For the first time, astronomers have succeeded in photographing the giant blob that became its forerunner giant gas planet through gravitational instability.
Image of V960 Mon Star with nearby blob with VLT mounted SPHERE. The blue color in the image is the result of the ALMA Radio Telescope observation. Credit: ESO/ALMA (ESO/NAOJ/NRAO)/Weber et al.
A blob near the V960 Star Mon
V960 star system Mon. Bintang which is 5,000 light years from Earth in the constellation Monoceros, is the star FU Orionis, a pre-Main Sequence star that exhibits extreme changes in brightness in its spectrum type.
The same is of course the case with the V960 Mon. This star has experienced more than 20 brightness changes since 2014! In short, the V960 Mon is always in turbulent periods that trigger changes in brightness.
In the observations made with the instrument Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) installed on Very Large Telescope ESO, astronomers managed to capture details of the area around the star V960 Mon. As with newly formed stars, astronomers also found remnants of star-forming material still around V960 Mon.
Not only that.
The SPHERE instrument was able to look in detail at the area around the star and found that material around the young star V960 Mon was clumping together in a complex series of spiral arms spanning several thousand astronomical units. The scope of this spiral arm is even larger than the entire Solar System!
This accumulating material looks like clumps that have the potential to become the forerunners of giant planets. Interesting? Of course! Moreover, the process of formation of gas giant planets is still not fully understood.
Still full of mystery!
The Formation of a Gas Giant Planet
When stars form, the remaining matter in the form of gas and dust forms a disk around the star. Inside the disc of gas and dust we know by name protoplanetary disk here it is planet formed. If the ideal model we know is the Solar System, then the planets that form near stars are rocky planets or terrestrial planets. Meanwhile, giant gas planets are formed far from stars.
However, observations of other stars actually show the presence of giant planets, in this case Jupiter-like planets near the star.
The question is, how did gas giant planets form?
There are two theories for the formation of giant planets: the core accretion theory and the gravitational instability theory.
According to the theory of nuclear accretion, the formation of gas giant planets begins with the formation of a planetary core from continuous growth of dust. The dust accumulated to form the planet’s core until it was several Earth masses in size. After that, the rock core begins to capture gas in the surrounding protoplanetary disk until the gas runs out.
Meanwhile, according to the theory of gravitational instability, gas planets will instantly form from within the protoplanetary disk when a large amount of matter around the star contracts and collapses.
Both of these models have their strengths and weaknesses. Until now, the core accretion theory is still the favorite model for the formation of giant planets. However, observations of the V960 Mon provide a different insight. This could be the first detection of giant planet formation through gravitational instability.
Gravity Instability
Comparison of the V960 Mon image captured by SPHERE on the VLT (left) and by the ALMA Radio Telescope (right). Credit: ESO/ALMA (ESO/NAOJ/NRAO)/Weber et al.
To analyze what happened to the V960 Mon system, astronomers used observational data from the ALMA radio telescope. So astronomers used VLT observational data to study the surface of the clumps of dusty material around the star V960 Mon. Meanwhile, ALMA data is actually used to understand the structure of the blob.
From ALMA data, astronomers found that the spiral arms observed near the star were undergoing fragmentation which resulted in the formation of clumps with masses equivalent to the mass of planets.
Such spiral structures have been observed in several systems protobintang. The spiral arms formed in this event also come in a variety of sizes, numbers, and sources. Some of the possibilities for the formation of these spiral arms come from the presence of a massive object as a partner, gravitational instability, partner double starflying across the stars alias passing stars, or a combination of these processes.
The complex environment surrounding V960 Mon poses a challenge in determining the cause of this spiral arm-shaped light-distributing structure. However, the simulation results also show that a disk that is experiencing gravitational instability will not be able to maintain the spiral arm structure beyond a radius of 100 AU for a long time. This is because disks of matter tend to split or split at larger radii. Only gravitational instability could explain the disintegration of the spiral arms into lumps.
The fate of the lump
During gravitational instability, the disk of matter around the star will produce large-scale spiral arms as seen in the scattered light around V960 Mon. This spiral structure would generate shock waves throughout the disk, heating material on the disk, and regulating or potentially preventing gravitational collapse. The end result of gravitational collapse depends on the efficiency of the material within the disk to radiate thermal energy which is related to the cooling time scale.
The presence of these lumps was the first evidence of the spiral arms breaking apart. In addition, this discovery also shows that gravitational instability in the formation of clumps of forerunner planet mass in a protoplanetary disk can indeed occur.
In the long term, the blobs found on V960 Mon could disintegrate after being formed due to gravitational interactions with other blobs. Alternatively, gravitational interactions could produce an accretion explosion that triggers the formation of new clumps that are ejected into interstellar space and become wandering planets.
However, the fate of these blobs depends on their rate of migration. If it is slow, then this blob has the potential to form planets whereas if the rate of migration is fast, this blob will actually be destroyed.
Either way, these observations are evidence of the possibility of planet formation from gravitational instability.
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2023-07-25 13:00:00
#Gravitational #Instability #Birth #Planets
