Interstellar Gas Clouds

HL Tauri, a young star located 450 light-years away in the constellation of Taurus, is glowing at the center of an system of concentric protoplanetary rings and is producing planets, one for each gap in the ring. Worcester Polytechnic Institute mathematical physicist Dr. Mayer Humi believes HL Tauri provides an apt study target for theories about protoplanetary rings around stars.

This image shows the protoplanetary disk surrounding the young star HL Tauri. Image credit: ALMA / ESO / NAOJ / NRAO.

HL Tauri awakened interest in Pierre-Simon Laplace’s 1796 conjecture that primitive interstellar gas clouds around new stars condense to form rings and then planets.

The image of HL Tauri taken in October 2014 by the Atacama Large Millimeter/submillimeter Array is the first time planetary rings have been photographed in such crisp detail, an observational confirmation of Laplace’s conjecture.

“We can observe many gas clouds in the Universe that can evolve into a solar system,” Dr. Humi said.

“Recent observational data shows solar systems are abundant in the Universe, and some of them might harbor different types of life.”

Dr. Humi wondered about the creation of solar systems and their evolution in the Universe: how do they form and what trajectory will they follow in the future?

“The basic issue was and is how a primordial cloud of gas can evolve under its own gravitation to create a solar system,” he said.

In the new study, he used the Euler-Poisson equations, which describe the evolution of gas clouds, and reduced them from six to three model equations to apply to axi-symmetric rotating gas clouds.

He considered the fluid in the primordial gas cloud to be an incompressible, stratified fluid flow and derived time dependent solutions to study the evolution of density patterns and oscillations in the cloud.

His work shows that, with the right set of circumstances, rings could form from the cloud of dust and gas.

It lends credence to Laplace’s 1796 hypothesis that our Solar System formed from a similar dust and gas cloud around the Sun.

“I was able to present three analytical solutions that demonstrate rings can form, insight that cannot be obtained from the original system of equations,” Dr. Humi said.

“The real challenge is to show that the rings can evolve further to create the planets.”

The research was published in the Journal of Mathematical Physics.

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Mayer Humi. 2020. On the evolution of a primordial interstellar gas cloud featured. Journal of Mathematical Physics 61, 093504; doi: 10.1063/1.5144917