Far out cosmology: the source of solar system water (Introduction)

by David Turell , Thursday, March 09, 2023, 00:15 (408 days ago) @ David Turell

In the original protoplanetary disc:

https://www.sciencealert.com/astronomers-traced-the-origins-of-water-to-a-time-before-t...

"A star 1,300 light-years from Earth might have just revealed one of the Solar System's best-kept secrets.

"It's called V883 Orionis, a young star surrounded by a huge disk of material that will one day coalesce into orbiting planets. It's in that disk that scientists have made an unambiguous detection of water vapor, swirling around with all the other dust and gas destined to become part of an alien world.

"This suggests that the Solar System's water – including that now on Earth – was present in the gaseous cradle from which the Sun was born; that it was here, not just before Earth, but before the Sun, and helped our planet grow.

"We can now trace the origins of water in our Solar System to before the formation of the Sun," says astronomer John Tobin of the US National Radio Astronomy Observatory.

"Water is fairly common throughout the Universe, though Earth in particular wouldn't be the same "pale blue dot" without it. It curls around the planet's surface, permeates the atmosphere as vapor, falls down from the sky. It seems pretty mundane to us, but we wouldn't be able to live without it; almost all life's chemical processes require it.

"It's also an important ingredient in planet formation. Stars are born from clouds of dust and gas in space; a dense clump collapses under gravity and, spinning, starts spooling in more material from the cloud around it that forms into a disk that feeds into the baby star.

"Once the star is done growing, all the other features of the planetary system form from whatever remains of the disk. Dust grains stick together electrostatically, forming larger and larger clumps until the object is massive enough for gravity to take over.

"Water is thought to play a significant role in this process; beyond the point at which water vapor freezes – called the snowline – it coats dust grains as ice, giving them an additional stickiness that helps particles cling together in the very first stages of planetary growth.

***

"'V883 Orionis is the missing link in this case," Tobin says.

"'The composition of the water in the disk is very similar to that of comets in our own Solar System. This is confirmation of the idea that the water in planetary systems formed billions of years ago, before the Sun, in interstellar space, and has been inherited by both comets and Earth, relatively unchanged."

***

"'We conclude that disks directly inherit water from the star-forming cloud and this water becomes incorporated into large icy bodies, such as comets, without substantial chemical alteration," the researchers write in their paper.

"'Although the specific delivery mechanism of water on Earth remains debated (comets and/or asteroids), the [hydrogen isotope ratio] found in V883 Ori is evidence that the water molecules in our Solar System originated in the cold interstellar medium before the formation of the Sun. Therefore, spatially resolved water observations towards young planet-forming disks are crucial in linking the water reservoir and the formation of terrestrial planets.'"

Comment: water with all its strange properties is vital to life. No surprise it is ubiquitous in the universe. But note how much Earth has compared to Mars. Our magnetic field really helps.