Images with a "twist" could be first showing birth of an exoplanet
An international team of astronomers led by Anthony Boccaletti of the Observatoire de Paris has found what may be the first images of a planet being born. Based on observations by the European Southern Observatory’s Very Large Telescope (ESO’s VLT), images of the young star AB Aurigae located 520 light-years away in the constellation of Auriga show a "twist" in the dust and gas cloud surrounding the star that indicate the presence of a planet being formed.
Though the dynamics of how planets form are still very poorly understood, the basic accepted mechanism is that planets are produced inside the clouds of gas and dust found around young stars. Over time, these clouds begin to clump and coalesce to form asteroids, comets, and, eventually, planets.
However, until now, no one has been able to see far enough into such a planet-forming cloud to understand the process.
Building on preliminary observations from the Atacama Large Millimeter/submillimeter Array (ALMA) that spotted two spiral arms of gas close to AB Aurigae, for the past year the ESO team probed deeper using the VLT's Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) instrument, which uses extreme adaptive optics to look at exoplanets and similar phenomena.
What the team found was a bright yellow twist in the cloud about as far away from the star as Neptune is from the Sun. Such a twist suggests the passage of the infant planet and has been compared to the wake of a boat on a lake.
"The twist is expected from some theoretical models of planet formation,” says team member Anne Dutrey. "It corresponds to the connection of two spirals – one winding inwards of the planet’s orbit, the other expanding outwards – which join at the planet location. They allow gas and dust from the disc to accrete onto the forming planet and make it grow."
ESO says that when it completes construction of the 39-m (128-ft) Extremely Large Telescope, which is planned for 2025, it expects to be able to see more details of the exoplanet's formation and the dynamics driving the process.
This research was published in Astronomy & Astrophysics.
The video below zooms in on AB Aurigae.