Astronomers image the birth of a planet, verifies formation theory
We already have a pretty good idea of how planets come into existence, but the first one astronomers ever imaged in the midst of formation is LkCa 15 b. The Jupiter-like protoplanet (that's the term used to describe a baby exoplanet), which orbits a young star 450 light-years away, was first caught on cam by Drs. Michael Ireland and Adam Kraus. At the time, however, the scientists weren't sure if they were truly seeing a new planet being born. Now another group of researchers has taken a photo of the LkCa 15 b, and they strongly believe that they "successfully and unambiguously detected a forming planet." Plus, they've verified a formation theory stating that protoplanets glow in the light of incredibly hot (17,500 Fahrenheit) hydrogen gas. The group's paper, which has been published in Nature, combines data from separate studies conducted by two lead authors: University of Arizona graduate student Stephanie Sallum and her former schoolmate Kate Follette, who's now doing postdoctoral research at Stanford University.
The biggest challenge in spotting exoplanets is that the brightness of their stars wash them out too much. As Sallum noted, the difference in brightness between them is "comparable to the difference between a firefly and a lighthouse." Luckily, we have powerful ground-based telescopes now: in this group's case, they used the Large Binocular Telescope in Arizona and the Magellan telescope, which the lead authors' alma matter helped build, in Chile. See, one of the gases that a protoplanet absorbs from the disk is hydrogen, and while the process is ongoing, it emits a wavelength of visible light called "hydrogen alpha." Since the Magellan telescope is capable of seeing H-alpha's shade of red, the astronomers pointed it to the part of the sky where the LkCa 15 b is located.
The image below and the ones in the video were processed by combining infrared photos taken by the Large Binocular with the H-alpha pictures captured by the Magellan telescope. The team also had to remove the host star's overwhelming light and the disturbance brought about by the Earth's atmosphere, but it's clear that they successfully took a photo of planet formation. Sallum, Follette and the rest of the group plan to continue observing the protoplanet in hopes that it can help us better understand the formation of solar systems. Besides, their data suggests that two other baby planets are lurking nearby, and we'll bet they'd love to see those, as well. In addition, if the LkCa 15 b is indeed responsible for the gap observed in the solar system's gas-and-dust donut, then disk gaps could be used as an indicator that a planet is being born.
[Image credit: NASA/JPL-Caltech]
