Wednesday, October 27, 2010
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Two massive planets are similar to Jupiter orbiting two stars recently discovered extremely sisters close - an unexpected finding, since the disturbing gravitational effects in most binary star systems usually interrupt the formation of planets. extrasolar planets discovered in orbit around the binary system NN Serpentis, which is located at 1670 light years from Earth.
The most massive of the two white dwarf stars is very small - the exhausted remnant left behind when a star dies Sun-like star is about 2.3 times the diameter of Earth, but a temperature of more of 49,700 degrees Celsius - nearly nine times hotter than the Sun's surface
The other star is larger but cooler, with a mass only one-tenth of the Sun The two stars are bound in an orbit very close.
The Big
Astronomers had a lucky break to observe the binary star system, given that it be in the same plane as the Earth, creating an eclipse every 3 hours and 7 minutes when the star largest passes in front of the child.
The resulting change in the brightness of the system acts as a highly accurate clock. Monitoring the eclipses, the team of astronomers was able to detect small changes in timing caused by the gravitational pull of two planets orbiting a star partner, and pull them by altering the schedule of eclipses.
The system's largest planet is about 5.9 times more massive than Jupiter. Binary stars orbiting once every 15.5 years land within striking distance of some 900 million kilometers. Closer, the second planet orbiting the binary pair every 7.75 years is land and 1.6 times more massive than Jupiter.
An international team of astronomers detected the planetary system using a wide variety of observations taken over two decades from various ground-based telescopes.
Parents binary
Although the discovery of planets outside our solar system is becoming increasingly common, only a tiny fraction of those planets have been found orbiting stars in binary or multiple systems. This is simply because, in these systems, there is little space between the stars forming planets.
Both NN Serpentis planets do not orbit around the binary stars, but the double star system was not always as compact as today. Before, when the current white dwarf star was a normal, twice as massive as the Sun, the two stars was separated by a much greater distance - such observable eclipses that have occurred once every two years.
When the most massive star ended his normal life consumption of hydrogen in its core, is inflated to form a red giant and then absorbed a second star in its diffuse outer sheath. The friction of the companion star moving inside the shell of the red giant finally brought the red giant lost 75% of its mass.
This left only the intensely hot core of the original star and a companion star orbiting relatively harmless now extremely close to the newly formed white dwarf. The
turbulent change from a normal of a compact double star with a hot white dwarf would have been even more dramatic for any planets present beforehand: the loss of 75% of the original mass of the star equivalent to a 75% loss in gravitational force.
This could easily result in the release of planets, sending them speeding through space. Or, simply, could have ended in a dramatic change in the orbit of the planets.
Second option
In a different scenario, planets around NN Serpentis could have been created for only a million years, when issued large amounts of dust and gas from the star to form a more massive version of a protoplanetary disk. From this material, the planets may have formed. That being the case, then it is possible that these massive planets were born, in fact, after the death of the star that allowed its creation.
The study results are published on-line in a recent issue of the journal Astronomy & Astrophysics
.
In a separate discovery, has recently found a Jupiter-sized extrasolar planet orbiting the star HR 7162, which is a binary star located to 49 light years away in the constellation Lyra. These recent findings are forcing astronomers to rethink theories about how planets form gas giants.
Author: Space.com Template
Original Date: October 26, 2010 Original Link
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