The water molecule is a key ingredient in the formation of planetary systems. Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have detected water vapor in the disk around the young star HL Tauri exactly where planets may be forming. Their analysis implies a stringent lower limit of 3.7 Earth oceans of water vapor available within the inner 17 astronomical units of the HL Tauri system.
The water molecule is undoubtedly one of the most important molecular species in the whole Universe.
Being an extremely efficient solvent, water had a key role in the emergence of life as we know it on our planet.
For this reason, the chemical characterization of exoplanetary atmospheres is often focused on detecting this particular molecule.
Formed by the common hydrogen and oxygen atoms, water plays a fundamental role in the physics of the formation of planetary systems, due to its very high abundance in both gaseous and icy forms.
“I had never imagined that we could capture an image of oceans of water vapor in the same region where a planet is likely forming,” said Dr. Stefano Facchini, an astronomer at the University of Milan.
The HL Tauri system is thought to be less than 100,000 years old and about 17.9 billion km in radius. It lies in the direction of the constellation of Taurus at a distance of 450 light-years.
HL Tauri’s protoplanetary disk is unusually massive and bright, which makes it an excellent place to search for signs of forming planets.
The new ALMA observations revealed at least three times as much water as in all of Earth’s oceans in the inner part of the disk.
“It is truly remarkable that we can not only detect but also capture detailed images and spatially resolve water vapor at a distance of 450 light-years from us,” said Dr. Leonardo Testi, an astronomer at the University of Bologna.
The spatially-resolved observations with ALMA allow astronomers to determine the distribution of water in different regions of the…
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