Located in the constellation Taurus, very close to Earth, HL Tauri is twice as massive as the Sun. The proximity allows us to have a precise photograph of the cluster of gas and dust around the star which allows planets to form.
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The ALMA radio-astronomical telescope has provided the first detailed images of water molecules in the disk where planets can be born from the very young star HL Tauri, according to a study published Thursday February 29 in the journal Nature Astronomy. “I never imagined that we could get an image of an ocean of water vapor in the very region where a planet is likely to form”commented Stefano Facchini, astronomer at the University of Milan, and first author of the study.
Located in the constellation Taurus and very close to Earth “only” 450 light years away, HL Tauri, twice as massive as the Sun, has long been in the crosshairs of terrestrial and space telescopes. Because its proximity and its youth (a million years at most) offer a breathtaking view of its protoplanetary disk, the cluster of gas and dust surrounding a star which allows planets to form.
The first to define this border
According to theoretical models, this formation process would be particularly fruitful at a very specific location on the disk: the ice line. Where water, which is in the form of vapor near the star, changes to a solid state as it cools. The dust grains would coagulate with each other all the more easily thanks to the ice covering them. As early as 2014, ALMA had produced unparalleled images of the protoplanetary disk, showing alternation of bright rings and dark furrows. The latter would betray the presence of embryos of planets forming by accumulation of dust.
Other instruments had detected water around HL Tauri, the study recalls, but with too low a resolution to precisely delineate the ice line. From its high altitude location, at more than 5,000 m, in the Chilean Atacama Desert, the European Southern Observatory (ESO) radio telescope is the first to identify this boundary. “To date, ALMA is the only facility capable of spatially resolving the presence of water in a cold planet-forming disk”claimed Professor Wouter Vlemmings, co-author of the study, quoted in a press release.
