Scientists find evidence of ‘baby’ planet in the making

“Directly detecting young planets is very challenging and has so far only been successful in one or two cases. The planets are always too faint for us to see because they’re embedded in thick layers of gas and dust,” said Feng Long, a postdoctoral fellow at the Center for Astrophysics who led the new study, in a press statement. Long is the first author of the research published in The Astrophysical Journal Letters.

Instead, scientists must hunt for clues that can help them infer that a planet is developing beneath the dust. “In the past few years, we’ve seen many structures pop up on disks that we think are caused by a planet’s presence, but it could be caused by something else, too. We need new techniques to look at and support that a planet is there,” added Wong.

Long began her research by re-examining a protoplanetary disk called LkCa 15, which is located about 518 light years away from our planet in the direction of the Taurus constellation. Scientists have previously used observations from the ALMA Observatory to report evidence of planet formation in the disk.

While examining high-resolution ALMA data of LkCa 15, Long discovered two faint features that were not reportedly previously—two separate and bright bunches of material orbiting withing the disk about 42 astronomical units away from the star at the centre. These bunches were in the shape of a small clump and a larger arc.

“This arc and clump are separated by about 120 degrees,” she says. “That degree of separation doesn’t just happen — it’s important mathematically. We’re seeing that this material is not just floating around freely, it’s stable and has a preference where it wants to be located based on physics and the objects involved,” explained Long.

In the disk, the arc and clump of material are located at the L4 and L5 Lagrange points. About 60 degrees between both is a small planet that is causing the accumulation of dust. Lagrange points are points in space where two bodies in motion, like a star and an orbiting planet, create regions of enhanced attraction where matter might accumulate. The results of the observations show a planet that is roughly the size of Neptune, and between one to three million years old, which is relatively young in planetary terms.

But directly imaging the small “baby” planet is not possible due to technology constraints but Long believes that further ALMA observations of LkCa 15 will provide added evidence that will support her discovery. Long is also hoping that the new approach for detecting young planets by searching for material accumulating at Lagrange points can be utilised by astronomers in the future.