Astronomers using the James Webb Space Telescope and the Chile-based Atacama Large Millimeter/submillimeter Array (ALMA) Telescope say they have witnessed the earliest stages of planets forming around protostar HOPS-315 in real time.
The researchers behind the discovery believe that witnessing the HOPS-315 system’s “dawn” around a protostar 1,300 light-years from Earth will inform planet formation models and could also shed light on the earliest stages of development in our solar system.
“For the first time, we have identified the earliest moment when planet formation is initiated around a star other than our Sun,” says Melissa McClure, a professor at Leiden University in the Netherlands and lead author of a study detailing the team’s findings.
Most astronomers agree that star systems in their earliest stages of development form a protoplanetary disc of material around a central proto- or baby star. As this material accretes together, protoplanets that ultimately form planets, moons, and other solar system objects such as comets and meteors begin to form.
Although scientists cannot travel back in time to witness planets forming around our nascent sun, the material from its protoplanetary disc, including the first solid material that formed the first stages of Earth, can be found inside ancient meteorites. By analyzing the age of these space rocks, astronomers have determined when the first seeds of planet formation in our solar system were planted.
For example, the crystalline material found inside such meteorites contains silicon monoxide (SiO), which condenses when exposed to high temperatures like those found in a protoplanetary disc. The resulting solid materials bind together like a rolling snowball, ultimately forming a solar system object, such as a planet.
According to McClure, scientists have known for a long time that planetesimals formed by the gathering of these solid materials “must form further back in time, at earlier stages.” However, astronomers had only witnessed protoplanetary discs with massive newborn gas giants, such as Jupiter, that were already formed. Now, the team says they have finally witnessed the creation of the first specks of planet-forming hot minerals, just beginning to solidify for the first time.
“This process has never been seen before in a protoplanetary disc — or anywhere outside our Solar System,” says co-author Edwin Bergin, a professor at the University of Michigan, USA.
The hints that SiO crystalline minerals were present around a baby star in a gaseous state were first detected by the James Webb Space Telescope. The data also suggested that the minerals were only just beginning to solidify.
To narrow down the location of the SiO signals, the team gathered observations of the system with ALMA. After comparing the JWST data with ALMA, the team determined that the signals originated from the disc region around HOPS-315. Logan Francis, a postdoctoral researcher at Leiden University and a co-author of the study, noted the tantalizing similarity of this location to our solar system.
“We’re really seeing these minerals at the same location in this extrasolar system as where we see them in asteroids in the Solar System,” he said.
The research team stated that because HOPS-315 is an analogue of the nascent Sun, observing the first stages of planet formation around it provides a rare glimpse into the processes that may have created our own solar system.
“We’re seeing a system that looks like what our Solar System looked like when it was just beginning to form,” study co-author Merel van ‘t Hoff, a professor at Purdue University, said, comparing their findings to a picture of the baby Solar System. “This system is one of the best that we know to actually probe some of the processes that happened in our Solar System.”
ESO astronomer and European ALMA Programme Manager Elizabeth Humphreys, who did not take part in the study, said she was impressed by the team’s findings, and also thought it could offer previously unavailable insights into our solar system’s formation.
“This result highlights the combined strength of JWST and ALMA for exploring protoplanetary discs,” Humhreys added.
Christopher Plain is a Science Fiction and Fantasy novelist and Head Science Writer at The Debrief. Follow and connect with him on X, learn about his books at plainfiction.com, or email him directly at christopher@thedebrief.org.