Water Signatures in Protostars

Water signatures in protostars have been observed already 30 years ago. Hydroxyl and Water Masers in Protostars were discussed e.g. by Litvak, 1969 [204]. The first detection of interstellar water molecules was made by Cheung et al., 1969 [67]. They analyzed the 1.35 cm microwave emission in the sources Sgr B 2, Orion and W 49. For numerical calculations, de Jong, 1973 [100] used the abundance of water relative to hydrogen as 10 that means for 10 molecules or atoms of hydrogen there is one H2O molecule. 

Giant planet formation using shallow water simulations of a gaseous protostellar disk was investigated by Zajac, Ingersoll and Dowling, 1991 [371]. They considered vortices in Jupiter s atmosphere. High pressure vortices form spontaneously there and they are stable in an unstable shear flow. They rotate opposite to the sense of 

Codella and Palla, 1995 [71] reported on a search for water masers in protostellar disks. 160 IRAS sources were selected which define high-mass star forming regions. Water maser emission was found in 11 sources of this sample. This could mean that the population of OB-stars was overestimated by 50%. 

The water maser emission associated with the infrared centers IRS 1 and IRS 3 of the NGC 207 HR star-forming region was studied by Seth, Greenhill, and Holder, 2002 [305]. They used water masers as tracers for protostellar disks. NGC 2027 is a reflection nebula in the constellation of Orion. 

The young stellar object W33A which is deeply hidden protostar was studied in the wavelength range 2.4-25 pm. The spectrum displays deep H2O ice absorptions centered at 3.0 pm. A value for the H2O ice column density could be derived N(H20) = (1.1 0.3) X lOi cm-2 (Gibb et al., 2000 [139]). 

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