Unicorns, Roses, and Star “Bells”–Oh, My!

It sounds like the start of a fairy tale: There’s a unicorn in outer space that holds a rose and a star that rings like a bell.

What I’m actually talking about is the constellation Monoceros, the Unicorn, a grouping of relatively faint stars huddled between Orion, Gemini, and Canis Major.

In addition to the main stars that give the constellation its shape, Monoceros houses a number of impressive objects visible via telescope—a triple star system that looks like a fixed triangle, a pair of binary stars that together weigh more than a hundred suns, and the colorful, star-forming Cone Nebula, to name a few.

Recently NASA’s Wide-field Infrared Explorer (WISE) space telescope captured this detailed picture of the Unicorn’s rose: the Rosette nebula, aka NGC 2237.
—Image courtesy NASA/JPL-Caltech/UCLA

The false-color composite shows starlight in shades of blue and the nebula’s warm gas and dust in red and green, as seen in four different infrared wavelengths.

At the rose’s heart sits a cluster of young stars called NGC 2244. The most massive of these stars produce huge amounts of ultraviolet radiation, which erode the nebula and sculpt it into its flowery form.

The whole shebang is visible through a backyard telescope. In fact, the star cluster was first spotted around 1690 by an English astronomer, and the surrounding nebula was identified about 150 years later.

Also this week, an international team using the French-led Convection Rotation and planetary Transits (CoRoT) satellite announced that they successfully listened in to the sound waves coming from a star in Monoceros called HD49933.

For the first time, the scientists were able to use these stellar sound waves to monitor starspots—patches of intense magnetic activity on the star’s surface, similar to sunspots.

What they found is that the distant star is going through a cycle of magnetic activity just like our sun’s 11-year cycle.

“Essentially, the star is ringing like a bell,” study co-author Travis Metcalfe, of the National Center for Atmospheric Research, said in a statement.

“As it moves through its starspot cycle, the tone and volume of the ringing changes in a very specific pattern, moving to higher tones with lower volume at the peak of its magnetic cycle.”

So far CoRoT has made its name largely as a planet hunter. The scope has found 14 stars that have at least one planet, and half of them are also in the Unicorn, including a star that hosts the “most Earthlike” planet yet found, dubbed CoRoT-7b.

CoRoT searches for planets via the transit method, which involves looking for dips in starlight as a body passes in front of the star.

But the probe was also designed to look for stellar oscillations that can reveal a star’s magnetic activity.

In our solar system, this magnetic cycle has plusses and minuses… stronger solar storms can trigger awesome auroras, but they can also spew radiation that can be damaging to astronauts, satellites, and even power grids.

(See pictures of auroras driven by a recent solar storm.)

Unlike the sun, the cycle for HD49933 seems to last less than a year, the shortest magnetic cycle yet observed on another star. But this difference could be a scientific boon.

In addition to offering a sort of sped-up view of what goes on with our sun, studies of more stars with short cycles could give insight into star cycles overall, which in turn sheds light on what makes a sunlike star a good place for hosting life as we know it.

“Understanding the activity of stars harboring planets is necessary, because magnetic conditions on the star’s surface could influence the habitable zone, where life could develop,” study lead author Rafael Garcia, of France’s Center for Nuclear Studies of Saclay, said in the statement.

In other words, variations in a star’s magnetic activity could affect the criteria for the so-called Goldilocks zone, the region around a star that’s “just right” for life to evolve on another Earthlike world.

How’s that for bringing the fairy tale full-circle?

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