spacetoday.net: Astronomers detect exoplanet in x-rays

Posted: Wed, Jul 31, 2013, 8:12 AM ET (1212 GMT)
HD 189733b seen in x-rays (NASA)

Astronomers have detected an extrasolar planet for the first time using x-ray observations. Researchers used observations by NASA's Chandra X-ray Observatory and ESA's XMM-Newton spacecraft to attempt to detect an exoplanet already known to orbit the star HD 189733, 63 light-years from the Earth, as the planet transited the star's disk. Astronomers not only confirmed the planet's presence in those x-ray observations, they say three times the dimming of the star in x-rays as in visible light, suggesting that the exoplanet's atmosphere may contain extended layers that are transparent to visible light but opaque to x-rays.