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Under construction 10:20:51 28/06/2005
Planetary zone found by TW Hydrae
Interstellar travellers might want to detour around the star system TW Hydrae to avoid a messy planetary construction site. Astronomer David Wilner of the Harvard-Smithsonian Center for Astrophysics (CfA) and his colleagues have discovered a massive planetary zone forming around the star system TW Hydrae. These rocky chunks, which extend outward for at least 1 billion miles, should continue to grow in size as they collide and stick together until they eventually form planets.
"We're seeing planet building happening right before our eyes," said Wilner. "The foundation has been laid and now the building materials are coming together to make a new solar system."
Wilner used the National Science Foundation's Very Large Array to measure radio emissions from TW Hydrae. He detected radiation from a cold, extended dust disk suffused with centimeter-sized pebbles. Such pebbles are a prerequisite for planet formation, created as dust collects together into larger and larger clumps. Over millions of years, those clumps grow into planets.
This is the first time astronomers have seen this intermediate stage, after pure dust, but before planets.
Located about 180 light-years away in the constellation Hydra the Water Snake, TW Hydrae consists of a 10 million-year-old star about four-fifths the size of the Sun. The protoplanetary disk surrounding TW Hydrae contains about one-tenth as much material as the Sun - more than enough to form one or more Jupiter-sized worlds.
"TW Hydrae is unique," said Wilner. "It's nearby, and it's just the right age to be forming planets. We'll be studying it for decades to come."
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