Elena Sabbi on vampire stars that munch on neighbors

In 2006, astronomers detected what they’re calling vampire stars hiding in a star cluster called 47 Tucanae, visible from Earth’s southern hemisphere.

The cluster is known to contain hundreds of thousands of densely-packed stars, thought to have formed at around the same time, 12 billion years ago. But some stars in 47 Tucanae look far younger.

These blue stragglers, as they’re called, exhibit a brightness and color that make them appear only 1 to 2 billion years old. Elena Sabbi of the Space Telescope Science Institute thinks these stars really are old, but appear young because they’ve been munching on neighboring stars.

Elena Sabbi: Stellar vampirism is just when a star can steal the evelope – the most external part – of a companion.

A vampire star feasts on its neighbor’s gases, said Dr. Sabbi, for example, hydrogen, carbon, and oxygen.

Elena Sabbi: The vampire becomes bigger, and so it has much material to burn inside. And this means that the nuclear burning can be more efficient, and the stars can become hotter and brighter. So as a consequence, it looks exactly like a young star.

In other words, even elderly stars can keep a youthful glow … if they devour their comrades.

Our thanks today to Research Corporation, a foundation for the advancement of science.

Our thanks to:
Elena Sabbi
Space Telescope Science Institute

December 16, 2006

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