Subscribe free to our newsletters via your
. 24/7 Space News .




EXO WORLDS
Kepler's Astounding Haul of Multiple-Planet Systems Just Keeps Growing
by Staff Writers
Boston MA (SPX) May 24, 2011


Kepler detects planets by monitoring a star's brightness very precisely. If a planet crosses the star's face from Kepler's point of view, the star will dim slightly in a specific way. Using this technique, Kepler has spotted more than 1,200 planetary candidates so far. Credit: NASA

NASA's Kepler spacecraft is proving itself to be a prolific planet hunter. Within just the first four months of data, astronomers have found evidence for more than 1,200 planetary candidates. Of those, 408 reside in systems containing two or more planets, and most of those look very different than our solar system.

In particular, the Kepler systems with multiple planets are much flatter than our solar system. They have to be for Kepler to spot them. Kepler watches for a planet to cross in front of its star, blocking a tiny fraction of the star's light. By measuring how much the star dims during such a transit, astronomers can calculate the planet's size, and by observing the time between successive events they can derive the orbital period - how long it takes the planet to revolve around its star.

To see a transit, the planet's orbit must be edge-on to our line of sight. To see multiple transiting planets, they all must be edge-on (or nearly so).

"We didn't anticipate that we would find so many multiple-transit systems. We thought we might see two or three. Instead, we found more than 100," said Smithsonian astronomer David Latham (Harvard-Smithsonian Center for Astrophysics).

Latham presented the findings in a press conference at the 218th meeting of the American Astronomical Society.

In our solar system, some planet orbits are tilted by up to 7 degrees, meaning that an alien astronomer looking for transits wouldn't be able to detect all eight planets. (In particular, they would miss Mercury and Venus.) The systems spotted by Kepler are much flatter, with orbits tilted less than 1 degree.

Why are they so flat? One clue comes from the planets themselves. The multiplanet systems found by Kepler are dominated by planets smaller than Neptune. They lack Jupiter-sized gas giants. Scientists believe that a gas giant's powerful gravity tends to disrupt planetary systems, tilting the orbits of neighboring worlds.

"Jupiters are the 800-pound gorillas stirring things up during the early history of these systems," explained Latham. "Other studies have found plenty of systems with big planets, but they're not flat."

Multiple-planet systems may offer a chance for confirming the densities of small, rocky worlds. The more massive a planet, the easier it is to detect using radial velocity measurements (essentially the star's wobble as a planet's gravity tugs it). Earth-sized worlds in Earth-sized orbits aren't massive enough to make a radial velocity signal that's detectable with present technology.

In systems with more than one transiting planet, astronomers have another option: transit timing variations. They can measure how the time between successive transits changes from orbit to orbit due to mutual gravitational interactions between the planets. The size of the effect depends on the planets' masses.

"These planets are pulling and pushing on each other, and we can measure that," said Smithsonian astronomer Matthew Holman. "Dozens of the systems Kepler found show signs of transit timing variations."

As Kepler continues to gather data, it will be able to spot planets with wider orbits, including some in the habitable zones of their stars. Transit timing variations may play a key role in confirming the first rocky planets with the right temperature for water to be liquid on their surfaces.

.


Related Links
Kepler at NASA
Lands Beyond Beyond - extra solar planets - news and science
Life Beyond Earth






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle








EXO WORLDS
Climate scientists reveal new candidate for first habitable exoplanet
Paris, France (SPX) May 23, 2011
The planetary system around the red dwarf Gliese 581, one of the closest stars to the Sun in the galaxy, has been the subject of several studies aiming to detect the first potentially habitable exoplanet. Two candidates have already been discarded, but a third planet, Gliese 581d, can be considered the first confirmed exoplanet that could support Earth-like life. This is the conclusion of ... read more


EXO WORLDS
Twin GRAIL Spacecraft to Launch Site by Lockheed Martin

A Wrinkly Old Reveal Clues To Its Past

MoonBots Challenges Teams to Conduct Lunar Missions with LEGO Robots

Earth's Nearest Neighbor Within Reach

EXO WORLDS
Endeavour Crater Just Three Miles Away For Opportunity Mars Rover

Mars Rover Driving Leaves Distinctive Tracks

Opportunity Cracks The 18-Mile Mark

Mars Science Laboratory Aeroshell Delivered To Launch Site

EXO WORLDS
Testing Spacesuits in Antarctica - Part 1

Which technologies get better faster

AIA Says US Human Spaceflight At Critical Juncture

NASA Denies Entry To Chinese Journalists For Shuttle Launch

EXO WORLDS
Top Chinese scientists honored with naming of minor planets

China sees smooth preparation for launch of unmanned module

China to attempt first space rendezvous

Countdown begins for Chineses space station program

EXO WORLDS
Expedition 27 Crew Undocks from Station

Astronauts to try spacewalk 'hokey pokey': NASA

ISS astronauts land safely in Kazakhstan: mission control

Pope makes first ever video call to astronauts in space

EXO WORLDS
Russia sends two Soyuz carrier rockets to French Guiana

ILS Proton Successfully Launches Telstar 14R And Estrela do Sul 2 for Telesat

Satellites for Asia and India are orbited on Arianespace's third Ariane 5 mission of 2011

Taiwan, Singapore launch satellite

EXO WORLDS
Kepler's Astounding Haul of Multiple-Planet Systems Just Keeps Growing

Bennett team discovers new class of extrasolar planets

Climate scientists reveal new candidate for first habitable exoplanet

Free-Floating Planets May be More Common Than Stars

EXO WORLDS
Long-delayed Duke Nukem videogame hits in June

Microsoft unveils Windows Phone update 'Mango'

Better buildings for extreme climates will be focus of researcher talk

Foxconn polishing plants in China closed after blast




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement