Astronomers are closer to figuring out how water ended up in an aging carbon star thanks to a new space telescope and some help from an Alberta company.
The chemical fingerprint of water vapour at about 700 degrees Celsius was found in a star called IRC+10216 using instruments on the Herschel Space Observatory, reports a paper to be published Thursday in Nature.
The find indicated the water is located in the warm, inner sooty region of the star's envelope and ruled out the possibility that it came from a nearby comet as previously suggested.
The Sun is a young star fuelled by the fusion of hydrogen into helium. But as it ages, it will run out of hydrogen, and the helium will begin combining into carbon.
The result will eventually be a carbon star — a bigger, hotter aging star rich in carbon.
Blue Sky Spectroscopy, a Lethbridge-based company, calibrated the instrument and developed data processing software that helped tease out the signals in the study, which was led by Leen Decin at the Katholieke Universiteit Leuven, Belgium. The company's work on the project was supported by funding from the Canadian Space Agency.
Researchers had detected a single signal for water around the star in 2001 — a surprising discovery because carbon stars were thought to have no oxygen-rich molecules around them except carbon monoxide (water contains two hydrogen atoms and one oxygen atom).
At the time, astronomers didn't have much more information because most useful water signals are in a region of the electromagnetic spectrum called the far infrared. Such signals are absorbed by Earth's atmosphere and therefore can't be seen from Earth, said Peter Imhof, research manager at Blue Sky Spectroscopy and a co-author of the paper.
The Herschel space telescope was launched in May 2009 and is positioned in space four times farther from the Earth than the Moon. That allowed it to provide access to dozens of other water signals.
"In space, you have a wide-open view," said Imhof, whose company specializes in research instruments and software to detect signals in the far infrared. "And now, you can start putting the pieces of the puzzle together."
Some signals are only produced at very high temperatures. Researchers were able to use that information to figure out the temperature of the water vapour and therefore its location within the star, which is hotter at its core and cooler at its edges.
The new information meant that the source of the water wasn't the vaporization of comets or dwarf planets, as previously thought. That would have released the water in outer areas of the star rather than the inner envelope. Several other theories were ruled out for the same reason.
The researchers suggested that water is likely formed from the combination of hydrogen with oxygen atoms freed up from certain carbon monoxide molecules by ultraviolet light. That chemical reaction can only take place if the temperature is high enough, but it's definitely hot enough in the part of the star where the water was found.
Imhof said he's excited by the results coming from the new telescope.
"This is really the strength of the space mission and the strength of the space instrument — that you get a whole whack of information in the same observation, which allows you to go much deeper," he said.