October 7, 2015: Though astronomers have discovered thousands of planets orbiting other
stars, very little is known about how they are born. The conventional wisdom is
that planets coagulate inside a vast disk of gas and dust encircling newborn stars.
But the details of the process are not well understood because it takes millions of
years to happen as the disk undergoes numerous changes until it finally
The young, nearby star AU Microscopii (AU Mic) is an ideal candidate to get a snapshot of planet birthing because the disk is tilted nearly edge on to our view from Earth. This very oblique perspective offers an opportunity to see structure in the disk that otherwise might go unnoticed. Astronomers are surprised to uncover fast-moving, wave-like features embedded in the disk that are unlike anything ever observed, or even predicted. Whatever they are, these ripples are moving at 22,000 miles per hour — fast enough to escape the star's gravitational pull. This parade of blob-like features stretches farther from the star than Pluto is from our sun. They are so mysterious it's not known if they are somehow associated with planet formation, or some unimagined, bizarre activity inside the disk.
Learn even more about AU Mic by joining the live Hubble Hangout discussion at 3:00 pm EDT on Thurs., Oct. 8 at http://hbbl.us/y6M.