AB Aurigae is a very young star 520 light-years away. Observations of this system in 2017 revealed a curious spiral pattern in the disk of material that surrounds it. Now, a new study has been able to zoom in on that feature, and astronomers think that a forming planet is the cause of the peculiar structure. According to the researchers, this could be the first direct evidence of a baby planet forming.
The team likens the baby planet to a boat on a lake; as it goes around, it leaves a wake in the gas disk. But the planet is also capturing some of that gas, creating a spiral pattern and, in particular, a weird "twist". These peculiar strands of gas all reaching towards the same region point strongly at the presence of an unseen planet. Their findings are reported in Astronomy & Astrophysics.
If the planet is there, it would be as far from AB Aurigae as Neptune is from the Sun, roughly 4.5 billion kilometers (2.8 billion miles). The observations build on the observations from 2017 by the Atacama Large Millimeter/submillimeter Array (ALMA) but goes deeper thanks to the more sophisticated capabilities of the European Southern Observatory’s (ESO) Very Large Telescope, providing important clues on planetary formation.
“We need to observe very young systems to really capture the moment when planets form,” lead author Anthony Boccaletti from the Observatoire de Paris said in a statement. “Thousands of exoplanets have been identified so far, but little is known about how they form.”
ALMA had seen the inner spiral arm but thanks to the new observations, both the inner spiral and the twist were visible, which is very important, as they corroborate some current ideas on how planets might be born.
"The twist is expected from some theoretical models of planet formation,” said co-author 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's Extremely Large Telescope, the world's biggest "eye in the sky", which is being built in Chile right now, will have the capability to see this system even more in-depth and may be able to confirm if a baby planet really is coming into existence.