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Scientists spot a planet as it's being born

Image from the SPHERE instrument on ESO's Very Large Telescope showing a planet forming around the dwarf star PDS 70.
A planet's formation is visible as a bright point to the right of the center of the image, which is blacked out to block the light of the central star PDS 70. Image: ESO/A. Müller et al.

Scientists for the first time spotted a new planet being born while nestled within the dusty disk surrounding a young dwarf star. The findings are detailed in two studies describing an exoplanet in its early state of formation and include the first-known clear image of a young planet forming.

Why it matters: If confirmed through subsequent research, the discovery could teach researchers about how other planets, including ones in our solar system, formed.

The big picture: Circumstellar disks surrounding young stars are considered to be prime candidates for planetary formation but until now, scientists had only detected a few planetary candidates located within these areas.

"The case of PDS 70b gives us the opportunity to observe a planet in its youngest stages of life, and to learn how planets form and evolve on a direct example."
— Miriam Keppler and André Müller, two lead authors of the new studies

What they did: Scientists from the Max Planck Institute for Astronomy in Heidelberg and researchers working with the SPHERE instrument on the Very Large Telescope in Chile observed the nascent planet orbiting the 5-million-year-old star PDS 70 during a six-year period from 2012 to 2018.

  • They used near-infrared images from the VLT and other instruments to study a previously-identified gap within the circumstellar disk, a swirling cloud of gas and dust left over from a star's formation that is thought to be the birthplace of most planets.
  • Such gaps are thought to develop when young planets begin accumulating dust and other material from the disk.
  • Within the gap, the researchers also detected a point source of heat and light, which they designated as PDS 70b.
  • They confirmed the detection of the planet using multiple instruments, each able to see different wavelengths of light, and at varying resolutions.

The details: The findings suggested that the object orbiting PDS 70, within the disk, is a small, extremely young planet. It is likely a gas giant, according to the researchers, with a mass equal to several times that of Jupiter, but an area far smaller than that planet.

According to the European Space Agency, the planet PDS 70b has a surface temperature of around 1,000 degrees Celsius, or 1,832 degrees Fahrenheit, which would be hotter than any planet in our Solar System.

In addition to the study announcing the discovery, published in Astronomy and Astrophysics, researchers examined PDS 70b in more detail, resulting in the first-known clear image of a young planet forming within a circumstellar disk. The second study, published in the same journal, also concluded that the planet likely has a cloudy atmosphere.

What's next: Scientists will continue watching PDS 70b as the planet evolves from the circumstellar disk. Eventually, the planet may emerge from this region to orbit PDS 70 on its own, and the disk will diminish.

Assuming the new research is correct, the observations could go a long way to confirming particular ideas about how planets form.

"Several thousands of planets around other stars have already been discovered. However, how planets really form, and evolve with time is still a matter of debate."
— Miriam Keppler and André Müller, coauthors of the new studies

"This is an exciting discovery as I believe it’s the first unambiguous observation of a planet actually forming within a young disc," said Dimitris Stamatellos, a research fellow in astrophysics at the University of Lancashire, who was not involved in either of the new studies.

"This planet will therefore serve in the future as a test bench for lots of the ideas about planet formation that scientists have been thinking of during the last decade."
— Miriam Keppler and André Müller

The observations are already causing Stamatellos to rethink certain hypotheses planetary formation. He tells Axios it opens up the door for alternative theories like giant planets forming fast due to fragmentation of the disk rather than a standard theory in which they form by coagulation of dust particles.

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