CXC: WASP-18: Planet Makes Star Act Deceptively Old

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CXC: WASP-18: Planet Makes Star Act Deceptively Old

Post by bystander » Tue Sep 16, 2014 5:46 pm

WASP-18: Chandra Finds Planet That Makes Star Act Deceptively Old
NASA | MSFC | SAO | Chandra X-ray Observatory | 2014 Sep 16
Image
Credit: X-ray: NASA/CXC/SAO/I. Pillitteri et al;
Optical: DSS; Illustration: NASA/CXC/M. Weiss
A new study using data from NASA's Chandra X-ray Observatory has shown that a planet is making the star that it orbits act much older than it actually is, as explained in our latest press release. The artist's illustration featured in the main part of this graphic depicts the star, WASP-18, and its planet, WASP-18b.

WASP-18b is a "hot Jupiter," a giant exoplanet that orbits very close to its star, located about 330 light years from Earth. Specifically, the mass of WASP-18b is estimated to be about ten times that of Jupiter, yet it orbits its star about once every 23 hours. By comparison, it takes Jupiter about 12 years to complete one trip around the Sun from its great distance.

The new Chandra data of the WASP-18 system show that this huge planet is so close to its star that it may be causing a dampening of the star's magnetic field. As stars age, their X-ray and magnetic activity decreases. Astronomers determined that WASP-18 is only between 500 million and 2 billion years old, a relatively young age for a star. Given this age, astronomers expect that WASP-18 would be giving off copious amounts of X-rays. ...

No X-rays from WASP-18. Implications for its age, activity, and the influence of its massive hot Jupiter - Ignazio Pillitteri et al
http://asterisk.apod.com/viewtopic.php?t=24890
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