Newspaper article The Christian Science Monitor

White Dwarf Star: A New Form of 'Cosmic Particle Accelerator'?

Newspaper article The Christian Science Monitor

White Dwarf Star: A New Form of 'Cosmic Particle Accelerator'?

Article excerpt

Although the night sky may at times seem painted still, many stars are constantly pulsing. The brightness of these variable stars changes over time due to a variety of possible processes: expansion and shrinking, eclipsing, even the sharing of mass. That is why members of the American Association of Variable Star Observers (AAVSO) dedicate their curiosity to variable stars. There's still so much astronomers don't know.

That curiosity is why a once little-known binary star in the Scorpius constellation is now big news. When Tom Marsh, lead author of a study published in Nature on Thursday and leader of the Astronomy & Astrophysics group in the department of physics at the University of Warwick, England, was first sent observations about AR Scorpii, the light curve didn't look very unusual to him.

But when he saw the large variation in brightness in the light curve, he "realized there was something odd about it," Professor Marsh tells The Christian Science Monitor in a phone interview. "That's what made me decide to look at it with a high-speed camera": a telescope with a four-meter aperture.

Once Marsh looked at the AR Scorpii under the telescope, he realized it was something entirely different from anything he'd seen before. When the star was first discovered in 1971, it was classified as a lone variable star that expands and contracts, and was promptly forgotten.

Upon closer observation, Marsh and his colleagues found that it was actually a binary star made up of both a white dwarf, the collapsed remains of a star that ran out of fuel, and a red dwarf, which is similar to Earth's sun, but smaller.

In an 'Aha!' moment, the researchers realized they were witnessing the cooler red dwarf moving away from them and coming toward them as it orbited the white dwarf.

The white dwarf, however, is the "star" of the system. "It's got the most incredibly strong pulsations that I've ever seen in any star. It can get four or five times stronger within 30 seconds and then fade away again and keep doing that."

Marsh calls it a "new type of cosmic particle accelerator."

What's more, it emits light at almost all wavelengths, Marsh says. "It even pulses in the radio. …

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