After a new star is born, the surrounding gas and dust flattens out into a rotating disk. Some of that matter will condense, eventually forming the planets that circle the star. Unfortunately, it is challenging to watch the formation of a new planet. Light from the star tends to drown out light from the planet. Astronomers have only been able to spot planet-like-objects in these disks a few times, and there has always been the possibility that what they spotted wasn’t a planet at all, just a feature of the disk.
Recently, two teams of scientists working with an instrument called SPHERE at the Very Large Telescope in Chile spotted a baby planet forming around a star about 370 light years away. To accomplish this discovery, the teams used a specialized instrument called a coronagraph. A coronagraph is attached to a telescope, and blots out light coming from the star, making it possible to capture light coming from the dimmer planets and features in the surrounding disk. The new planet has been named PDS 70b.
PDS 70b was observed by multiple instruments on multiple different nights, making the new data particularly exciting. If you superimposed the new planet with its star onto our solar system, PDS 70b would be around the location of Uranus and take about 120 years to orbit its sun. By measuring the visible and infrared light coming from the planet, astronomers were also able to estimate that the planet is approximately twice the size of Jupiter and much hotter, reaching about 1000oC at its surface.
The discovery is particularly exciting because it allows scientists an opportunity to observe the behavior of a newborn planet for the first time. Theories about planet formation can be tested against PDS 70b’s actual behavior to help us better understand how the universe works.
Managing correspondent: Emily Kerr
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Original science article: Discovery of a planetary-mass companion within the gap of the transition disk around PDS 70