This star offers the earliest peek at the birth of a planetary system like ours

The birth of a new solar system may have been caught on camera.

About 1,400 light-years from Earth sits a young sunlike star surrounded by cooling gas and teensy silicate minerals. These mineral solids — some of the building blocks of rocky planets — are among the first to condense from the gas, suggesting that they’re kick-starting the creation of planets in a system much like the one earthlings call home, researchers report in the July 17 Nature.

“It really is the first time we’ve seen this stage of planet formation in the process,” says planetary scientist Laura Schaefer of Stanford University, who was not involved in the new study. Observing the timeline of these early hot minerals will help researchers better understand how events unfolded billions of years ago in the solar system.

Clues about its earliest stages have primarily come from remnants of the incidents trapped in meteorites. The oldest space rocks suggest that the formation of certain minerals at very high temperatures starts the clock. This is the “t=0 moment,” says astronomer Melissa McClure of Leiden University in the Netherlands. “At this moment, the solar system first started to form, and then planets can form after this point.”

That activity takes place around other hot, baby stars, too, which reside in clouds of cold gas swirling with specks of rock and ice. Within a stellar nursery, a new star’s gravity pulls gas and dust toward it, and that material heats up until the solid grains vaporize. The hot stuff then spreads into a rotating protoplanetary disk that wraps around the star. It’s where seeds of planets emerge once the gas begins to cool and solids start to condense, McClure says.

Telescopes have mostly spotted such disks that are well beyond planets’ early formative years. However, previous observations of a young star dubbed HOPS 315, estimated to be around 100,000 to 200,000 years old and expected to swell to the mass of the sun, hinted that hot minerals marking the first stages of planets might lurk near it. “But we couldn’t really get a good feeling for which hot minerals these were,” McClure says.

She and her colleagues sought a better view of HOPS 315 and its surroundings using the James Webb Space Telescope and the Atacama Large Millimeter/submillimeter Array in Chile. The wavelengths of light absorbed and emitted by the protoplanetary disk revealed some interesting minerals and gas quite close to the star, within a distance comparable to that between the sun and the asteroid belt.

“The minerals that they’re seeing are similar to some of the very first materials that formed in our solar system,” Schaefer says.

The team identified silicon monoxide gas at about 200° Celsius, indicating it cooled from the temperatures at which the detected crystalline silicate minerals form. Computer simulations of one of those minerals, forsterite — which condenses at between around 600° C and 1000° C — suggest its grains quickly stick together and accumulate into fingernail-sized silicate mineral clusters, like those that have been uncovered in ancient meteorites, McClure says.

HOPS 315 also spits out a jet of gas from the protoplanetary disk, but it contains less silicon and iron than expected. McClure thinks that rocks bearing those elements — which can grow into planets — might be hidden from the researchers’ view. The detected silicate minerals and silicon monoxide may comprise leftovers from building the first preplanet clumps.

Since at least the late 1960s, scientists have suspected that this silicate production process occurs near budding stars, so it’s great to confirm it through observations, says cosmochemist Katharina Lodders of Washington University in St. Louis, who was not involved in the study.

“Planet formation is a pretty universal process,” she says. “What is seen around this young star should give scientists some ideas [about] what went on 4.6 billion years ago, when our solar system formed.”