Astronomers Find A Bounty Of Baby Planets Hidden In The Dust Around Their Stars
These detections are consistent with nascent super-Earths and Neptune-sized exoplanets swirling around in the stars’ protoplanetary disks.
An exciting paper published today in the Astrophysical Journal announced the discovery of a treasure trove of planets, found lurking in the Taurus constellation. The newfound exoplanets reside 450 light-years away from Earth in a stellar nursery and were spotted with the help of the European Southern Observatory’s Atacama Large Millimeter/submillimeter Array (ALMA) stationed in northern Chile.
According to Phys.org, the newly discovered celestial bodies are baby planets that have only just begun to take shape. Their presence had been shrouded by the vast dust clouds surrounding their parent stars and was ultimately unraveled when the ALMA detected some rings and gaps within the accretion disks revolving around the stars.
Known as protoplanetary disks, these circular formations typically occur around newborn star. These dust disks are chock-full with planet-forming material and represent the fabric from which solar systems are fashioned — including our own.
The discovery was made by an international team of astronomers, who used the ALMA to examine 32 stars in the constellation’s star-forming region and found rings and gaps traced in the dust disks surrounding 12 of them.
These “dust substructures,” as the scientists refer to them in their paper, can only be explained if they were carved by unseen planets orbiting those particular stars. The team estimates that the nascent planets are super-Earths and Neptune-sized celestial bodies, which seem to form in greater numbers around young stars than previously believed.
“This is fascinating because it is the first time that exoplanet statistics, which suggest that super-Earths and Neptunes are the most common type of planets, coincide with observations of protoplanetary disks,” said study lead author Feng Long, a doctoral student at the Kavli Institute for Astronomy and Astrophysics at Peking University in Bejing, China.
The findings revealed that the baby planets are circling young stars of various masses and which sport both bright and faint protoplanetary disks. Some disks were even shown to harbor multiple rings and gaps, pointing at multi-planet systems in the making. These disks were typically “more massive and more extended” than others, the authors wrote in their paper.
While this is not the first time that astronomers have looked at protoplanetary disks around nearby stars, past studies focused on stars with the brightest disks — given that dust substructures are easier to pick up in these cases.
“Most previous observations had been targeted to detect the presence of very massive planets, which we know are rare, that had carved out large inner holes or gaps in bright disks,” said study co-author Paola Pinilla, a NASA Hubble Fellow at the University of Arizona’s Steward Observatory. “While massive planets had been inferred in some of these bright disks, little had been known about the fainter disks.”
The new study provides the first unbiased survey of nearby stars that are young enough to still be churning out planets, which were selected regardless of the brightness of their protoplanetary disks.
Although the team was unable to spot the baby planets individually due to the glaring light coming from these young stars, the astronomers managed to calculate an estimated size for these planets. Based on the size of the rings and gaps plowed through the dust disks of these 12 stars, the nascent planets are mostly Neptune-sized gas giants and rocky super-Earths up to 20 times the mass of our planet. In addition, two of the surveyed disks could be hiding Jupiter-sized behemoths rivaling the largest planet in our solar system.
“Since most of the current exoplanet surveys can’t penetrate the thick dust of protoplanetary disks, all exoplanets, with one exception, have been detected in more evolved systems where a disk is no longer present,” explained Pinilla.
Earlier this year, the ALMA detected three Jupiter-sized baby planets orbiting a young star some 330 light-years away from Earth, the Inquisitr reported in June. A few months later, ALMA picked up four giant planets the size of Jupiter and Saturn, floating in the protoplanetary disk of a star found 500 light-years from our planet, the Inquisitr reported in October.
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