A stash of alien planets found hiding in a dusty region where stars form could help scientists trace our Solar System’s history.
Astronomers peered through the dust that fills a star-forming region just 450 light-years from Earth in the constellation Taurus, using the Atacama Large Millimeter/submillimeter Array observatory in Chile. They looked at 32 stars surrounded by protoplanetary discs. These discs, made up of dust and debris, are typically flat and uniform, spreading out around their star like a pancake. But 12 of them in this survey have gaps that can only be fully explained by the presence of planets forming around the stars.
The new stars are too bright for us to see any of their planets directly, so the researchers did some calculations to work out how big these likely planets were. While two discs could be harbouring planets up to gas giant Jupiter’s size, the rest are a maximum of 20 times the mass of Earth, making them either super-Earths or Neptune-like planets, depending on if they’re rocky or made of gas.
Over 4.5 billion years ago our own Solar System was a swirling disc of dust around the Sun. Astronomers use observations of other solar systems to test their theories about what happened when our own star and its planets formed.
The finding also backs up astronomers’ suspicions that super-Earths and Neptune-like planets are the most common outside of our Solar System. “This is fascinating because it is the first time that exoplanet statistics, which suggest that super-Earths and Neptunes are the most common type of planets, coincide with observations of protoplanetary discs,” said Feng Long, paper author and PhD student at Peking University in Beijing, China.