The field of astronomy has witnessed a significant breakthrough with scientists observing a moon-forming region around an extraterrestrial planet, known as an exoplanet, for the first time. This discovery marks an essential advance in understanding the universe beyond our own solar system.
Understanding Exoplanets
Exoplanets, also known as extrasolar planets, are celestial bodies found outside of our solar system. The first confirmed detection of an exoplanet took place in 1992, and since then, over 4,400 have been discovered. Direct observation of these planets using telescopes is challenging due to the bright glare of the stars they orbit. Consequently, astronomers study exoplanets by assessing the effects they have on the stars they circle.
Key Findings: Observation and Detailed Study
Scientists have detected a disk comprised of swirling material accumulating around two exoplanets orbiting a young star named PDS 70, located about 370 light years from Earth. This disk, referred to as a circumplanetary disk, is responsible for moon birth.
The circumplanetary disk surrounding PDS 70c, one of the observed exoplanets, possesses enough mass to give rise to up to three moons similar in size to our moon. PDS 70c orbits its star at a distance approximately 33 times the length separating Earth from the sun, making it analogous to Neptune in our solar system.
The parent star, PDS 70, shares a comparable mass with our sun and is five million years old. Its two planets are even younger, and both are larger versions of Jupiter, a gas giant within our solar system. The moon-forming disk was observed around PDS 70c, and both planets are still in the process of acquiring their atmospheres.
Role of Advanced Instruments
The Atacama Large Millimeter/submillimeter Array (ALMA) observatory played a crucial role in this discovery. Located in Chile’s Atacama desert, the complex instrument is the most advanced astronomical observatory on Earth. The observatory, a combined effort from teams across North America, East Asia, and Europe, includes 66 high-precision dish antennas of varying sizes.
Circumplanetary Disks and Moon Formation
Before this discovery, no circumplanetary disks had been found due to the maturity of all known exoplanets. The two infant gas planets orbiting PDS 70, however, stand as exceptions. Saturn’s vast rings, which serve as an orbit for more than 80 moons, are remnants of a primeval moon-forming disk in our solar system.
The process by which stars form involves interstellar gas and dust coalescing around a new star. Circumplanetary disks surrounding planets subsequently yield moons. The dominant mechanism believed to drive planet formation is “core accretion,” where solid particles grow into larger bodies through collision and coagulation until they form a massive planetary embryo (10-20 Earth masses). Once it reaches this size, it can attract gas to form its atmosphere.
The same core accretion process that results in planets around a star also aids in the formation of moons around planets, further underscoring the dynamism and complexity of our universe.
