NASA's Spitzer spots giant debris cloud from clashing asteroid-sized bodies

A team of astronomers have reported the first observations of a debris cloud from a collision between two large asteroid-sized bodies. The team used data from NASA's Spitzer Space Telescope to determine the cloud's size post-impact and estimate the size of the objects that collided.

The team led by Kate Su of the University of Arizona started making routine observations of a 10 million-year-old star called HD 166191 in 2015. Between 2015 and 2019, they conducted more than 100 observations of the system using NASA's Spitzer that detected infrared light – or wavelengths slightly longer than what human eyes can see.

"In mid-2018, the space telescope saw the HD 166191 system become significantly brighter, suggesting an increase in debris production. During that time, Spitzer also detected a debris cloud blocking the star. Combining Spitzer's observation of the transit with observations by telescopes on the ground, the team could deduce the size and shape of the debris cloud," NASA-JPL explained in a blog post on Friday.

According to the researchers, the amount of infrared brightening Spitzer saw suggests only a small portion of the cloud passed in front of the star and that the debris from this collision covered an area hundreds of times larger than that of the star.

Over the next few months, the large dust cloud grew in size and became more translucent and by 2019, the cloud that passed in front of the star was no longer visible, but the system contained twice as much dust as it had before Spitzer spotted the cloud.

The team believe that the information can help scientists test theories about how terrestrial planets form and grow.

"Learning about the outcome of collisions in these systems, we may also get a better idea of how frequently rocky planets form around other stars," said lead author Su.

The study is published in the Astrophysical Journal.