Astronomers have found a baby planet hidden in clouds of gas and dust swirling within a young solar system, by studying the accumulation of material around Lagrange points.
That’s according to research published this week in The Astrophysical Journal Letters.
Studying these protoplanets is difficult. Their stellar nurseries are shrouded in thick, hot clumps of mostly hydrogen gas, preventing astronomers from clearly observing the birth of stars and planets.
“Directly detecting young planets is very challenging and has so far only been successful in one or two cases,” Feng Long, first author of the study and a postdoctoral fellow at the Center for Astrophysics at Harvard, said. “The planets are always too faint for us to see because they’re embedded in thick layers of gas and dust.”
To overcome this hurdle, Long and her colleagues developed a method to detect baby worlds, and used it to discover what appears to be a young planet forming around LkCa 15, a juvenile star located 518 light-years from Earth.
Here’s how the team said they did it. They used observational data gathered from the ALMA telescope, which revealed a clump of mass and an arc-shaped feature, both telltale signs that something else is forming within the dense protoplanetary disk of matter surrounding the young star.
These images did not, however, provide hard evidence of a planet forming around that sun. But another measurement connecting the pair of features convinced the team they had found an alien world in the making. “This arc and clump are separated by about 120 degrees,” Long said. “That degree of separation doesn’t just happen — it’s important mathematically.”
The separation showed these two features lie at Lagrange points, points in space around which objects can orbit stably thanks to the gravitational pull of two nearby large objects – for example, a star and a planet
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The data from LkCa 15 showed the arc is located at the L4 point and the clump is at L5. These are so placed because another object – a hidden planet – is orbiting between them; the Lagrange points are the result of the gravitational pull by the young star and its forming world, just as the Sun and Earth form Lagrange points
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Long and her colleagues used the data to simulate the growth of a planet with similar properties to the one they thought they had found, and compared their model’s results with the telescope’s images.
Strong similarities between the simulations and observational data showed a planet is likely forming around LkCa 15. The mystery object is estimated to be about the size of Neptune or Saturn, and orbits around the star at quite a distance – 42 times the distance between the Sun and Earth
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“[We] put a planet into a disk full of gas parcels and dust particles, and see how they interact and evolve under known physics,” […] This model image will show what the millimeter wavelength emission would look like, [so we can] make a direct comparison with our observations.”
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Source: Astronomers describe how they found a baby planet forming • The Register
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