Preston, England

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Newly forming exoplanets might be oblate instead of spherical, a new study suggests. 

According to a team of researchers from the University of Central Lancashire (UCLan), young planets turned out to be oblate spheroids, similar to Smarties which in the UK and Europe are oblate spheroid-shaped disks of chocolate covered with colourful hard candy shells. In India, there's a similar candy named "Gems."

The research team used computer simulations to model the shapes of planets in dense gas disks around young stars. They compared these models to observations and found that young planets took some unexpected shapes.

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"We have been studying planet formation for a long time, but never before had we thought to check the shape of the planets as they form in the simulations. We had always assumed that they were spherical," said team member Dimitris Stamatellos, an astrophysicist at UCLan.

Astronomers have discovered over 5,000 exoplanets to date. However, they're still studying the sequence of events leading to their formation and early evolution.

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Initially, the UCLan team observed the gas giants and focused on the shapes of these planets. Some of these were more massive than our solar system. 

According to the standard planet formation theory, the growth happens gradually as dust particles stick together to form progressively larger and larger objects over long periods. This favoured model of planet formation is called "core accretion."

However, planets can arise in shorter timescales when larger rotating protoplanetary disks around young stars split into pieces. This "disk instability" method appears to give more credibility to the less favoured theory. 

"This [disk instability] theory is appealing due to the fact that large planets can form very quickly at large distances from their host star, explaining some exoplanet observations," said UCLan's Adam Fenton. 

Why Do Exoplanets Take The Shape Of Oblate Spheroids?

According to the team's model, newly forming planets are oblate spheroid-shaped because when any material falls onto them, it goes primarily to their poles. 

The research team concluded that the impression of young exoplanets from Earth might differ depending on how these planets are angled. 

An exoplanet might appear spherical if Earth is directed "face on." However, when seen "on edge," a young exoplanet would appear oblate.

Observing young planets, usually surrounded by gas and dust clouds, has become feasible only recently due to advanced telescopes like the Atacama Large Millimeter Array (ALMA) and the Very Large Telescope (VLT). These telescopes could provide evidence to support the Smarties theory.

(With inputs from agencies)