The orbits of exoplanets

Oct 25, 2011
An image of the dusty disk around Fomalhaut, with its planet, Fomalhaut-b, seen in the insert (at two different epochs). The orbit of the planet is less circular than the Earth's orbit. A new paper analyzes the probable orbital character of transiting exoplanets. Credit: NASA, ESA, and P. Kalas (University of California, Berkeley)

(PhysOrg.com) -- An exoplanet is a planet orbiting a star other than our sun.

As of this week, the exoplanet encyclopedia website lists 694 confirmed planets around other stars. Most of them have numerous physical parameters reasonably well determined, such as planetary mass and size of the orbit. One important parameter is the of an orbit, a measure of how non-circular it is; a circular orbit has an eccentricity of zero, while the maximum eccentricity is one.

In our , for example, the Earth's eccentricity is 0.017 (almost a perfect circle), and the largest planetary eccentricity is Mercury's, 0.206. Since the eccentricity in part determines how the of a planet varies over its year, it is a critical parameter for inferring whether possible on an exoplanet surface (non has yet been discovered) could stay liquid over its whole year.

In striking contrast to solar system planets, studies of have found that most have large eccentricities, many greater than 0.3. The Kepler satellite has detected over a thousand exoplanets (or candidate exoplanets) so far using the transit technique (i.e., seeing the starlight dim as the planet passes across the face of the star). Obtaining the orbital parameters of transiting exoplanets, however, is not as easy as with other techniques. Nevertheless, models can analyze the statistical behavior of the transits and infer general characteristics.

CfA astronomers Matt Holman, Samuel Quinn, Darin Ragozzine, and Guillermo Torres joined with colleagues on the Kepler science team to estimate the eccentricities of exoplanets around stars slightly cooler than the sun. With some fairly general assumptions, they find an average eccentricity is probably somewhat larger than Mercury's in our solar system, and with extreme values on either end (close to zero or to one) unlikely. The new results, which will refined as more data are collected and analyzed, are important not only for their implications about habitable planets, but because they will help astronomers better how planets form and settle into their stable orbits.

Explore further: Quest for extraterrestrial life not over, experts say

add to favorites email to friend print save as pdf

Related Stories

An exoplanet orbiting a double star

Oct 03, 2011

(PhysOrg.com) -- The Kepler satellite, which has now reported the detection of 1781 candidate exoplanets (a planet around a star other than the sun), has also discovered that at least one of them orbits a ...

Habitable zones

Aug 22, 2011

(PhysOrg.com) -- The "habitable zone" is the region around a star where a suitable planet could sustain the conditions necessary for life. Most astronomers take it to be the region where the balance between ...

Exoplanetary systems

Jan 07, 2011

(PhysOrg.com) -- There are now about fifty stars known with more than one orbiting planet - they are the exoplanetary equivalents of the solar system. These stellar families are critical to astronomers piecing ...

Kepler and the Search for Life in Our Galaxy

Sep 15, 2009

(PhysOrg.com) -- There are so many stars in our galaxy that even if planets with complex life (animals and plants) are rare - say one for every billion stars - there could still be dozens here in the Milky ...

Recommended for you

Quest for extraterrestrial life not over, experts say

Apr 18, 2014

The discovery of an Earth-sized planet in the "habitable" zone of a distant star, though exciting, is still a long way from pointing to the existence of extraterrestrial life, experts said Friday. ...

Continents may be a key feature of Super-Earths

Apr 18, 2014

Huge Earth-like planets that have both continents and oceans may be better at harboring extraterrestrial life than those that are water-only worlds. A new study gives hope for the possibility that many super-Earth ...

Exoplanets soon to gleam in the eye of NESSI

Apr 18, 2014

(Phys.org) —The New Mexico Exoplanet Spectroscopic Survey Instrument (NESSI) will soon get its first "taste" of exoplanets, helping astronomers decipher their chemical composition. Exoplanets are planets ...

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

omatumr
1 / 5 (8) Oct 25, 2011
It is important to remember that the first exoplanets discovered were rocky, Earth-like planets orbiting a pulsar [1,2].

Meteorites and planets also formed here from supernova debris orbiting a pulsar [3-5]

1. "A planetary system around the millisecond pulsar PSR1257 + 12", Nature 355, 145147 (1992)

2. "Confirmation of Earth Mass Planets Orbiting the Millisecond Pulsar PSR B1257+12". Science 264, 538542 (1994)

3. Origin of the Solar System

www.omatumr.com/Origin.htm

4. "Strange xenon, extinct super-heavy elements, and the solar neutrino puzzle", Science 195, 208-209 (1977)

www.omatumr.com/a...enon.pdf

5. "Isotopes tell Suns origin and operation", AIP Conference Proceedings 822, 206-225 (2006)

http://xxx.lanl.g.../0510001

With kind regards,
Oliver K. Manuel
jsdarkdestruction
1 / 5 (1) Oct 27, 2011
Oliver Manuel's recent efforts to plaster Physorg.com and other public news sites with his theories and personal URLs are a bit puzzling, as scientists have a variety of publications available to communicate directly to each other in. My best guess is that he is desperately trying to prop up his legacy in light of his arrest in his university office on 7 charges of rape and sodomy based on allegations by 4 of his own children. The charges have been reduced to one count of felony attempted sodomy, not necessarily because of his innocence, but because of the statute of limitations. One can only guess how the recent charges and decades of family strife have affected his ability to reason rationally and to remain objective while defending his unpopular theories.

http://mominer.ms...hildren/

http://www.homefa...uel.html

More news stories

NASA's space station Robonaut finally getting legs

Robonaut, the first out-of-this-world humanoid, is finally getting its space legs. For three years, Robonaut has had to manage from the waist up. This new pair of legs means the experimental robot—now stuck ...

Cosmologists weigh cosmic filaments and voids

(Phys.org) —Cosmologists have established that much of the stuff of the universe is made of dark matter, a mysterious, invisible substance that can't be directly detected but which exerts a gravitational ...

Ex-Apple chief plans mobile phone for India

Former Apple chief executive John Sculley, whose marketing skills helped bring the personal computer to desktops worldwide, says he plans to launch a mobile phone in India to exploit its still largely untapped ...

Filipino tests negative for Middle East virus

A Filipino nurse who tested positive for the Middle East virus has been found free of infection in a subsequent examination after he returned home, Philippine health officials said Saturday.

Egypt archaeologists find ancient writer's tomb

Egypt's minister of antiquities says a team of Spanish archaeologists has discovered two tombs in the southern part of the country, one of them belonging to a writer and containing a trove of artifacts including reed pens ...

Airbnb rental site raises $450 mn

Online lodging listings website Airbnb inked a $450 million funding deal with investors led by TPG, a source close to the matter said Friday.