Hot Jupiter

An artist’s impression of the “hot Jupiter” exoplanet. Credit: NASA/JPL-Caltech

A new planet begins its life in a swirling circle of gas and dust, called a cradle. Protostellar disk. My colleagues and I have used computer simulations to show that the nascent gas planets in these disks are likely to have surprisingly flat shapes. This discovery, Published in Astronomy and Astrophysics LettersIt could add to our picture of how planets form.

Observing protoplanets that have just formed and are still inside their protostellar disk. Only three such young protoplanets have been observed so far, two of which are in the same system, PDS 70.

We need to find systems that are young, and close enough for our telescopes to detect the faint light from the planet itself and distinguish it from the disc. The entire process of planet formation takes only a few million years, which is nothing but the blink of an eye in astrophysical scales. That means we need luck to catch them in the making.

Our research group performed. To determine the properties of gaseous protoplanets at different thermal conditions in planetary cradles.

The simulations have sufficient resolution to be able to follow the evolution of a. in the disc from the earliest stage, when it is merely condensation within the disc. Such simulations are computationally demanding and run. DIRAC, UK Astrophysics Supercomputing Facility.

Typically, multiple planets form within a disk. Research has shown that the shape of protoplanets is rather oblate spheroids like Smarties or M&M’s. They grow by drawing in gas primarily through their poles rather than their equator.

Technically, our planet There are also coarse spheres but their flattening is small. Saturn is flat 10%, Jupiter 6%, while Earth is only 0.3%..

In comparison, the typical flatness of protoplanets is 90%. Such flattening will affect the observed properties of the protoplanets, and must be taken into account when interpreting the observations.

How do planets begin?

The most popular theory for planet formation This is the “fundamental enhancement”.. According to this model, Smaller than sand collide with each other, group together and gradually grow into larger and larger bodies. This effectively happens with the dust under your bed when it is not cleaned.

Once a dust particle forms large enough, it pulls gas from the disk to form a gas giant. It will take a few million years to get from this bottom to the top.

The opposite, the top-down approach, is Disc Instability Theory. In this model, protostellar disks that participate are gravitationally unstable. In other words, they are too heavy to sustain and therefore break up into fragments, which turn into planets.

The core accretion theory has been around for a long time and can explain many aspects of the formation of our solar system. However, disc instability may better explain some exoplanetary systems discovered in recent decades, such as those where a gas giant planet orbits far from its host star.

The appeal of this theory is that planet formation occurs very rapidly over a few thousand years, which is consistent with observations that suggest that planets exist in very small disks.

Our study focused on gas giant planets formed by the disc instability model. They are flat because they form from the compression of an already flat structure, the protostellar disk, but also because of how they rotate.

There is no flat earth.

Although these protoplanets are very flat overall, their cores, which would eventually evolve into the gas giant planets as we know them, are less flat—only about 20 percent. That’s just twice the flattening of Saturn. They are expected to become more spherical over time.

Rocky planets, such as Earth and Mars, cannot form from disc instability. They are thought to form by the gradual aggregation of soil particles into pebbles, rocks, kilometer-sized objects, and eventually planets. They are so dense that they flatten significantly when newly born. There is no possibility that the Earth was so flat when it was young.

But our study supports a role for disc instability in the case of some worlds in some planetary systems.

We are now moving from the era of exoplanet discoveries to the era of exoplanet characterization. Many new observatories are about to become operational. These will help discover more protoplanets embedded in their disks. Predictions from computer models are also becoming more sophisticated.

Comparison between them And observations are bringing us closer to understanding the origins of our solar system.

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Reference: Newborn gas planets may be surprisingly flat, new study (2024, February 17) Retrieved February 17, 2024 from https://phys.org/news/2024-02-newborn-gas-planets-flat.html done

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