The specter of the old carbon -rich star known CW Leonis 10 216 or IRC has revealed the presence of water vapor at a temperature of 700 º C in the hot interior region of its gaseous envelope . This was confirmed this week Nature an international team of Canadian and European scientists , led by Leen Decin of the Catholic University of Leuven (Belgium ) and the researchers who participated Centre for Astrobiology ( CAB, CSIC- INTA joint center ).

CW Leonis is a red giant star , rich in carbon and water vapor in its atmosphere , located in the constellation Leo , 500 light years from Earth. With a radius of 500 soles , is the brightest extrasolar object in the sky in the infrared. The discovery was made possible thanks to data collected with the Herschel Space Observatory, European Space Agency ( ESA).

“Until now we knew that these atmospheres contain water molecules or molecules of carbon, and it was thought that these two types of molecules could not coexist. Thanks to Herschel satellite measurements have shattered that theory so far established as a star like CW LeonisVery rich in carbon and characterized by the presence of large carbon chains as C8H , is able to have abundant water vapor in areas of high internal atmosphere , “says researcher CSIC José Cernicharo .

The main elements of life on Earth are water and carbon , and stars like the sun ‘s synthesized in large quantities when they reach the end of their lives . When older, these stars become red giants, as CW LeonisAnd eliminate their atmospheres.

CW Leonis currently emits 10,000 times more energy than the Sun and its interior are produced nuclear fusion reactions that convert helium into carbon. Much of this carbon ends up in the outer layers of the atmosphere in the form of stellar wind (rich in molecules and dust particles with carbon-based ), similar to the solar wind on Earth, but then released a billion times more stuff every hour. Within thousands of years, CW Leonis will become a white dwarf surrounded by a planetary nebula, a cloud of gas and dust formed by the material present in the atmosphere today.

Rethinking theories

With so much carbon in its atmosphere , almost all the oxygen should be enclosed in carbon monoxide, and would imply an absence of water. However, the researchers found in 2001 that the star produced in a given emission wavelength , demonstrating the existence of water vapor. A possible origin was proposed that the stellar wind of water molecules released a cloud of icy comets located around the star .

” Herschel has undoubtedly detected the presence of water at many wavelengths , and it is now possible to establish that the water vapor temperature is between 700 and 1000 degrees Celsius, which means that water vapor is formed in the inner layers of the atmosphere and is distributed through the stellar wind , “explains Cernicharo .

The model of stellar wind interacting with the cloud of a distant icy comet must be replaced by one in which stipulate that water vapor is created by chemical reactions processes that are triggered by ultraviolet radiation . The ultraviolet light breaks the carbon monoxide , liberating oxygen atoms that can react with hydrogen to form water molecules.

“The only possible source of ultraviolet light is interstellar space , but would normally be blocked by the material flowing from the star . The Herschel satellite observations have shown that some regions around CW Leonis should be almost empty, allowing ultraviolet light reaches the deeper layers of the star ‘s atmosphere and initiate chemical reactions that produce water , “said Cernicharo .

Herschel results imply that similar processes occur around red giant stars as the study, which continue to supply material for new generations of stars and planets in galaxies like the Milky Way. The chemical models developed by researchers at the CAB Marcelino and Jose Cernicharo Agundez began to raise more than 20 years and predicts the presence of large amounts of water vapor in any type of red giant star .

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Citation :

L. Decin , M. Agundez , M. J. Barlow , F. Daniel , J. Cernicharo , R. Lombaert , E. De Beck , P. Royer , B. Vandenbussche , R. Wesson , E. T. Polehampton , J. A. D. L. Blommaert , W. De Meester , K. Exter, H. Feuchtgruber W. K. Gear, H. L. Gomez , M. A. T. Groenewegen , M. Guélin , P. C. Hargrave , R. Huygen , P. Imhof , R. J. Ivison , C. Jean , C. Kahane , F. Kerschbaum , S. J. Leeks , T. Lim, M. Matsuura , G. Olofsson , T. Posch , S. Regibo , G. Savini , B. Sibthorpe , B. M. Swinyard , J. A. Yates & C. Waelkens . Vapour Warm water in the outflow from a luminous sooty carbon star . Nature 467, September 2, 2010 . Doi : 10.1038/nature09344 .

Source: CSIC