Exoplanet Kepler 22b | | | | | |
| | | | | | |  Automatic translation | | | | | | Kepler 22b | | | | Category : exoplanets |  | | | | | On December 6, 2011, NASA confirmed the discovery of the first planet located in the "habitable zone", its star.
The Kepler 22b exoplanet is in a region where liquid water could exist on the surface of a planet.
Kepler-22b, is the smallest of the planets found in the middle of the habitable zone of a star like our Sun.
The small planet about 2.4 times the radius of the Earth. Scientists do not yet know whether Kepler-22b has an essentially rocky composition, entirely gas or liquid, but its discovery is a step in the search for planets similar to Earth.
Kepler had already discovered more than 1 000 new planetary candidates.
Ten of these candidates have a size similar to that of the Earth and its orbit is in the habitable zone of their host star.
Candidates require special monitoring to ensure that they are terrestrial planets.
Two other small planets orbiting stars smaller and cooler than our Sun, have recently been confirmed on the edge of a habitable zone, with orbits more like those of Venus and Mars. | | "This is an important step on the path that will allow us to find an Earth twin," said Douglas Hudgins, Kepler program scientist at NASA.
"The results of Kepler continue to demonstrate the importance of NASA's science missions, which aim to address some of the biggest questions about our place in the universe."
Since March 6, 2009, the date of its launch, the Kepler telescope looks for exoplanets by measuring occultation luminosity of more than 150,000 stars in the Milky Way, rather than in regions of the constellations of Cygnus and Lyra.
This monster of Technology NASA sees large, since it is equipped with a photometer to measure the brightness of tens of thousands of stars simultaneously, to increase the chances of discovery by the transit method.
nota : A transit occurs each time the planet passes between its star and the observer, at that time, the planet obscures some of the light from the star, producing a detectable periodic dimming. Kepler needs at least three transits to check a signal such as a planet. | |   * This image compares the artist's kepler 22 solar system with our own solar system. The two stars have comparable sizes. The exoplanet Kepler-22b is ideally placed in an orbit, it is in the habitable zone of its star. | | | | | | | | Luck has smiled | | | | | | | | | | "Luck has smiled for the detection of this planet," said William Borucki, principal investigator at NASA (Ames Research Center at Moffett Field, California), he led the team that discovered Kepler-22b.
"The first transit was captured just three days after giving the probe operation. We have seen the third transit during the 2010 holiday season."
The Kepler science team uses ground-based telescopes and the Spitzer Space Telescope to observe the planet candidates found that the probe.
The star field that Kepler observes in the constellation Cygnus and Lyra, can be seen from ground-based observatories.
Kepler-22b is located 600 light-years. Although this planet is larger than the Earth's orbit, 290 days around a star like the sun, like ours.
The host star of Kepler 22b belongs to the same class as our Sun, G-type, although it is slightly smaller and cooler. The Kepler team at its inaugural conference of the 5 to 9 December 2011, announced 1,094 new discoveries of planets candidates. Since the last catalog was issued in February, the number of candidates identified by Kepler increased by 89% and now stands at 2326. | | Of these, 207 are about the size of the Earth, 680 are super Earths, 1181 are about the size of Neptune, 203 are Jupiter-sized and 55 are larger than Jupiter.
Since Kepler observes the many planets in orbit around their sun, it seems that the planets, one to four times the size of the Earth are abundant in the galaxy.
The number of Exoterra ie the size of Earth and super Earths candidates has increased by over 200% and 140% since February 2011.
Kepler 22b is the first planet that NASA's Kepler mission confirmed as being located in an orbit in the habitable zone of a star.
The habitable zone around a star allows water to exist in liquid form, a requirement for life to continue.
The planet Kepler 22b is 2.4 times the size of Earth, making it the smallest ever found in an orbit in the middle of a habitable zone of a star like our sun. | |  * Scientists do not yet know if the planet has a predominantly rocky an entirely gaseous or liquid composition. But it is possible that the atmosphere there is this world of clouds, as shown here in this artist's interpretation. Credit: NASA / Ames / JPL-Caltech. | | | | | | | | The proper place to live near the stars | | | | | | | | | | The circumstellar habitable zone is a sphere or ecosphere theoretical surrounding a star where the temperature at the surface of planets in orbit, would the appearance of liquid water. Scientists believe that liquid water is vital because of its role in biochemical reactions. Frank Drake calculated the distance from this area in its equation of 1961.
This equation takes into account the size, brightness of the star and the luminosity of the Sun. A star that has 25% of the luminosity of the Sun, will have a habitable zone centered at about 0.50 AU.
A star that has twice the brightness of the Sun, will have a habitable zone centered at 1.41 AU. A habitable zone (ZH) does not mean it houses within its life, but there is a possibility depending on many factors other than a terrestrial planet to harbor life: the Earth is home life, but the Moon located in the same area, is sterile.
The planet candidate in the development of life, must be massive enough to prevent water from escaping. The habitable zone is not a static area, it changes depending on the temperature of the star, as their evolution during the star becoming brighter and hotter and hotter, the habitable zone moves logically from the star. A planet will therefore remain as long as possible in this area, to develop all the molecules necessary for life form. | | We must not, in determining the habitability of a planet, put all the conditions that met our Earth, if no other planet in the universe could support life there, each planet is unique.
Only the condition of having liquid water seems necessary, it is considered an essential element to a viable ecosystem because it helps tremendously transporting materials necessary for biochemical activity. Water is a perfect piece to dissolve the materials and stores well the chemical elements.
Life can be present outside the habitable zone, just that there is liquid water, a source of energy and chemicals whose life needs to build its materials.
Astrobiologists believe that some life forms may exist on other objects in our solar system like Europa, a moon of Jupiter Galilean at 500 million km from Earth. Europe is a ball covered with ice the size of our Moon and has a sea of tens of km deep, kept liquid by the energy of tidal forces of Jupiter.
The friction caused by this stretching causes sufficient heat to maintain liquid water below the frozen surface. The discovery of exoplanets began in 1990 and 2010, 490 exoplanets were referenced. A terrestrial planet orbiting the star Gliese 581, a red dwarf star located 20.5 light years, lies in the habitable zone of the system. | |  * The ecosphere or habitable zone of a solar system based on its brightness and its mass.
Life can still be present outside the habitable zone, just that there's liquid water, a source of energy and chemicals whose life needs to build its materials. |
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| Astronomy - December 6, 2011 |
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