THIS WEEK IN SCIENCE:
This week in science, astronomers have discovered TW Hydrae a new-born solar system containing enough water vapor to fill all of Earth’s oceans a thousand times. The system was discovered by a team using the European Space Agency’s Herschel Space Observatory, a telescope orbiting 930,000 miles above the Earth.
Solar systems form when giant molecular clouds, which are gravitationally unsound, break apart into smaller, denser clumps that collapse to form stars. As the disk collapses and contracts, it begins to spin faster and faster, like a figure skater who holds her arms close to her body to spin more quickly.
This spinning produces an accretion disk that feeds the central star, but it also produces a flat region perpendicular to the star, the way pizza dough thins out when it’s spun.
The material in the accretion disk will eventually form planets, comets, and asteroids, when the central star cools enough for the gas and particles to condense into rocks and dust. This is the stage that TW Hydrae is at now. Well, 175 years ago.
TW Hydrae is an orange dwarf star about 10 million years old and 175 light-years away. This is just about the age that planets and comets will start forming in the star’s accretion disk.
This is something like how our own Solar System formed somewhere around 4.5 billion years ago. “The detection of water sticking to dust grains throughout the disc would be similar to events in our own Solar System’s evolution, where over millions of years, similar dust grains then coalesced to form comets,” said Michiel Hogerheijde of Leiden University, the lead researcher of this study.
Finding water in space is not rare; there is water in moons like Europa and Enceladus, as well as in the Kuiper Belt (where icy objects like Pluto reside, in the outer portions of the Solar System). Halos of hot water vapor have been found in the accretion disks of other early solar systems, as well. This water vapor, however, is on the edge of the disk where it is cool, and where it can coalesce into icy comets.
When TW Hydrae finally forms planets, there is a good chance there will be a large amount of leftover water vapor, which will form into comets and, subsequently, crash into rocky, arid planets. This can create vast oceans on planets that are cool enough to keep the water, and massive enough to have an atmosphere to hold the water in. Just like Earth.
Scientists studying TW Hydrae hope that its similarity to our Sun will allow them to understand how our own Solar System came to be. According to Göran Pilbratt, an astronomer working on the projectt, “Here we are studying the ‘raw material’ for planet formation, which is fundamental to an understanding of how planetary systems such as our own Solar System once formed.”
By Ryan Barley
Special to the Beacon