FIRST DETECTION OF WATER VAPOR IN A PRE-STELLAR CORE
By P. Caselli, E. Keto, E. Bergin, M. Tafalla, Y. Aikawa, T. Douglas, L. Pagani, U. Yildiz, F. V. D. van der Tak, C. Walmsley and 4 more. 2012
159 citations recorded by the source corpus.
Water is a crucial molecule in molecular astrophysics as it controls much of the gas/grain chemistry, including the formation and evolution of more complex organic molecules in ices. Pre-stellar cores provide the original reservoir of material from which future planetary systems are built, but few observational constraints exist on the formation of water and its partitioning between gas and ice in the densest cores. Thanks to the high sensitivity of the Herschel Space Observatory, we report on the first detection of water vapor at high spectral resolution toward a dense cloud on the verge of star formation, the pre-stellar core L1544. The line shows an inverse P-Cygni profile, characteristic of gravitational contraction. To reproduce the observations, water vapor has to be present in the cold and dense central few thousand AU of L1544, where species heavier than helium are expected to freeze out onto dust grains, and the ortho:para H2 ratio has to be around 1:1 or larger. The observed amount of water vapor within the core (about 1.5 × 10−6 M☉) can be maintained by far-UV photons locally produced by the impact of galactic cosmic rays with H2 molecules. Such FUV photons irradiate the icy mantles, liberating water vapor in the core center. Our Herschel data, combined with radiative transfer and chemical/dynamical models, shed light on the interplay between gas and solids in dense interstellar clouds and provide the first measurement of the water vapor abundance profile across the parent cloud of a future solar-type star and its potential planetary system.
Subfields: Astronomy and Astrophysics, Spectroscopy
View Paper: https://www.semanticscholar.org/paper/effbb4d21abdf6aad930eb6859c6712953a6143e
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Citations in the corpus
- Formation of complex organic molecules in cold objects: the role of gas-phase reactions (2015, background): “Therefore, methanol is ejected from the grain mantles into the gas because of some non-thermal ice desorption, as it was previously claimed for water (Caselli et al. 2012).”
- Our astrochemical heritage (2012, methodology): “…of water vapor toward a prestellar core with the Herschel Space Observatory and the use of chemical/dynamical/radiative transfer models, allowed (Caselli et al. 2012) to measure a total mass of water vapor of 0.5 Earth masses within the central 10,000 AU and predicted about 2.6 Jupiter masses…”