REPUBLIKA.CO.ID, JAKARTA— The James Webb Space Telescope (JWST) has observed a planet-forming disk emitting cold “steam”. This provides important evidence for the leading theory explaining how planets form.
This excess water vapor is detected by Telescope Space James Webb in two disks of gas and dust surrounding young stars that are only two million to three million years old, which is a very young number in the scope of our universe’s timeline. The disk is located in the star-forming region of Taurus, which is about 430 light years away.
Reported Space, Friday (10/11/2023), astronomers believe that planets are formed through a process that begins with what is called “gravel accretion”. It involves small chunks of silicate relief, ranging in size from centimeters to about a meter, which are coated with ice.
They are thought to begin their lives on the outside of frozen planet-forming disks, usually home to comets, and eventually begin to experience friction with the gas within the disk. This friction may rob the pebble of orbital energy and cause it to migrate to the interior of the disk.
As they gathered in the inner world, the pebbles are thought to have started colliding with each other and sticking together, slowly growing into larger and larger objects until they became protoplanets. From there, the protoplanet’s much stronger gravity allowed them to sweep up the pebbles at a faster rate, accelerating their growth. That’s the long-standing theory of planet formation.
The water vapor detected by JWST’s Mid-Infrared Instrument (MIRI) is evidence of this process because this type of water is thought to come from migrating ice pebbles.
As ice pebbles drift inward, they are believed to cross a boundary called the “snow line.” In our solar system, the snow line is just inside Jupiter’s orbit when the planets formed.
Within this limit, the temperature inside the disk is considered too high to allow water to become ice. The layer of ice on the gravel will evaporate, causing the injection of cold water vapor into the interior of the disc. That’s what MIRI can detect.
“Webb finally uncovered the connection between water vapor in the inner disk and the movement of ice pebbles from the outer disk,” Andrea Banzatti of Texas State University, lead author of a new paper describing the JWST observations, said in a statement.
JWST observed a total of four planet-forming disks. Two disks are quite compact, and two disks are elongated and undergo a lot of inward migration. Water vapor is only found in the two compact disks.
However, there are still unanswered questions. For example, two expanded disks, belonging to systems called CI Tau and IQ Tau, appear like rings in images taken by the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile. How these rings form is still debated, but one theory is that when migrating gravel encounters an area of higher pressure, the flow into it slows.
The deceleration is thought to hold the pebble inside this kind of pressure trap, forcing it to manifest as a ring. However, how these rings affect the formation of planets due to the addition of gravel in them is still unclear. It is also interesting that two compact disks, called GK Tau and HP Tau, show no evidence of a ring-like structure.
Another open question concerns the accretion process. What conditions are necessary for pebbles to stick together when they collide and form larger objects without breaking into pieces?
JWST observations supporting inward migration of gravel suggest an answer to this puzzle, but we just need to find out what the answer is. Hopefully JWST will be the key, this observatory can help strengthen a more modern picture of how planets form.
Colette Salyk of Vassar College in New York, who is one of the authors of the paper explaining the JWST results, said in the statement, that in the past, we had a very static picture of planet formation, almost like isolated zones where planets formed. “Now we have evidence that these zones can interact with each other,” Salyk said.
Salyk also shows that pebble accretion is thought to have occurred 4.5 billion years ago in our solar system, meaning JWST’s observations tell us not only about how exoplanets form, but also how planets Earth we are born.
The Indonesian U-17 World Cup will take place from 10 November to 2 December 2023. Immediately buy and get official tickets to the U-17 World Cup matches in Jakarta, Bandung, Solo and Surabaya
on the page
2023-11-09 21:59:26
#Webb #Telescope #Reveals #Mystery #Earths #Formation #Billions #Years #Republican #Online
