By learning more about the young star system, scientists might be able to answer a few long-unanswered questions about how planets form, including the origins of Earth.
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Today, astronomers announce evidence of an exoplanet being born that could move us one step closer to understanding the process of planet formation around other stars. Specifically, LkCa 15 b, about 450 light years away and growing into something resembling the solar system’s very own Jupiter.
In this case, LkCa15 is approximately 2 million years old, but that’s comparatively young for a star, and recent enough for the system to still feature a circumstellar disk of debris capable of giving birth to new planets.
“The researchers’ discovery provides stringent constraints on planet-formation theories”, Zhaohuan Zhu of Princeton University, who was not affiliated with the new study, wrote in an accompanying “News & Views” piece in the same issue of Nature.
The photo provided the proof: “The difficulty had been that when you have indirect evidence, there are always alternate explanations that might fit the data”, Professor Tuthill said.
For years, astrophysicists have been targeting star systems that are halfway between an infant and mature stars – and which may host a family of fully formed planets. The planets within the disc sweep up material that would have otherwise fallen onto the star.
Such a gap exists in LkCa 15’s disk, and one giant protoplanet candidate, known as LkCa 15b, was detected in the system in 2012, at a distance of about 16 astronomical units (AU) from the star.
As you might imagine, the new discovery is a boon to researchers studying how tiny particles of dust accumulate into massive worlds.
Sallum says researchers are just now being able to image objects that are close to and much fainter than a nearby star.
Those instruments include the Large Binocular Telescope, or LBT, the world’s largest telescope, located on Arizona’s Mount Graham, and the UA’s Magellan Telescope and its adaptive optics system, or MagAO, located in Chile.
“The way any planetary system is assembled is a very hot topic in astronomy”, Professor Tuthill said.
“We’re trying to see very faint planets buried in the glare of the star”. “To a big telescope, it’s a fairly dramatic thing; you see a disgusting looking image”. But by using the LBT adaptive optics system and a novel imaging technique, he and Sallum succeeded in getting the crispest infrared images yet of LkCa15.
“That single dark shade of red light is emitted by both the planet and the star as they undergo the same growing process”, said Follette.
Dr Follette explained that when cosmic objects are forming, they get extremely hot, and because they are forming from hydrogen, those objects all glow a deep red (as seen in the image), which astronomers refer to as H-alpha, a particular wavelength of light. This is emitted by stars or even planets when the electron in a hydrogen atom downgrades its energy level in a specific way, something that can happen when dust and gas coalesce into a new planet.
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We see the star surrounded by a disk of material, we see a gap in the disk where the material’s missing, we see the planets that are in the gap, and we see material falling onto the planets.
