As explained in a paper in Nature today, a team of researchers led by University of Arizona astronomers has become the first to directly image the dust clouds around a baby planet.
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The distant star and the disk of dust and gas that surround it, dubbed LkCa 15, are only about 2 million years old, the team estimates, and each of the protoplanets is less than 10 times the mass of Jupiter. While scientists previously had discovered other immature star systems like LkCa 15, where infantile planets are hypothesized to be growing, Sallum and Follette are the first to directly observe such a planet. “Those would be the planet candidates”, astronomy graduate student Stephanie Sallum, with the University of Arizona, told Discovery News. Zhaohuan Zhu, Princeton University astrophysicist, said that the new study will help scientists modify their previous theories on planet formation. The researchers’ hypothesis – now supported by their images – is that planets form inside the disk, accreting together from the debris and dust.
The star has a transition disk around it, which the university press release describes as “a cosmic whirling dervish, a birthplace for planets”, kind of like what you see in the cover picture for this article.
When planets and stars form, they get extremely hot, and because they form from hydrogen, these objects all glow a dark red which astronomers call the H-alpha, a particular wavelength of light.
While grown-up planets (like the eight in our solar system) are large enough to detect because they can dim the light of their stars as they pass in front, these li’l babies are still too small for that. “This is the first time that we’ve been able to connect a forming planet to a gap in a protoplanetary disk”.
The images have been made possible specifically because the Large Binocular Telescope was purpose-built using a novel imaging technique to overcome these atmospheric distortions, and that the MagAO instrument was able to capture the spectral fingerprint emitted at a specific wavelength of light that LkCa 15 and its planets emit as they grow. The star system, called LkCa 15, could potentially host multiple worlds still in the process of forming. From past observations, the team went on to reconstruct the movement of the new planets and found that their orbits looked circular.
A color so distinct, Close says, that it’s proof positive a planet is forming – something never seen before now. To do so, they used the Large Binocular Telescope in Arizona, combined with a filter that would only let H-alpha photons reach their telescope.
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“We can go and look at this and do more detailed studies now, to try to understand how planets are built”. The planets are likely to be gas giants that orbit between 12 and 24 times further from their star than Earth is from the Sunday.
