- Astronomers say they've witnessed the formation of an exoplanet in sharper detail than ever before.
- The astronomers spotted the newly formed exoplanet amidst a disk of gas and dust surrounding the star AB Aurigae, which lies about 520 light-years from Earth.
- The team observed the protoplanet using the SPHERE instrument on European Southern Observatory’s Very Large Telescope in Chile.
Astronomers have snapped the most detailed pictures of the birth of an exoplanet yet. Surrounded by a dense cloud of gas and dust, the hatchling world orbits the star AB Aurigae, found 520 light-years from Earth in the constellation Auriga (The Charioteer).
Planets form in protoplanetary disks around newly formed stars. Astronomers believe they're shaped through the accumulation of millions of tiny grains of chilled gas and dust, pressed together by the forces of gravity. (Imagine tossing a snowball down a hill. In a sense, it's a similar process.) These tiny, clumpy planetesimals grow larger and larger as they gobble up gases and dust along their orbit. Eventually, they become planets.
Astronomers have catalogued over 4,000 exoplanets across the universe but have never seen one form—until now. The key to spotting this process is tracking the right type of star. “We need to observe very young systems to really capture the moment when planets form,” astronomer Anthony Boccaletti, of the Observatoire de Paris at PSL University in France, said in a statement.
In 2018, researchers released images of AB Aurigae taken with the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile. When Boccaletti and his colleagues saw the images, which featured two spiraling arms of dust swirling close to the star, they decided to take a closer look using the SPHERE instrument on the European Southern Observatory’s Very Large Telescope in Chile.
SPHERE uses a technique called high-contrast imaging, slowly teasing out super faint traces of light from around young stars over the course of several hours of continuous observation. This way, astronomers can view the tiny planet from multiple angles.
Images of the protoplanetary disk surrounding AB Aurigae revealed the telltale signs that a planet might be forming. Theoretical models suggest that as planets form, they tend to kick the gas around them, causing "disturbances in the disc in the form of a wave, somewhat like the wake of a boat on a lake,” Emmanuel Di Folco, of the Astrophysics Laboratory of Bordeaux (LAB), France, explained in the statement. The astronomers also spotted a strange twist in the cloud of dust, further marking the spot where the planet is forming.
The scientists—from France, Taiwan, Belgium, and the U.S.—recently published their study in the journal Astronomy and Astrophysics. The findings, they say, shed light on how this mysterious process unfolds in other star systems.
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