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TW Hydra

April 25, 2011

The constellation Hydra, the water snake, undulates across most of the southern sky tonight. In fact, it's the largest constellation of all, but it's so faint you probably won't notice it.

Hydra's the home of a star that once seemed to be nothing special, but that today plays an important role in the study of young stars. It's called TW Hydra, and it's 175 light-years away.

Over the decades, astronomers slowly realized that TW Hydra is only about 10 million years old, compared to about four and a half billion years for the Sun. The star is so young that it may still be giving birth to planets.

Normally, young stars reside with other young stars in vast clouds of gas and dust -- the nurseries that gave them birth. The famous Orion Nebula, for example, houses thousands of newborn stars. But TW Hydra seemed to be alone.

Over the past couple of decades, though, astronomers noticed other young stars scattered around TW Hydra and sharing its motion through space. Like the stars of the Orion Nebula, they're all siblings -- they were born from the same nursery.

Although the stars are young, they're older than the stars in the Orion Nebula, so the gas and dust that gave birth to them have largely dispersed. That makes the connection between them less obvious, but no less real. And the group is much closer to Earth than the Orion Nebula is, so it's easier for astronomers to study the early stages of a star's life in this newfound family of stars.


Script by Ken Croswell, Copyright 2011


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