Newly-formed gas planets may be surprisingly flat, study finds
New research provides fresh insight into the early stages of planetary formation. A team of astrophysicists has conducted computer simulations suggesting that nascent gas giant planets born within protostellar disks could exhibit significantly flattened geometries. This finding, published in Astronomy and Astrophysics Letters, may reshape our understanding of planetary origins.
A cosmic needle in a haystack
While spotting exoplanets (planets outside our solar system) is becoming more common, finding still-forming protoplanets embedded in their birth disks is like finding that proverbial needle. Only three of these cosmic infants have been discovered so far.
To ‘see’ them requires extremely powerful telescopes and a cosmic lucky break – planets only form over a few million years, a mere tick of the clock on the scales of the universe.
To tackle this, a research team took to supercomputers. They designed simulations capable of peering back in time and determining how infant gas planets behaved under different conditions inside their protostellar disks.
What did they find? Young gas planets within these swirling disks tend to be shaped like oblate spheroids – imagine M&Ms or Smarties in space. In contrast to being perfectly spherical, the intense forces within protostellar disks seem to compress these gas giants from the top and bottom.
Even seasoned planets in our solar system, like Saturn or Jupiter, possess a small amount of “flattening” ” but protoplanets take this to the extreme, averaging closer to a 90% flattening. With time, of course, they grow less squished. This newly discovered characteristic is crucial when analyzing data from our ever-more-powerful telescopes as we search for other worlds in the making.
Competing planet formation theories
The leading model for planet formation, “core accretion,” proposes a gradual, bottom-up process. Within this theory, microscopic dust grains collide and accrete, slowly building up mass. Once a sizable core is established, its gravitational pull can attract and retain vast amounts of gas, generating a gas giant.
An alternative theory, “disk instability,” suggests that gravitationally unstable protostellar disks might fragment directly into planet-sized bodies – a fast-acting, top-down mechanism. This model may better explain the existence of extremely distant gas giants.
The results of this study lend support to the disk instability model by implying that some planets could exhibit significant flattening if formed directly through disk fragmentation.
Not a flat Earth, a flat protoplanet
Earth doesn’t get this extreme. Disk instability cannot form rocky planets such as Earth and Mars. These planets are believed to form gradually by accumulating dust particles, pebbles, rocks, and kilometer-sized objects, and eventually becoming full planets. Due to their high density, they do not get significantly flattened even when they are newly formed. Therefore, there is no possibility that Earth underwent such a high degree of flattening when it was young. Our world was never a cosmic pancake!
Source: Interesting Engineering
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Newly-formed gas planets may be surprisingly flat, study finds