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Astronomers using the Atacama Large Millimeter / Subillimeter Array (ALMA)Atacama Large Millimeter / Subillimeter Array (ALMA)Founded by the US National Science Foundation and its international partners (NRAO / ESO / NAOJ), ALMA is one of the most complex and powerful astronomical observatories on Earth or in space. The telescope is a network of 66 high-precision satellite dishes located in northern Chile. See more here have made the earliest observations of a circumplanetary disk, the belt of dust and gas that astronomers strongly theorize, control the formation of planets and give birth to a complete system of moons, like those found around Jupiter.
This unpublished feature was discovered around one of the planets of PDS 70, a young star located about 370 light-years from Earth. Recently, astronomers have confirmed the presence of two massive planets, Jupiter type. This previous discovery was made with the very large telescope (VLT) of the European Southern Observatory, which detected the warm glow naturally emitted by hydrogen gas growing on the planets.
The new ALMA observations instead reflect the weak radio waves emitted by the tiny dust particles (about a tenth of a millimeter) around the star.
The ALMA data, combined with the previous VLT optical and infrared observations, provide compelling evidence that a dusty disk capable of forming multiple moons surrounds the planet's best-known planet.
"For the first time, we can conclusively see the telltale signs of a circumplanetary disk, which supports many of the current theories of planet formation," said Andrea Isella, an astronomer at Rice University in Houston. Texas, and lead author of the site. an article published in the Astrophysical Journal, Letters.
"By comparing our observations to high-resolution infrared and optical images, we can clearly see that an otherwise enigmatic concentration of tiny dust particles is actually a dust disk that surrounds the planet, the first characteristic of this type ever observed. conclusively, "he said. According to the researchers, this is also the first time that a planet is clearly visible in these three distinct light bands.
Unlike the icy rings of Saturn, which have probably formed recently during the crushing of comets and rocky bodies in the history of our solar system, a circumplanetary disk is the persistent trace of the process of planet formation.
ALMA data also revealed two distinct differences between the two recently discovered planets. The closest of the two, the PDS 70b, which is about the same distance from its star as Uranus in the sun, has behind it a dust mass that looks like a tail. "What it is and what it means for this planetary system is not yet known," Isella said. "The only conclusive thing we can say is that the planet is far enough apart to be an independent element."
The second planet, PDS 70c, is exactly in the same location as a visible dust node in the ALMA data. Astronomers can convincingly say that a fully formed planet is already in orbit and nearby gases continue to be syphonized on the surface of the planet, ending its growth spurt in adolescence.
This outer planet is located about 5.3 billion kilometers from the host star, about the same distance as Neptune from our Sun. Astronomers estimate that this planet represents about 1 to 10 times the mass of Jupiter. "If the planet is in the widest part of this estimate, it is quite possible that planet-sized moons form around it," Isella said.
ALMA data also adds an important element to these observations.
Optical studies of planetary systems are notoriously difficult. Since the star is so much brighter than the planets, it is difficult to filter the glare, much like trying to spot a firefly next to a projector. However, ALMA observations do not have this limit because stars emit relatively little light at millimetric and submillimetric wavelengths.
"This means we can return to this system at different times and better map the orbit of the planets and the concentration of dust in the system," Isella concluded. "This will give us unique insights into the orbital properties of solar systems in their very early stages of development."
The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under a cooperative agreement by Associated Universities, Inc.
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Contact: Charles E. Blue: Public Information Officer
[email protected]; 434-296-0314
Reference: "Detection of submillimetric continuum emissions associated with candidate protoplanets", A. Isella et al., The Astrophysical Journal Letters: apjl.aas.org; Preprint: https://arxiv.org/abs/1906.06308
The Atacama Large Millimeter / Submillimeter Array International Astronomy Research Center (ALMA) is a partnership of the European Organization for Astronomy Research in the Southern Hemisphere (ESO), the National Science Foundation (NSF) and the National Institutes of Science Natural Resources (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States by NSF in cooperation with the National Research Council of Canada (NRC) and the Ministry of Science and Technology (MOST) and NINS in cooperation with Academia Sinica ( AS) in Taiwan. and the Korean Institute of Astronomy and Space Science (KASI).
The construction and operations of ALMA are led by ESO on behalf of its member states; by the National Radio Astronomy Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and by the National Astronomical Observatory of Japan (NAOJ) on behalf of East Asia. The ALMA Joint Observatory (JAO) provides unified management and management of the construction, commissioning and operation of ALMA.
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