A professor receives a grant from NASA for his research on Pluto

By Jessica Brinegar NMSU Press Team

In 2019, the New Horizons spacecraft flew past a snowman-shaped object in the Kuiper Belt, a giant ring on the outskirts of our solar system made up of rocky, icy bodies orbiting the sun. Later named Arrokoth, the two-lobed body is an example of what astronomers call planetesimal, considered the building blocks of planets. Arrokoth has provided astronomers with insight, and many more questions, about how planets form.

New Mexico State University assistant professor of astronomy Wladimir Lyra has been awarded a three-year, $365,000 NASA-Emerging Worlds grant to further our understanding of how these planetesimals form in circumstellar disks. .

“The Kuiper Belt is a wealth of information about planetesimal formation,” Lyra said.

The belt of circumstellar material is home to Pluto, the dwarf planet discovered by the late NMSU astronomer Clyde Tombaugh.

The research will build on preliminary work done by graduate student and research assistant Manuel Cañas, who will continue the work with Lyra. Cañas came to NMSU from South Carolina but is originally from Colombia. He was drawn to NMSU because of the astronomy department’s research reputation.

“It’s a very good school for astronomy research,” Cañas said. “Apart from research and school, I love computer programming, which is another reason I love this project – it’s very computationally intensive.”

Using computer simulations, Lyra builds models that predict planet formation mechanisms which are then compared to observational data collected by other researchers. These models allow him to create and verify theories on the formation of planets.

“For a long time, the idea was that you formed planets by first forming asteroid-mass bodies, which we call planetesimals, and then colliding with each other,” Lyra said.

When asked how these planetesimals begin to form, Lyra provided a fun visualization. “You know when you don’t clean your room enough and dust bunnies form? Now imagine that you don’t clean your room for 10 million years.

The result is that these cosmic dust bunnies grow to the size of pebbles. Subsequently, by interacting with the gas they rapidly pass through, these pebbles naturally develop an aerodynamic process to reduce the drag (such as the V formation that birds adopt) felt during orbit. This process, opaquely called “flow instability”, strongly concentrates the pebbles to form planetesimals.

As these planetesimals continue to grow, an interesting trend in their densities is beginning to emerge. “Smaller objects, such as Arrokoth, have very low densities, like the densities of ice, and larger mass objects like Pluto have much higher densities,” Lyra said.

“Our research has implications for the formation of Pluto. It’s only fitting that we do that here at NMSU, the academic home of Clyde Tombaugh,” Lyra said. The New Horizons spacecraft that flew past Pluto is carrying some of Clyde’s ashes, isn’t it mind-blowing?

“I haven’t had a chance to meet Clyde. If I had, I like to think I’d tell him I’m working on explaining how Pluto got there for him to find out 4.5 billion d years later, and that I feel privileged and honored to carry on his legacy.

Tombaugh (1906-97) discovered Pluto at Lowell Observatory in Flagstaff, Arizona on February 18, 1930, two weeks after Tombaugh’s 24th^e birthday. Tombaugh worked at White Sands Missile Range in the early 1950s and taught astronomy at New Mexico State University from 1955 until 1973 when he retired. He was inducted into the International Space Hall of Fame in 1980. Pluto was reclassified from a planet to a dwarf planet in 2006.