Water Water Everywhere In The Universe
Two widely different space research efforts reported results this week. Both involve the importance of water. The artistic rendering below is of a black hole with its accretian disc of material spinning around it and two jets of energetic particles radiating along the spin axis.
Two teams of astronomers have discovered the largest and farthest reservoir of water ever detected in the universe. The water, equivalent to 140 trillion times all the water in the world's ocean, surrounds a huge, feeding black hole, called a quasar, more than 12 billion light-years away.
"The environment around this quasar is very unique in that it's producing this huge mass of water," said Matt Bradford, a scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "It's another demonstration that water is pervasive throughout the universe, even at the very earliest times." Bradford leads one of the teams that made the discovery.
The astronomers were studying a quasar called APM 08279+5255 harboring a black hole 20 billion times more massive than the sun. They expected to find evidence of water in the distant early universe. But they were surprised by this amount. Our Milky Way contains 4000 times less water than this system.
Water vapor is an important trace gas that reveals the nature of the quasar. In this particular quasar, the water vapor is distributed around the black hole in a gaseous region spanning hundreds of light-years in size (a light-year is about six trillion miles). Its presence indicates that the quasar is bathing the gas in X-rays and infrared radiation, and that the gas is unusually warm and dense by astronomical standards. Although the gas is at a chilly minus 63 degrees Fahrenheit (minus 53 degrees Celsius) and is 300 trillion times less dense than Earth's atmosphere, it's still five times hotter and 10 to 100 times denser than what's typical in galaxies like the Milky Way.
Measurements of the water vapor and of other molecules, such as carbon monoxide, suggest there is enough gas to feed the black hole until it grows to about six times its size.
Asteroids Vesta and Ceres Have Water Histories
On July 18, the Dawn spacecraft send this image of the asteroid Vesta from an orbital distance of 6500 miles. Vesta and Ceres are the two largest asteroids. Their histories and compositions are quite different. Dawn will provide scientists the data to help them understand why they differ so much. Vesta is dry and cratered as shown. Ceres is wetter and appears to have a clay-like surface.
Vesta will be orbited by Dawn for the next year. At that time, it will use its ion engines to leave orbit and begin the journey to Ceres where it will also be place into orbit.
Water plays a significant role in our universe. A better understanding of that role is needed.
How Did Dawn Get There?
More details about the Dawn mission are available in this previous diary. It explains the purposes of the mission, the science instruments, the route traveled by Dawn since 2007, and the importance of the ion engine propulsion system it uses.