UMD Astronomer Leads Study That Finds Water in Asteroid Belt Comet

Using infrared technology on NASA’s James Webb Space Telescope, a University of Maryland-led team of astronomers for the first time has confirmed the presence of gas—specifically water vapor—around a comet in the solar system’s main asteroid belt.

Their study, published this week in the journal Nature, centered on Comet 238P/Read, which periodically displays a halo (technically known as “coma”) and the familiar comet tail and is a member of a rare subclass of comets that exist in the asteroid belt between Mars and Jupiter.

“In the past, we’ve seen objects in the main belt with all the characteristics of comets, but only with this precise spectral data from Webb can we say, yes, it’s definitely water ice that is creating that effect,” said the study’s lead author, Michael Kelley, a research scientist in the UMD Department of Astronomy.

The findings also present a new puzzle: Unlike other comets, Comet Read had no detectable carbon dioxide. Typically, carbon dioxide makes up about 10% of the volatile material in a comet that can be easily vaporized by the sun’s heat.

Kelley said it is possible that Comet Read had carbon dioxide when it formed but lost it because of warm temperatures. Alternatively, he said, Comet Read may have formed in a particularly warm pocket of the solar system where no carbon dioxide was available.

Beyond shedding light on main belt comets, these findings bring researchers a step closer to understanding the origins of Earth’s abundant water, the researchers said. Other co-authors hail from the Association of Universities for Research in Astronomy, the Institute of Astronomy and Astrophysics, Academia Sinica in Taiwan, Auburn University and NASA Goddard Space Flight Center.

This article was adapted from a news release provided by the Space Telescope Science Institute.