* Astronomy

Members Login
Username 
 
Password 
    Remember Me  
Home -> Astronomy News -> Exoplanets -> Kepler-20
Post Info TOPIC: Kepler-20
Blobrana


L

Posts: 131433
Date:
RE: Kepler-20
Permalink  
 

Kepler-20 is a star 950 light-years from Earth in the constellation Lyra with a system of five known planets.
On December 20, 2011, the Kepler Space Telescope team reported the discovery of the first Earth-sized extrasolar planets, Kepler-20e and Kepler-20f, orbiting a Sun-like star. While the planets are Earth-sized, they are not Earth-like in other important respects: they are "nowhere near a habitable zone" according to the NASA report, with expected surface temperatures of 760 °C (1,400 °F) and 427 °C (801 °F), respectively. Both planets have orbits smaller than that of Mercury.
Read more



__________________
Blobrana


L

Posts: 131433
Date:
Kepler 20e and 20f
Permalink  
 

Two new Earth-sized exoplanets discovered

Hunting for habitable worlds, NASA's Kepler space telescope has unveiled two new planets, some 950 light-years away, that are the smallest yet detected, and the closest in size to Earth. In a paper published this week in Nature, scientists from MIT and elsewhere report that the planets - one just about Earth's size, and the other a bit smaller - likely have rocky compositions, similar to Earth, and orbit a star much like the sun. But that's where the similarities end.
Compared with Earth's leisurely 365-day orbit, the new planets practically whiz around their star in a matter of days or weeks. Their tight circuits, closer even than Mercury's orbit around our sun, make the planets extremely hot - likely too hot to sustain life. While either planet is far from Earth's twin, scientists say the discovery is a technological milestone.
Read more 



__________________
Blobrana


L

Posts: 131433
Date:
2MASSJ19104752+4220194
Permalink  
 

Title: Kepler-20: A Sun-like Star with Three Sub-Neptune Exoplanets and Two Earth-size Candidates
Authors: Thomas N. Gautier III, David Charbonneau, Jason F. Rowe, Geoffrey W. Marcy, Howard Isaacson, Guillermo Torres, Francois Fressin, Leslie A. Rogers, Jean-Michel Désert, Lars A. Buchhave, David W. Latham, Samuel N. Quinn, David R. Ciardi, Daniel C. Fabrycky, Eric B. Ford, Ronald L. Gilliland, Lucianne M. Walkowicz, Stephen T. Bryson, William D. Cochran, Michael Endl, Debra A. Fischer, Steve B. Howel, Elliott P. Horch, Thomas Barclay, Natalie Batalha, William J. Borucki, Jessie L. Christiansen, John C. Geary, Christopher E. Henze, Matthew J. Holman, Khadeejah Ibrahim, Jon M. Jenkins, Karen Kinemuchi, David G. Koch, Jack J. Lissauer, Dwight T. Sanderfer, Dimitar D. Sasselov, Sara Seager, Kathryn Silverio, Jeffrey C. Smith, Martin Still, Martin C. Stumpe, Peter Tenenbaum, Jeffrey Van Cleve

We present the discovery of the Kepler-20 planetary system, which we initially identified through the detection of five distinct periodic transit signals in the Kepler light curve of the host star 2MASSJ19104752+4220194. We find a stellar effective temperature Teff=5455+-100K, a metallicity of [Fe/H]=0.01+-0.04, and a surface gravity of log(g)=4.4 ±0.1. Combined with an estimate of the stellar density from the transit light curves we deduce a stellar mass of Mstar=0.912 ±0.034 Solar masses and a stellar radius of Rstar=0.944^{+0.060}_{-0.095} Rsun. For three of the transit signals, our results strongly disfavour the possibility that these result from astrophysical false positives. We conclude that the planetary scenario is more likely than that of an astrophysical false positive by a factor of 2e5 (Kepler-20b), 1e5 (Kepler-20c), and 1.1e3 (Kepler-20d), sufficient to validate these objects as planetary companions. For Kepler-20c and Kepler-20d, the blend scenario is independently disfavoured by the achromaticity of the transit: From Spitzer data gathered at 4.5um, we infer a ratio of the planetary to stellar radii of 0.075±0.015 (Kepler-20c) and 0.065 ±0.011 (Kepler-20d), consistent with each of the depths measured in the Kepler optical bandpass. We determine the orbital periods and physical radii of the three confirmed planets to be 3.70d and 1.91^{+0.12}_{-0.21} Earth radii for Kepler-20b, 10.85 d and 3.07^{+0.20}_{-0.31} Earth masses for Kepelr-20c, and 77.61 d and 2.75^{+0.17}_{-0.30} Earth radii for Kepler-20d. From multi-epoch radial velocities, we determine the masses of Kepler-20b and Kepler-20c to be 8.7\±2.2 Earth masses and 16.1 ±3.5 Earth radii, respectively, and we place an upper limit on the mass of Kepler-20d of 20.1 Earth masses (2 sigma).

Read more (3158kb, PDF)



__________________
Blobrana


L

Posts: 131433
Date:
RE: Kepler-20
Permalink  
 

Title: Two Earth-sized planets orbiting Kepler-20
Authors: Francois Fressin, Guillermo Torres, Jason F. Rowe, David Charbonneau, Leslie A. Rogers, Sarah Ballard, Natalie M. Batalha, William J. Borucki, Stephen T. Bryson, Lars A. Buchhave, David R. Ciardi, Jean-Michel Desert, Courtney D. Dressing, Daniel C. Fabrycky, Eric B. Ford, Thomas N. Gautier III, Christopher E. Henze, Matthew J. Holman, Andrew W. Howard, Steve B. Howell, Jon M. Jenkins, David G. Koch, David W. Latham, Jack J. Lissauer, Geoffrey W. Marcy, Samuel N. Quinn, Darin Ragozzine, Dimitar D. Sasselov, Sara Seager, Thomas Barclay, Fergal Mullally, Shawn E. Seader, Martin Still, Joseph D. Twicken, Susan E. Thompson, Kamal Uddin

Since the discovery of the first extrasolar giant planets around Sun-like stars, evolving observational capabilities have brought us closer to the detection of true Earth analogues. The size of an exoplanet can be determined when it periodically passes in front of (transits) its parent star, causing a decrease in starlight proportional to its radius. The smallest exoplanet hitherto discovered has a radius 1.42 times that of the Earth's radius (R Earth), and hence has 2.9 times its volume. Here we report the discovery of two planets, one Earth-sized (1.03R Earth) and the other smaller than the Earth (0.87R Earth), orbiting the star Kepler-20, which is already known to host three other, larger, transiting planets. The gravitational pull of the new planets on the parent star is too small to measure with current instrumentation. We apply a statistical method to show that the likelihood of the planetary interpretation of the transit signals is more than three orders of magnitude larger than that of the alternative hypothesis that the signals result from an eclipsing binary star. Theoretical considerations imply that these planets are rocky, with a composition of iron and silicate. The outer planet could have developed a thick water vapour atmosphere.

Read more (616kb, PDF)



__________________
Blobrana


L

Posts: 131433
Date:
Permalink  
 

This chart compares the first Earth-size planets found around a sun-like star to planets in our own solar system, Earth and Venus. NASA's Kepler mission discovered the new found planets, called Kepler-20e and Kepler-20f. Kepler-20e is slightly smaller than Venus with a radius .87 times that of Earth. Kepler-20f is a bit larger than Earth at 1.03 times the radius of Earth. Venus is very similar in size to Earth, with a radius of .95 times that our planet.
Read more 



__________________
Blobrana


L

Posts: 131433
Date:
Permalink  
 

Title: Two Earth-sized planets orbiting Kepler-20
Authors: Francois Fressin, Guillermo Torres, Jason F. Rowe, David Charbonneau, Leslie A. Rogers, Sarah Ballard, Natalie M. Batalha, William J. Borucki, Stephen T. Bryson, Lars A. Buchhave, David R. Ciardi, Jean-Michel Désert, Courtney D. Dressing, Daniel C. Fabrycky, Eric B. Ford, Thomas N. Gautier III, Christopher E. Henze, Matthew J. Holman, Andrew Howard, Steve B. Howell, Jon M. Jenkins, David G. Koch, David W. Latham, Jack J. Lissauer, Geoffrey W. Marcy et al.

Since the discovery of the first extrasolar giant planets around Sun-like stars1, 2, evolving observational capabilities have brought us closer to the detection of true Earth analogues. The size of an exoplanet can be determined when it periodically passes in front of (transits) its parent star, causing a decrease in starlight proportional to its radius. The smallest exoplanet hitherto discovered3 has a radius 1.42 times that of the Earth's radius (Earth radii plus), and hence has 2.9 times its volume. Here we report the discovery of two planets, one Earth-sized (1.03 Earth radii plus) and the other smaller than the Earth (0.87 Earth radii plus), orbiting the star Kepler-20, which is already known to host three other, larger, transiting planets4. The gravitational pull of the new planets on the parent star is too small to measure with current instrumentation. We apply a statistical method to show that the likelihood of the planetary interpretation of the transit signals is more than three orders of magnitude larger than that of the alternative hypothesis that the signals result from an eclipsing binary star. Theoretical considerations imply that these planets are rocky, with a composition of iron and silicate. The outer planet could have developed a thick water vapour atmosphere.

Source



__________________
Blobrana


L

Posts: 131433
Date:
Permalink  
 

Kepler Discovers First Earth-Sized Planets Outside Solar System



__________________
Blobrana


L

Posts: 131433
Date:
Kepler-20 system
Permalink  
 

Kepler-20 system



__________________
Blobrana


L

Posts: 131433
Date:
RE: Kepler-20e
Permalink  
 

First Earth-Sized Planets Found

Astronomers using NASA's Kepler mission have detected two Earth-sized planets orbiting a distant star. This discovery marks a milestone in the hunt for alien worlds, since it brings scientists one step closer to their ultimate goal of finding a twin Earth.
The two planets, dubbed Kepler-20e and 20f, are the smallest planets found to date. They have diameters of 6,900 miles and 8,200 miles - equivalent to 0.87 times Earth (slightly smaller than Venus) and 1.03 times Earth. These worlds are expected to have rocky compositions, so their masses should be less than 1.7 and 3 times Earth's.
Both worlds circle Kepler-20: a G-type star slightly cooler than the Sun and located 950 light-years from Earth. (It would take the space shuttle 36 million years to travel to Kepler-20.)
Read more 



__________________
Blobrana


L

Posts: 131433
Date:
Kepler-20f
Permalink  
 

NASA Discovers First Earth-Size Planets Beyond Our Solar System

NASA's Kepler mission has discovered the first Earth-size planets orbiting a sun-like star outside our solar system. The planets, called Kepler-20e and Kepler-20f, are too close to their star to be in the so-called habitable zone where liquid water could exist on a planet's surface, but they are the smallest exoplanets ever confirmed around a star like our sun.
The discovery marks the next important milestone in the ultimate search for planets like Earth. The new planets are thought to be rocky. Kepler-20e is slightly smaller than Venus, measuring 0.87 times the radius of Earth. Kepler-20f is slightly larger than Earth, measuring 1.03 times its radius. Both planets reside in a five-planet system called Kepler-20, approximately 1,000 light-years away in the constellation Lyra.
Read more 



__________________
1 2  >  Last»  | Page of 2  sorted by
 
Quick Reply

Please log in to post quick replies.
Home -> Astronomy News -> Exoplanets -> Kepler-20


Create your own FREE Forum
Report Abuse 		Powered by ActiveBoard