Astronomers have observed for the first time the birth of planets around a young star outside the solar system, resembling the formation of a new solar system. This marks the first time a planetary system in its early stages of formation has been discovered, opening a window for understanding the past of our own solar system.
The European Southern Observatory (ESO) announced in a press release on July 16 that astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile and the James Webb Space Telescope of NASA have observed the formation of initial planetary materials, such as newly forming hot minerals.
The lead author of the study, Assistant Professor Melissa McClure of Leiden University in the Netherlands, stated, “We have confirmed for the first time that planets are beginning to form around a star outside our solar system.”
Another author of the study, Professor Merel van ‘t Hoff from Purdue University in the United States, likened these findings to “baby pictures of the solar system,” saying, “The system we see looks like our solar system when it just started to form.”
The young star, named HOPS-315, is located approximately 1,300 light-years away from Earth and is similar to a newborn Sun. Around such young stars in the protostar stage (early stages of star formation), astronomers often observe circular disks of gas and dust known as protoplanetary disks, which are the birthplaces of new planets.
While astronomers have previously observed young disks containing massive, Jupiter-like protoplanets, McClure noted, “We have always known that the initial solid parts of a planet, also known as planetesimals, must have formed at an earlier time.”
In our solar system, the earliest solid materials condensed near the current orbit of Earth around the Sun have been found preserved in ancient meteorites. Astronomers age-date these primitive rocks to determine the time of solar system formation.
These meteorites are filled with crystalline minerals containing silicon dioxide, which can condense at extremely high temperatures in young planetary disks. The newly condensed solids aggregate over time, increasing in size and mass, laying the seeds for planet formation.
The first kilometer-sized planetesimals in the solar system eventually evolved into planets like Earth or the cores of Jupiter, formed after the condensation of these crystalline minerals.
In the study of HOPS-315, researchers found evidence of hot minerals condensing in a disk-like structure around the young star. The results indicate the presence of gaseous silicon dioxide both around the star and within these crystalline minerals, suggesting they are just starting to solidify.
Another author of the study, Professor Edwin Bergin from the University of Michigan, mentioned, “Such processes in the protoplanetary disk have never been seen before, either in our solar system or anywhere else outside it.”
Similarly, one of the study’s authors, postdoctoral researcher Logan Francis from Leiden University, stated, “The minerals we are observing in this extra-solar system are actually located in the same positions as those we see in small asteroids of our solar system.”
Therefore, the disk of HOPS-315 provides an excellent analogy for studying the cosmic history of our own universe. As van ‘t Hoff mentioned, “This system is one of the best-known and observable systems for studying some processes within our solar system.”
It also offers astronomers a new opportunity to study the early stages of planet formation, as it serves as a substitute for a newborn solar system within the galaxy.
The research findings were published on July 16 in the journal “Nature.”