ESOcast 164 Light: ALMA Discovers Trio of Infant Planets (4K UHD)

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Both teams concluded there was sufficient evidence to suggest that three infant planets were being born around HD 163296. Their new method looked at unusual patterns of gas flowing in the disk to find the telltale signs of planets.

Rather than focusing on the dust within the disc, which was clearly imaged in earlier ALMA observations, the astronomers instead studied carbon monoxide (CO) gas spread throughout the disc. Molecules of CO emit a very distinctive millimetre-wavelength light that ALMA can observe in great detail. These disks are filled with gas and dust and ringed gaps inside them can provide evidence for the presence of planets.

Using a new planet-hunting technique, astronomers have discovered a trio of young planets orbiting around a newborn star.

All three planets orbit a star known as HD 162396, that is situated about 330 million light-years away from earth in the constellation of Sagittarius (The Archer).

"When a planet forms in a protoplanetary disk it can carve a gap and produce wakes in the disk".

"This entirely new approach could uncover some of the youngest planets in our galaxy, all thanks to the high-resolution images from ALMA (Atacama Large Millimeter/submillimeter Array)", said Richard Teague, an astronomer at the University of MI and principal author on the other paper.

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"Measuring the flow of gas within a protoplanetary disc gives us much more certainty that planets are present around a young star", Christophe Pinte, lead author on one of the two papers, said in a statement.

That's why the traditional methods that are used to find exoplanets, like looking for dips in starlight as planets pass in front of their star, don't work for planets that are still developing.

Dr. Teague and co-authors identified two Jupiter-mass planets located approximately 83 AU (astronomical units) and 137 AU from the star.

Young stars are surrounded by rotating discs of gas and dust from which planets are formed.

Specifically, the researchers looked for subtle changes in the levels of carbon monoxide (CO) in high-res images captured by ALMA.

These astronomers are hopeful their technique can be applied to other young stars throughout the galaxy, in order to study some of our galaxy's youngest planets. According to him, "this method promises to open new perspective direction in the theory of the formation of planetary systems".

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The new technique is less likely to generate false positives, the astronomers say, and will permit more accurate estimates of the masses of protoplanetary discs.

Due to extensive observations over the years, astronomers are beginning to learn how planets form around a star.

Pinte and his team more directly measured the gas's actual velocity, which is a better for studying the outer portion of the disk and can more accurately pinpoint the location of a potential planet. Orbiting at distances of 83 and 137 times that between the sun and Earth, the planets' host star is actually significantly brighter than our own parent star.

The researchers detailed their discoveries in two papers published Wednesday in the journal Astrophysical Journal Letters.

Kinematic evidence for an embedded protoplanet in a circumstellar disc, by C. Pinte et al., 2018, to appear in Astrophysical Journal Letters.

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