Much of Earth's Water Is Older Than the Sun

[Buster's Uncle]

Much of Earth's Water Is Older Than the Sun
SPACE.com
by Mike Wall, Senior Writer  25 minutes ago



Planets form in the presence of abundant interstellar water inherited as ices from the parent molecular cloud.



Much of the water on Earth and elsewhere in the solar system likely predates the birth of the sun, a new study reports.

The finding suggests that water is commonly incorporated into newly forming planets throughout the Milky Way galaxy and beyond, researchers said — good news for anyone hoping that Earth isn't the only world to host life.

"The implications of our study are that interstellar water-ice remarkably survived the incredibly violent process of stellar birth to then be incorporated into planetary bodies," study lead author Ilse Cleeves, an astronomy Ph.D. student at the University of Michigan, told Space.com via email.

"If our sun's formation was typical, interstellar ices, including water, likely survive and are a common ingredient during the formation of all extrasolar systems," Cleeves added. "This is particularly exciting given the number of confirmed extrasolar planetary systems to date — that they, too, had access to abundant, life-fostering water during their formation."

Astronomers have discovered nearly 2,000 exoplanets so far, and many billions likely lurk undetected in the depths of space. On average, every Milky Way star is thought to host at least one planet.


Water, water everywhere

Our solar system abounds with water. Oceans of it slosh about not only on Earth's surface but also beneath the icy shells of Jupiter's moon Europa and the Saturn satellite Enceladus. And water ice is found on Earth's moon, on comets, at the Martian poles and even inside shadowed craters on Mercury, the planet closest to the sun.



Artist's concept showing the time sequence of water ice, starting in the sun's parent molecular cloud, traveling through the stages of star formation, and eventually being incorporated into the planetary system itself.


Cleeves and her colleagues wanted to know where all this water came from.

"Why is this important? If water in the early solar system was primarily inherited as ice from interstellar space, then it is likely that similar ices, along with the prebiotic organic matter that they contain, are abundant in most or all protoplanetary disks around forming stars," study co-author Conel Alexander, of the Carnegie Institution for Science in Washington, D.C., said in a statement.

"But if the early solar system's water was largely the result of local chemical processing during the sun's birth, then it is possible that the abundance of water varies considerably in forming planetary systems, which would obviously have implications for the potential for the emergence of life elsewhere," Alexander added.


Heavy and 'normal' water

Not all water is "standard" H2O. Some water molecules contain deuterium, a heavy isotope of hydrogen that contains one proton and one neutron in its nucleus. (Isotopes are different versions of an element whose atoms have the same number of protons, but different numbers of neutrons. The most common hydrogen isotope, known as protium, for example, has one proton but no neutrons.)

Because they have different masses, deuterium and protium behave differently during chemical reactions. Some environments are thus more conducive to the formation of "heavy" water — including super-cold places like interstellar space.

The researchers constructed models that simulated reactions within a protoplanetary disk, in an effort to determine if processes during the early days of the solar system could have generated the concentrations of heavy water observed today in Earth's oceans, cometary material and meteorite samples.

The team reset deuterium levels to zero at the beginning of the simulations, then watched to see if enough deuterium-enriched ice could be produced within 1 million years — a standard lifetime for planet-forming disks.

The answer was no. The results suggest that up to 30 to 50 percent of Earth's ocean water and perhaps 60 to 100 percent of the water on comets originally formed in interstellar space, before the sun was born. (These are the high-end estimates generated by the simulations; the low-end estimates suggest that at least 7 percent of ocean water and at least 14 percent of comet water predates the sun.)

While these findings, published online today (Sept. 25) in the journal Science, will doubtless be of interest to astrobiologists, they also resonated with Cleeves on a personal level, she said.

"A significant fraction of Earth's water is likely incredibly old, so old that it predates the Earth itself," Cleeves said. "For me, uncovering these kinds of direct links between our daily experience and the galaxy at large is fascinating and puts a wonderful perspective on our place in the universe."


http://news.yahoo.com/much-earths-water-older-sun-182243912.html

[Buster's Uncle]

Study finds solar system’s water older than the sun
Reuters
By Irene Klotz  1 hour ago



CAPE CANAVERAL Fla (Reuters) - Water found in Earth’s oceans, in meteorites and frozen in lunar craters predates the birth of the solar system, a study published on Thursday shows, a finding with implications for the search for life on other planets.

Scientists have long debated whether the solar system’s water came from ice ionized during the formation of the solar system, or if it predated the solar system and originated in the cold interstellar cloud of gas from which the sun itself was formed.

The study was published in this week’s issue of the journal Science.

“It's remarkable that these ices survived the entire process of stellar birth,” lead researcher Lauren Cleeves, told Reuters.

Cleeves, a doctoral student at the University of Michigan, had been studying how radioactivity, galactic cosmic rays and other high-energy phenomena impact planet-forming disks of matter that circle young stars.

The “aha” moment, she said, was realizing that conditions in the early solar system weren’t right for synthesizing new water molecules.

“Without any new water creation, the only place these ices could have come from was the chemically rich interstellar gas out of which the solar system formed,” she said.

To prove the point, she and colleagues ran computer models comparing ratios of hydrogen with its heavier isotope, deuterium, which has been enriching the solar system’s water over time.

To reach the ratios found in meteorite samples, as well as in Earth's ocean water and comets, at least some of the water would have had to be formed before the sun’s birth, the scientists concluded.

The process likely would be the same for other solar systems as well, suggesting conditions hospitable for life could exist beyond Earth.

Also this week, a second paper in Science notes the discovery of a branched carbon-containing molecule involved in the creation of stars.

The molecule, known as iso-propyl cyanide (i-C3H7CN), was discovered in a giant gas cloud called Sagittarius B2, the most massive star-forming region in the Milky Way, by Chile’s ALMA observatory.

"Understanding the production of organic material at the early stages of star formation is critical to piecing together the gradual progression from simple molecules to potentially life-bearing chemistry," lead researcher Arnaud Belloche, with the Max Planck Institute for Radio Astronomy in Germany, said in a statement.

(irene.klotz@thomsonreuters.com; editing by Andrew Hay)


http://news.yahoo.com/study-finds-solar-system-water-older-sun-180218419.html

[Buster's Uncle]

Up to half of Earth's water is older than Sun
AFP
25 minutes ago



Findings suggest that at least some of the water in the solar system comes from outer space, and that water is not unique to our solar system (AFP Photo/Joe Raedle)



Washington (AFP) - Up to half the water on Earth is likely older than the solar system, raising the likelihood that life exists elsewhere in the galaxy, according to a study Thursday.

The research in the journal Science found that "a significant fraction" of the water on Earth was inherited from interstellar space, and was there before the Sun was formed some 4.6 billion years ago.

Researchers can tell where the water comes from by examining the ratio of hydrogen to deuterium, a heavy isotope of hydrogen, in water molecules.

Water or ice that comes from interstellar space has a high ratio of deuterium to hydrogen, because it forms at such low temperatures.

But scientists have not known how much deuterium was removed in the process of the Sun's birth, or how much deuterium-rich water-ice the solar system would have produced when it was first born.

Scientists simulated the origin of a planet under conditions where all the deuterium from space ice has already been eliminated.

They found they could not reach the ratios of deuterium to hydrogen that are found in meteorite samples or Earth's ocean water.

Their findings suggests that at least some of the water in the solar system comes from outer space, and that water -- an essential element for life on Earth -- is not unique to our solar system.

"This is an important step forward in our quest to find out if life exists on other planets," said co-author Tim Harries, from the University of Exeter's Physics and Astronomy department.

"It raises the possibility that some exoplanets could house the right conditions, and water resources, for life to evolve."


http://news.yahoo.com/half-earths-water-older-sun-215812677.html