Unidentified Ripples Around Star Confound Astronomers

October 26, 2015 | Sarah Tse

Mysterious ripples around new star, AU Mciroscopii
Photo credit: ESO, NASA & ESA (CC BY 3.0)

Scientists are mystified by these never-before-seen waves surging through the dusty disc of a young star.

What are they? Gravitational waves? Supernova shock-waves? A burgeoning worm-hole? Astronomers have no idea what to make of these mysterious ripples streaking through the dust surrounding the young star AU Microscopii.

Since AU Mic is just a fledgling red dwarf and relatively close at 32 light-years away, astronomers have been keeping an eye on it for any signs of new planets coalescing from its thick, dusty disc. In 2014, they used the European Southern Observatory’s Spectro-Polarimetric High-contrast Exoplanet Research instrument, or SPHERE, to get a closer look at the star and were baffled by what they found. 

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Five dusty arches appeared to be spreading out from the star through its disc. Scientists have never before observed structures like these, and the team couldn’t think of a theory to explain their existence. It turns out that data from the Hubble Space Telescope taken in 2010 and 2011 not only showed the star’s entourage of ripples, but also recorded their movement over time.

Using the Hubble data, the astronomers tracked the ripples over a 4-year-period and discovered that they were shooting away from the star at breakneck speeds — up to 40,000 km/hr, which is fast enough for them to escape the star’s gravitational pull. This rules out any conventional explanations for what they are, because something fishy must be at work to give the ripples their velocity. The waves are too fast to be caused by budding planets, a collision between massive asteroids, or spiral waves forming out of a random instability in the star system’s gravity.

But the team believes one possibility may be AU Mic’s toddler tantrums. The star displays high flaring activity where it flings huge and unpredictable bursts of energy off its surface. If there are planets hidden in the stellar disc, such flares could jostle the planets and even tear off material that would drive the dusty ripples through space.

The diagnosis for these structures will have to wait until the team makes further observations with other instruments. Discovering such mysterious phenomena is a bit frustrating since astronomers have yet to even pin down all the cosmic objects predicted by physics theories, let alone completely new ones. But at least we can rest assured that the universe will never run out of wonders for us to investigate.

Check out a timelapse video of the mysterious ripples from the European Space Agency.

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