Hot Jupiter exoplanet discovery sheds light on planetary systems
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Last Updated: Sunday, January 16, 2011, 18:33
Washington: New findings suggest that the discovery of a hot Jupiter exoplanet that transfers orbital momentum to its host star may hold the key to a clearer understanding of the evolution of common planetary systems.

According to Edward Guinan of Villanova University in Villanova, the discovery is of special interest because it represents a rare case in which a research team was able to make an independent age determination of the planet system by studying the system’s faint red dwarf companion star.

The discovery opens a new gateway to learning about the dynamics and evolution of many other planetary systems that also contain close-in hot-Jupiter type planets.

HD189733b, the Hot Jupiter exoplanet, orbits an orange (dwarf K) star HD18973A in the constellation Vulpecula (the Fox).

The loss in the planet’s orbital momentum in the past may explain why it orbits so close to their host stars. While the planet is spiraling in toward the star, and is most likely doomed, there is a possibility that the interacting magnetic fields of the star and planet could create a tidal-magnetically locked orbit-rotation that might allow the planet to survive.

The most likely scenario, however, is that the planet will draw closer to the star and its atmosphere will be eroded away by the star’s intense radiation and strong winds. The planet will ultimately be ripped apart by the star''s gravity if it survives the star’s radiation and winds.

HD 189733 Ab is a relatively rare eclipsing planetary system that was discovered in 2005 and has attracted much attention in astronomical circles because it hosts a transiting Hot Jupiter exoplanet.

The system is relatively bright. The eclipses by the planet permit substantial information to be gained from observing the system inside and outside the planetary eclipses.

The Villanova team found that this system is about over five billion years old and that the Jupiter-size planet has been estimated to be very hot at ~1,500 degrees Fahrenheit by other researchers.

"Planetary systems like HD 189733 with short period, "hot-Jupiter" planets are very common - over a hundred have been discovered so far," noted Guinan.

He continued, "HD 189733 and dozens of other planetary systems like it, many of which were recently discovered by NASA's Kepler mission, may also be undergoing the same process of strong magnetic interactions between their close-in large planets and their host stars."

"The big clue that is different here is that we know the age of HD 189733 from the study of its coeval faint companion star." This discovery should help in our endeavors to try to better understand the dynamics of other planetary systems like HD 189733," he added.

Of the over 500 exoplanets that have been discovered to date, HD 189733 is the only one of a handful whose age and physical properties have been well determined.

"This study may help explain how and why hot Jupiters form and evolve. It may help explain this whole class of planets," added Guinan.

The findings were detailed in a press conference held at the opening of the 217th American Astronomy Society meeting in Seattle, Washington. ANI

First Published: Sunday, January 16, 2011, 18:33

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