Gravitational Instability's Key Role in Planet Formation Revealed as Scientists Studies Young Star

Researchers used the Atacama Large Millimeter/submillimeter Array to study Elias 2-27, a young star in the Ophiuchus Molecular Cloud, confirms the vital role gravitational instabilities play in the formation of planets. Additionally, researchers have been able, for the first time, to directly measure the mass of protoplanetary disks unlocking the secrets behind planet formation.

Protoplanetary Disks Explained

According to the Encyclopedia of Astrobiology, protoplanetary disks are comprised of 99% mass of gas and only 1% mass of dust constantly orbiting newly formed stars. For many years scientists have theorized that protoplanetary disks are the birthplace of planets.

These gaseous disks are coom by-products of star formation and range in mass from 0.001 to 0.3 Solar masses and size from several tests to more than 1,000 Astronomical Units. Inside protoplanetary disks, matter moves slowly inwards, dust grows into pebbles, and is the first step towards forming kilometer-sized planetesimals.

Typically in 2-3 million years, protoplanetary disks disperse via coalescence of matter into planets and photoevaporation due to stellar radiation.

Despite this, the exact process of forming planets has remained a mystery to scientists for generations.

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Gravitational Instability's Role in Planet Formation

The research led by Teresa Paneque-Carreño focused on unlocking the secrets behind planet formation in a study published in The Astrophysical Journal, entitled Spiral Arms and a Massive Dust Disk with non-Keplerian Kinematics: Possible Evidence for Gravitational Instability in the Disk of Elias 2-27.

During the team's observation, they confirmed that the Elias 2-27 star system, a juvenile star less than 400 light-years from Earth in the Ophiuchus constellation, exhibited evidence of gravitational instabilities occurring when planet-forming disks carry enormous fractions of the system's stellar mass.

Paneque-Carreño says that the exact 'hows' of planets forming is the main question researchers hope to answer. However, there are vital mechanisms that the team believes can hasten the process of planet formation. She adds that the team discovered direct evidence of gravitational instabilities in the juvenile star that excites researchers because it is the first time researchers can demonstrate kinematic and multi-wavelength proof and gravitationally unstable systems. While Elias 2-27 is the only, so far, system that ticks all the boxes as reported by Science Daily.

Elias 2-27's distinct characteristics have made it a popular topic among ALMA researchers for over half a decade. In 2016, researchers using ALMA discovered a pinwheel of dust surrounding and swirling around a young star. The spiral was believed to be a result of density waves that are commonly produced and recognizable in spiral galaxies such as the Milky Way, but until that point has never been seen in individual stars.

Paneque-Carreño explains that although the recent research proves gravitational instabilities' key role in planet formation in the spiral structures in the dust continuum around the star, there exists an inner gap, a missing material in the protoplanetary disks, that researchers are unable to explain.

Although researchers have been able to give proof and answer the key questions regarding the role of gravitational instability and disk mass in the formation of the planet, the work is far from over.