Universe  ID: 12806

'Winking' Star May Be Devouring Wrecked Planets

Astronomers studying the star RZ Piscium have found evidence suggesting its strange, unpredictable dimming episodes may be caused by vast orbiting clouds of gas and dust, the remains of one or more destroyed planets.

Young stars are often prodigious X-ray sources. Observations using the European Space Agency's XMM-Newton satellite, show that RZ Piscium is, too. Its total X-ray output is roughly 1,000 times greater than our Sun's. Ground-based observations show the star's surface temperature to be about 9,600 degrees Fahrenheit (5,330 degrees Celsius), only slightly cooler than the Sun's. They also show RZ Piscium is enriched in the tell-tale element lithium, which is slowly destroyed by nuclear reactions inside stars and serves as a clock indicating the elapsed time since a star's birth.

Ground-based telescopes also reveal large amounts of dust and hydrogen-rich gas in the system, suggesting that large blobs of this material are orbiting the star and causing the brightness dips.

The best explanation that accounts for all of the available data, say the researchers, is that the star is encircled by debris representing the aftermath of a disaster of planetary proportions. It's possible the star's tides may be stripping material from a close substellar companion or giant planet, producing intermittent streams of gas and dust, or that the companion is already completely dissolved. Another possibility is that one or more massive gas-rich planets in the system underwent a catastrophic collision in the astronomically recent past.

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NASA's Goddard Space Flight Center