(Artist’s impression of protoplanetary disk of TW Hydrae. Image: ESA / NASA / JPL-Caltech)

Scientists think that a good part of the water on our planet came aboard comets struck the Earth during its early formative stages. This hypothesis has been supported recently with the discovery by Herschel of water similar to Earth on a comet (103P/Hartley 2).

Now the same space telescope, thanks to the HIFI instrument has also detected water vapor emission throughout the disk swirling around TW Hydrae, a star formed about 5-10 million years and located at 176 light years the Earth. The discovery shows that there are significant reserves and water in protoplanetary disks surrounding some stars.

TW Hydrae is in the last stage of his training and is surrounded by a disk of dust and gas condensed to be completed to give rise to a whole system of planets.

The researchers believe that the emissions are produced when ultraviolet radiation heats the interstellar ice grains embedded in dust in the disc. This reserve of water could be an important contribution to the planets that form will be completed around this young star.

“The phenomenon could be similar to what happened in our own solar system, in which charged dust grains of ice were added to form comets,” says Michiel Hogerheijde the University of Leiden in the Netherlands, which has led the study. “We thought that comets were an important source of water for the planets in our solar system.”  

Simulations to find the volume of ice

Scientists have performed simulations that combine these new results with the observations made ​​above ground and with the data the telescope Spitzer at NASA, which has allowed them to calculate the volume of ice reserves the protoplanetary disk. The results indicate that the disk around TW Hydrae stored so much water that would fill several thousand oceans.

“We have already booked observation time of Herschel to study three protoplanetary disks around other stars, “confirms Hogerheijde. “We find similar results to those of TW Hydrae, even as now study objects that are up to three times farther away, it will take many more hours of observation.”

This research opens the door to a new understanding of the role of water in protoplanetary disks, and offers a new field of scientific tests to investigate how water came to our planet.

“With Herschel we can trace the water through every step of the process of formation of stars and planets, “says Göran Pilbratt, project scientist for Herschel to the ESA.

“In TW Hydrae are watching the ‘raw material’ from which new planets will eventually form, which helps us better understand how the Solar System formed in which we live,” explains the researcher.