In October 2015, astronomers working with NASA's Hubble Space Telescope and the European Southern Observatory's (ESO) Very Large
Telescope located in Chile discovered never-before-seen features inside the
dusty disk surrounding the young, close by star AU Microscopii (AU Mic).They
discovered fast-moving, wave-like structures, which are unlike anything ever
observed before, or even anticipated in a circumstellar disk. This recent,
mysterious occurrence may deliver valuable hints about how planets are made inside
these star-surrounding disks.
AU Microscopii is situated 32 light-years away in
the southern constellation Microscopium. It is sort of an ideal star to observe
because its circumstellar disk is tilted edge-on to our sight from Planet Earth.
This allow for some details in the disk to be better observed. Astronomers have
been probing AU Mic's disk for any signs of bulky or warped features that can deliver
indication for planet formation. Instead, they discovered a very rare feature close
the star by using ESO's SPHERE (Spectro-Polarimetric High-contrast Exoplanet
Research) tool, mounted on the Very Large Telescope.
The images (below) disclose a sequence of
wave-like arches, like ripples in water. After noticing the features in the
SPHERE data the astronomers turned to previous Hubble imageries of the disk, captured
in 2010 and 2011. These features were not documented in the early Hubble
observations.
But once astronomers re-vised the Hubble pictures
they not only recognized the features but also grasped that they had changed
over time. The astronomers report that these ripples are actually moving -- and
they are moving rapidly.
The ripples farther away from the star appear to
be stirring faster than those nearer to it. However, three of the ripples are
moving so rapid that they are actually escaping from the gravitational
attraction of the star. Such high speeds exclude the likelihood that these ripples
are produced by objects, like planets, gravitationally distressing material in
the disk.
Astronomers has also ruled out a series of
phenomena as clarifications, counting the collision of two massive and uncommon
asteroid-like objects discharging large amounts of dust and spiral waves caused
by uncertainties in the system's gravity.
Astronomers decide to carry on to observe the AU
Mic system to try to comprehend what is really happening. But, for the time
being, these questioning features remain an unexplained mystery.
