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article imageAstronomers discover alien planets that survived death of star

By JohnThomas Didymus     Dec 22, 2011 in Science
Toulouse - Astronomers have discovered two alien planets that survived the red-giant phase of their star's life cycle. The find contradicts the widely held view that planets are scorched to death when their stars expand into red giants preparatory to extinction.
Space.com reports that the scientists were further surprised to find that the planets, KOI 55.01 and KOI 55.02, exacted a toll on their stars by stripping it of much of its mass. According to Stephane Charipinet of the Institut de Recherche en Astrophysique et Planétologie in Toulouse, France, who led the study: "To our knowledge, there has been no previous case reported where such a strong influence on the evolution of a star seems to have occurred."
The discovery of the planets was made while the team was studying a star called KIC 05807616 that was in the final stages of its life cycle, having moved away from the stable main-sequence. KIC 05807616 had already completed the red giant stage of death crisis in which the star, after using up its hydrogen thermonuclear fuel, expands in size, and in the process engulfs planets in its orbit. The star had shrunk in size into what astronomers called a hot B Subdwarf.
The team of scientists observed that the dwarf star gave periodic brightness variations recurring every 5.8 and 8.2 hours and from their studies they confirmed that the variations were caused by two small planets at close orbits around the star. According to Space.com, the Kepler telescopes uses a method called "transit method" to detect planets in orbit around a star, and this method involves detecting a dimming of lights when the planet passes across the front of a star as seen from the Earth. The astronomers were surprised that instead of observing a dimming they were observing light the planet was emitting. According to Eliza Kempton of the University of California, Santa Cruz,
"Light that is directly emitted or reflected from extrasolar planets has been detected in the past, but this is the first time that this particular method has been used for the discovery of a planetary system."
Discovery News reports the scientists believe that the two planets started off probably as Jupiter-size gas giants but when their star became a red giant and engulfed them they were caught in its gravitational field and plunged towards it. But being big planets, they were able to strip the star of atmospheric material while the star in turn stripped them of gaseous matter, leaving only the solid core which astronomers now observe.
Charpinet explained to Space.com that our Sun's big planets may be too far away to have the same effect on it when it reaches the red giant stage.
Studying dying stars and their planetary systems is of interest to astronomers because a similar fate is predicted for our solar system. It is expected that our star, the Sun, will become a red giant in about 5 billion years. Jerusalem Post reports that Steve Kawaler, professor of physics and astronomy at the Iowa State University, who was involved in the study, said: “This is a snapshot of what our solar system might look like after several billion more years of evolution. This can help us learn about the future of planetary systems and of our own sun.”
According to Discovery News , Eliza Kempton of the University of Southern California, said: "The expansion of the sun will surely kill off all life on Earth. However, the existence of planets orbiting an evolved star points to an interesting possibility that all close-in planets are not entirely destroyed during stellar evolution."
Scientists predict that in the process of expanding into a red giant, our Sun will engulf the inner terrestrial planets Mercury, Venus and Earth. But it is not expected that any of the three will strip mass from the Sun because they are too small to exact such effect on the Sun. It is also thought that the giant planets may be too far from the Sun to strip off its mass
The study was published in the Letters section of the Dec. 22 edition of the journal Nature.
More about alien planets, Kepler space telescope, Stephane Charpinet, Red giant
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