Anne M Stark for LLNL News
Livermore, CA (SPX) Jan 13, 2012
There are more exoplanets further away from their parent stars than originally thought, according to new astrophysics research.
In a new paper appearing in the Jan. 12 edition of the journal, Nature, astrophysicist Kem Cook as part of an international collaboration, analyzed microlensing data that bridges the gap between a recent finding of planets further away from their parent stars and observations of planets extremely close to their parent star.
The results point to more planetary systems resembling our solar system rather than being significantly different.
Gravitational microlensing occurs when light from a source star is bent and focused by gravity as a second object (the lens star), which passes between the source star and an observer on Earth. A planet rotating around the lens star will produce an additional deviation in the microlensing.
The first gravitational microlensing observations were made by the Massive Astrophysical Compact Halo Object (MACHO) collaboration, led by Livermore scientists.
The new research also determines that a large fraction of planets have orbital distances from 0.5 to 10 sun-Earth distances. In the past, using the Doppler shift technique, most extrasolar planets found were gas giants like Jupiter and Saturn that orbited stars that were much closer to them than the sun is to Earth.
An exoplanet is a planet outside our solar system. Over the past 16 years, astronomers have detected more than 700 confirmed exoplanets and have started to probe the spectra and atmospheres of these worlds.
While studying the properties of individual exoplanets is undeniably valuable, a much more basic question remains: how commonplace are planets in the Milky Way?
The team found that approximately 17 percent of stars host Jupiter-mass planets. However, cool-Neptunes and super-Earths are more common, occurring 52 percent and 62 percent, respectively, of the time.
Gravitationally microlensing is very rare. In fact, fewer stars than one per million undergo micolensing at any time.
The team's result is consistent with every star of the Milky Way, hosting, on average, one planet or more in an orbital distance range of 0.5 to 10 sun-Earth distances.
"Our measurements confirm that low-mass planets are very common and the number of planets increases with decreasing planet mass, in an agreement with the predictions of the core accretion scenario of planet formation," Cook said. "Planets around stars in our galaxy appear to be the rule rather than the exception."
"We used to think that the Earth might be unique in our galaxy. But now it seems that there are literally billions of planets with masses similar to Earth orbiting stars in the Milky Way," concludes Daniel Kuba, of the European Southern Observatory and co-lead author of the paper.
Massive Compact Halo Objects (MACHO) project
Lands Beyond Beyond - extra solar planets - news and science
Life Beyond Earth
Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.
Milky Way teaming with 'billions' of planets: study
Paris (AFP) Jan 11, 2012
The Milky Way is home to far more planets than previously thought, boosting the odds that at least one of them may harbour life, according to a study released Wednesday. Not long ago, astronomers counted the number of "exoplanets" detected outside our own solar system in the teens, then in the hundreds. Today the tally stands at just over 700. But the new study, published in Nature, prov ... read more
|The content herein, unless otherwise known to be public domain, are Copyright 1995-2012 - Space Media Network. AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. 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|