It was previously reported that two young giant gas planets called PDS 70b and PDS 70c were orbiting a young star located about 370 light-years away from us in the constellation Centaurus. Another recent report revealed that planet PDS 70b, which was about the same size as Jupiter, was still growing. In fact, its mass is approximately five times that of Jupiter and if it continues growing at its current rate, it would gain another 1/100th of Jupiter’s mass in the following million years.
And now there is more news regarding that system as for the first time ever, astronomers have definitively found a moon-forming disk surrounding an exoplanet. What this means is that there could be several moons in the process of forming around PDS 70c. Actually, experts have revealed that there is enough material in that disk to form three moons about the size of the one that orbits Earth. It’s important to note that the other planet, PDS 70b, does not have a disk around it.
The circumplanetary disk that surrounds PDS 70c is approximately 500 times bigger than the rings of Saturn. By using the Atacama Large Millimeter/submillimeter Array (ALMA) at the European Southern Observatory (ESO) in Chile’s Atacama Desert, scientists were able to determine that the disk’s diameter measures approximately 1 astronomical unit which is the distance between Earth and our sun (about 93 million miles or 150 million kilometers).
Since PDS 70c is still very young at 5 million years of age, experts will have a very rare opportunity to learn more about planets and moons in their infant stages. In a statement, Miriam Keppler, who is a researcher at the Max Planck Institute for Astronomy, went into further details by noting, “More than 4,000 exoplanets have been found until now, but all of them were detected in mature systems,” adding, “PDS 70b and PDS 70c, which form a system reminiscent of the Jupiter-Saturn pair, are the only two exoplanets detected so far that are still in the process of being formed.”
It is believed that planets form from dusty disks surrounding young stars and after they are created, a circumplanetary disk of dust and gas can surround those worlds which collide together to eventually form moons. But scientists have never been able to watch the process happen and that’s why the disk around PDS 70c is so important. (Pictures of the moon-forming disk surrounding PDS 70c can be seen here and here.)
The study was published in The Astrophysical Journal Letters where it can be read in full.