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Unknown tax land of planets found hiding in dust

et al. . The Taurus molecule protection, depicted here by ESA's Herschel Space Observatory, is a star-forming region about 450…

et al. .

The Taurus molecule protection, depicted here by ESA’s Herschel Space Observatory, is a star-forming region about 450 light years away. The picture frame covers approximately 14 of 16 light years and shows the glow of cosmic dust in the interstellar material that permeates the cloud, revealing an intricate pattern of threads dotted with some compact, light nuclei – seeds of future stars. Credit: ESA / Herschel / PACS, SPIRE / Gould Belt Survey Key Program / Palmeirim et al. . 2013

“Super-Earths” and Neptune-sized planets could form around young stars in much greater numbers than researchers thought, suggesting new research by an international team of astronomers.

Observing a selection of young stars in a constellation of the constellation of Taurus, researchers found that many of them would be surrounded by structures that could best be explained as traces created by invisible, young planets in the production. The research, published in the Astrophysical Journal helps researchers better understand how our own solar system came.

Some 4.6 billion years ago our solar system was a moving, swirling swirl of gas and dust around our newborn sun. In the early stages, the so-called protoplanetic disc had no distinguishable characteristics, but soon parts of it began to accumulate in material clumps – future planets. When they picked up new material along their journey around the sun, they grew and began to plow patterns of slots and rings in the disc that they formed. Over time, the dusty disc became the relatively arranged arrangement we know today, consisting of planets, moons, asteroids and occasional comets.

Researchers build this scenario on how our solar system came upon observations of protoplanetary discs around other stars that are young enough to be currently in the process of born planets. Using the Atacama Large Millimeter Array, or ALMA, which consisted of 45 radio antennas in the Chilean Atacama desert, the team conducted a survey of young stars in the Taurus starring region, a large cloud of gas and dust locating a modest 450 light years from Earth. When the researchers formed 32 stars surrounded by protoplanetary discs, they found that 12 of them -40 percent have rings and gaps, structures that, according to the team’s measurements and calculations, can best be explained by the presence of growing planets.

This is fascinating because it is the first time exoplanet statistics suggest that the super-earth and the neptunes are the most common type of planets, coinciding with observations of protoplanetary discs, says paper leader, Feng Long, doctoral student at the Kavli Institute for Astronomy and Astrophysics at Beijing University in Bejing, China.

While some protoplanetic dishes look like uniform, pancake-like objects lack any characteristics or patterns, concentric bright rings separated by gaps have been observed, but earlier surveys have focused on the brightest of these objects because they are easier to find, It was unclear how common dishes with ring and gap structures really are in the universe. This study presents the results of the first objective survey by selecting the target discs independently of their brightness, in other words, the researchers did not know if any of their goals had ring structures when they selected them for the survey.

“Most previous observations had been aimed at detecting the presence of very massive planets, which we know are rare, which had cut out large internal holes or slots in light discs,” said the second author of the paper, Paola Pinilla, a NASA Hubble- fellow at the University of Arizona Steward Observatory. “While massive planets had expired in some of these candles, some had been known about the tougher discs.”

Until recently, protoplanetary dishes were thought to be smooth, like pancake-like objects. The results from this study show that some dishes are more like donuts, but appear even more often as a series of rings. The rings are probably carved by planets that are otherwise invisible to us. Credit: Feng Long

The team, which also includes Nathan Hendler and Ilaria Pascucci at UA’s Lunar and Planetary Laboratory, measured the properties of rings and gaps observed with ALMA and analyzed data to evaluate possible mechanisms that could cause the observed rings and gaps . Although these structures can be cut by planets, previous research has suggested that they can also be created by other effects. In a generally proposed scenario, so-called ice lines cause changes in dust chemistry across the disc in response to the distance to the host star and its magnetic fields create pressure variations across the disc. These effects can create variations in the disc that manifests like rings and gaps.

The researchers conducted analyzes to test these alternate explanations and could not establish any relationship between star features and patterns of gaps and rings that they observed.

We can therefore rule out the widely proposed idea of ​​ice lines that cause the rings and gaps, “said Pinilla. “Our thinking leaves growing planets as the most likely reason for the patterns we observed, although some other processes may also be at work.”

Because it is impossible to discover the individual planets impossible due to the overwhelming brightness of the host star, the team performed calculations to get an idea of ​​what planets can be formed in the Taurus constellation region. According to the results, Neptune-sized gas planets or so-called super-earth planets of up to 20 earthmasses would be the most common. Only two of the discs observed may potentially end behemoth’s rivaling Jupiter, the largest planet in the solar system.

“Since most exoplanet studies can not penetrate the thick dust of the protoplanetary disk, all exoplanets, with an exception, have been discovered in more developed systems where a disc is no longer present,” said Pinilla.

The research group plans to move ALMAs antennas farther apart, which would increase the resolution to about five astronomical units (an AU equals the average distance between the ground and the sun) and to make antennas sensitive to other frequencies sensitive to other types of dust.

“Our Results are an exciting step to understand this key phase of planetary formation “To put it,” and by making these adjustments, we hope to better understand the origins of the rings and gaps. “

Explore further:
Protoplanetary disc material turned out to be too sparse to form planet populations

More information:
Feng Long et al., Gaps and Rings in an ALMA Examination of Disks in Taurus Star-forming Region, Astrophysical Journal (2018). DOI: 10.3847 / 1538-4357 / aae8e1

Journal Reference:
Astrophysical journal

Provided by:
University of Arizona

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