Data: Number of Planets and Coplanarity" by Julia Fang and Jean-Luc Margot, submitted to the Astrophysical Journal. Preprint:

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1 / 5 (6) Oct 22, 2012
Re: Our solar system may be common compared to other planetary systems in this regard. Perhaps we're not that special.

At least from the press release, it's not clear that this conclusion is possible from the research. Have the researchers tried to also identify linear filamentary planetary systems within Herbig-Haro's? After all, filaments are extraordinarily common in space. Within plasma-based cosmologies, these filaments are the primary physical mechanism by which energy is transferred throughout the universe. The notion that they are simply shockwaves is undermined by Gerrit Verschuur's apparent observation of knots and critical ionization velocities affiliated with those knots. That seems to suggest that the cosmic filaments are like the filaments of novelty plasma globes, for CIV's are what one gets when charged particles are slammed into neutral gases at extraordinary velocities.
1 / 5 (6) Oct 23, 2012
Perhaps the authors should relate how their interest ties up with the ruling paradigm for planetary formation.
This should then raise the alarming red flag of why there exists ANY kind of deviation from the proverbial ultra-flat pancake in the first place.
Furthermore, it would be instructive to explain why our sun is inclined 7 degrees to the ecliptic.
Where/how does such an incredibly large deviation arise from?
not rated yet Oct 24, 2012
Have the researchers tried to also identify linear filamentary planetary systems within Herbig-Haro's?

The researchers conducted a study of the Kepler results. Are Herbig-Haro objects included in the targets Kepler is monitoring? No? Then they won't be included in this study either.

Your comment has no obvious relation to the article, it seems to be just a random "mission" post on your pet subject.

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