UT astronomer to trace back planetary formation

Samah Khan

The ingredients for life originated right outside the solar system, according to astronomy professor Neal J. Evans II.

On Saturday, Evans will deliver the 24th Annual Great Lecture in Astronomy at UT’s Avaya Auditorium. The lecture, entitled “Astrochemistry: A Song of Ice and Dust,” will reveal how solar systems are created from condensed disks of icy dust particles.

The makeup of the particles provide clues about how planets such as Earth form or even how life originated on the planet. Evans and his colleagues have identified dust and ice particles with similar compositions to those that made the earth, which could mean that habitable planets are developing elsewhere.

“We’re tracing our genealogy back to the cloud that formed the sun,” Evans said. “We are looking at other stellar regions that are forming now so that we get a picture of what it was like when our solar system formed.”  

Ice particles, called volatiles, are made up of frozen water, carbon, nitrogen or other gases. Asteroids with water volatiles collided with the newly formed Earth, delivering ice and other biological elements to the planet, according to the Departments of Biophysical Sciences and Chemistry at the University of Houston.

Evans’ research focuses on discovering the composition of these icy particles.

“That’s what we’re made of,” Evans said. “We are essentially ice.”

To discover the chemical composition of the ice, Evans uses a technique called astronomical spectroscopy. This method measures wavelengths of light emitted from vibrating ice particles viewed from telescopes. Evans can read the particles’ signature wavelengths to detect their chemical composition.

Yao-Lun Yang, an astronomy graduate student at UT, said that studying sun-like stars is vital to understanding the formation of solar systems. 

Scientists can analyze these stars to learn about the origins of the Earth because they produce disks of ice and dust similar to those found around the sun, according to Yang.

“One of the questions we ask ourselves is ‘how can we have sun-like stars?’” Yang said. “It all goes back to the end product, which is our Earth. Everything is tied together.”

Until now, the scientists have been using images from the Hubble space telescope to study these particles. In October 2018, NASA will launch the James Webb space telescope, which will provide researchers with an even more sensitive instrument to analyze ice and dust particles around stars.

“This will allow us to dig even deeper into the nature of the disks.” Evans said.

He said he was inspired to study the origin of planets while pursuing his Ph.D. in physics at UC Berkeley. His thesis advisor gathered a group of postgraduates to search for molecules in space.

“It was a fascinating thing to do,” he said. “It meant that suddenly there was much more chemical richness in the universe than we originally thought.”

Evans said his research ties together different aspects of stellar and planetary research in an understandable way.

Emma Yu, an astronomy graduate student who works with Evans to model planetary disks, said she is eager to learn more about the science behind the birth of solar systems.

“I’m personally excited about being able to explain how different kinds of planets are formed,” Yu said. “Because we know the beginning — the disks — and the end — the planets — but we don’t know what’s linking them. We want to know how special the Earth is.”