Hallan dos planetas que orbitan alrededor de dos estrellas


Astrónomos de la Unión Astronómica Internacional han anunciado que la nave espacial Kleper ha descubierto el primer multisistema planetario circumbinario: dos planetas que orbitan alrededor de dos estrellas. El hallazgo ha sido publicado esta semana por la revista Science.

La nave espacial Kleper ha conseguido un nuevo descubrimiento, anunciado hoy por la Unión Astronómica Internacional (IAU, por sus siglas en inglés), que demuestra que los sistemas planetarios pueden formarse y sobrevivir incluso en un ambiente caótico alrededor de una estrella binaria.

El sistema, denominado Kepler-47, está formado por un par de estrellas que giran una alrededor de la otra cada 7,5 días.

El nuevo sistema planetario se encuentra a unos 5000 años-luz de distancia, en la constelación Cygnu

“Cada planeta transita alrededor de la estrella primaria, dando pruebas inequívocas de que los planetas son reales”, declaró Jerome Orosz, profesor asociado de astronomía en la Universidad Estatal de San Diego y autor principal del estudio.

La primera es similar al Sol, mientras que la segunda es una estrella diminuta 175 veces más débil.

El planeta interior tiene un diámetro tres veces más grande que el de la Tierra, convirtiéndolo en el planeta circumbinario en tránsito más pequeño conocido hasta el momento y que orbita a la pareja de estrellas cada 49 días.

Por su parte, el planeta exterior es ligeramente más grande que Urano y orbita cada 303 días. Su órbita se sitúa en la “zona habitable”, es decir, en la región alrededor de una estrella donde un planeta terrestre podría tener agua líquida en su superficie. Sin embargo, probablemente se trata de un planeta gigante gaseoso y por lo tanto no apto para la vida.

“Hemos aprendido que los planetas circumbinarios pueden ser como los planetas de nuestro propio Sistema Solar, pero con dos soles”, subraya Joshua Carter, coautor del estudio y miembro del Centro Harvard-Smithsoniano de Astrofísica.

El nuevo sistema planetario se encuentra a unos 5000 años-luz de distancia, en la constelación Cygnus.

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Referencia bibliográfica:

J. A. Orosz, et al. “Kepler-47: A Transiting Circumbinary Multi-planet System”. Science Express, 29 de agosto de 2012. doi/10.1126/science.1228380

Multiple Planets Orbiting Twin Suns
NASA’s Kepler mission has discovered the first transiting circumbinary system — multiple planets orbiting two suns — 4,900 light-years from Earth, in the constellation Cygnus, proving that more than one planets can form and survive in orbit around a binary star. The inner planet, Kepler-47b, orbits the pair of stars in less than 50 days. It is thought to be a sweltering world, where the destruction of methane in its super-heated atmosphere might lead to a thick haze that could blanket the planet. At three times the radius of Earth, Kepler-47b is the smallest known transiting circumbinary planet. The outer planet, Kepler-47c, orbits its host pair every 303 days, placing it in the so-called ‘habitable zone,’ the region in a planetary system where liquid water might exist on the surface of a planet. While not a world hospitable for life, Kepler-47c is thought to be a gaseous giant, slightly larger than Neptune, where an atmosphere of thick bright water clouds might exist.
Source Credit to : www.nasa.gov/

PASADENA, Calif. — The existence of a world with a double sunset, as portrayed in the film Star Wars more than 30 years ago, is now scientific fact. NASA’s Kepler mission has made the first unambiguous detection of a circumbinary planet — a planet orbiting two stars — 200 light-years from Earth.

Unlike Star Wars’ Tatooine, the planet is cold, gaseous and not thought to harbor life, but its discovery demonstrates the diversity of planets in our galaxy. Previous research has hinted at the existence of circumbinary planets, but clear confirmation proved elusive. Kepler detected such a planet, known as Kepler-16b, by observing transits, where the brightness of a parent star dims from the planet crossing in front of it.

“This discovery confirms a new class of planetary systems that could harbor life,” Kepler Principal Investigator William Borucki, of NASA’s Ames Research Center in Moffett Field, Calif., said. “Given that most stars in our galaxy are part of a binary system, this means the opportunities for life are much broader than if planets form only around single stars. This milestone discovery confirms a theory that scientists have had for decades but could not prove until now.”

A research team led by Laurance Doyle of the SETI Institute in Mountain View, Calif., used data from the Kepler space telescope, which measures dips in the brightness of more than 150,000 stars, to search for transiting planets. Kepler is the first NASA mission capable of finding Earth-size planets in or near the “habitable zone,” the region in a planetary system where liquid water can exist on the surface of the orbiting planet.

Scientists detected the new planet in the Kepler-16 system, a pair of orbiting stars that eclipse each other from our vantage point on Earth. When the smaller star partially blocks the larger star, a primary eclipse occurs, and a secondary eclipse occurs when the smaller star is occulted, or completely blocked, by the larger star.

Astronomers further observed that the brightness of the system dipped even when the stars were not eclipsing one another, hinting at a third body. The additional dimming in brightness events, called the tertiary and quaternary eclipses, reappeared at irregular intervals of time, indicating the stars were in different positions in their orbit each time the third body passed. This showed the third body was circling, not just one, but both stars, in a wide circumbinary orbit.

The gravitational tug on the stars, measured by changes in their eclipse times, was a good indicator of the mass of the third body. Only a very slight gravitational pull was detected, one that only could be caused by a small mass. The findings are described in a new study published Friday, Sept. 16, in the journal Science.

“Most of what we know about the sizes of stars comes from such eclipsing binary systems, and most of what we know about the size of planets comes from transits,” said Doyle, who also is the lead author and a Kepler participating scientist. “Kepler-16 combines the best of both worlds, with stellar eclipses and planetary transits in one system.”

This discovery confirms that Kepler-16b is an inhospitable, cold world about the size of Saturn and thought to be made up of about half rock and half gas. The parent stars are smaller than our sun. One is 69 percent the mass of the sun and the other only 20 percent. Kepler-16b orbits around both stars every 229 days, similar to Venus’ 225-day orbit, but lies outside the system’s habitable zone, where liquid water could exist on the surface, because the stars are cooler than our sun.

“Working in film, we often are tasked with creating something never before seen,” said visual effects supervisor John Knoll of Industrial Light & Magic, a division of Lucasfilm Ltd., in San Francisco. “However, more often than not, scientific discoveries prove to be more spectacular than anything we dare imagine. There is no doubt these discoveries influence and inspire storytellers. Their very existence serves as cause to dream bigger and open our minds to new possibilities beyond what we think we ‘know.'”

For more information about the Kepler mission and to view the digital press kit, visit:
http://www.nasa.gov/kepler

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