They discovered a new connection between water and planet formation :: NASANET

A team of researchers has discovered water vapor in the disk surrounding the young star, precisely in the region where planets can form. Water is a key ingredient for life on Earth and is also believed to play an important role in the formation of planets. However, until now it has never been possible to map the distribution of water in a cold stable disk (the type of disk that provides the most favorable conditions for the formation of planets around stars). New discoveries were made possible thanks to the ALMA observatory in Chile.

“I never imagined that we would be able to image oceans of water vapor in the same region where a planet is likely forming,” says Stefano Facchini, an astronomer at the University of Milan, Italy, who led the study, published in the journal. Natural astronomy. In the inner disk of the young star HL Tauri, similar to the Sun and located 450 light-years from Earth (in the constellation Taurus), observations showed the presence of at least three times more water than all the planets. .

“It’s really impressive that we can not only detect, but also capture detailed images and spatially resolve water vapor as far as 450 light-years away,” adds co-author Leonardo Testi, an astronomer at the University of Bologna (Italy). . ALMA’s “spatial resolution” observations allow the astronomical community to determine the distribution of water in different regions of the disk.

“Participating in such an important discovery of the iconic HL Tauri disk exceeded all my expectations from my first research experience in astronomy,” adds Mathieu Vander Donkt from the University of Liège, Belgium, who was a master’s student. in the study.

The astronomical community knows that there is a gap in the disk of HL Tauri, and it is there that a significant amount of water has been discovered. These radial holes, observed in gas- and dust-rich disks, are created by young planet-like bodies as they accumulate material and grow. “Our recent images show significant amounts of water vapor at various distances from the star, including the space where a planet may currently be forming,” states Facchini. This suggests that this water vapor may influence the chemical composition of planets forming in these regions.

Observing water with a ground-based telescope is not an easy task, as the abundant water vapor present in the Earth’s atmosphere degrades astronomical signals. ALMA, managed by ESO together with its international partners, is a telescope array located in the Chilean Atacama Desert, at an altitude of approximately 5,000 metres, which was built in a high-altitude, dry environment precisely to minimize this degradation and provide exceptional observing conditions. “To date, ALMA is the only facility capable of spatially resolving water in the cold disk that forms the planet,” says co-author Wouter Vlemmings, a professor at Chalmers University of Technology in Sweden.

“It’s very interesting to see directly in the image how water molecules are released from the ice dust particles,” explains Elizabeth Humphreys, an ESO astronomer who was also involved in the study. The dust grains that form the disk are the seeds of planet formation. They collide and group into ever larger bodies orbiting the star. The astronomical community believes that where temperatures are low enough for water to freeze and form dust particles, objects come together more efficiently (an ideal environment for planet formation). “Our results show how the presence of water can influence the development of a planetary system, just as it did about 4.5 billion years ago in our solar system,” Facchini adds.

Thanks to upgrades being carried out at ALMA and ESO’s Extremely Large Telescope (ELT), which will be launched this decade, we will be able to understand much better both the process of planet formation and the role that water plays in it. In particular, METIS, a mid-infrared spectrograph and ELT imager, will provide the astronomical community with unprecedented views of the inner regions of planetary disks where Earth-like planets form.