Detectability of deuterated water in prestellar cores

摘要: Water is an important molecule in the chemical and thermal balance of dense molecular gas, but knowing its history through-out various stages star formation a fundamental problem. Its deuteration provides us with crucial clue to history. H$_2$O has recently been detected for first time towards prestellar core L1544 Herschel Space Observatory high spectral resolution (HIFI instrument). Prestellar cores provide original reservoir material from which future planetary systems are built, few observational constraints exist on water none before collapse starts protostar forms at centre. We report new APEX observations ground state 1$_{0,1}$-0$_{0,0}$ HDO transition 464 GHz L1544. The line undetected, we present extensive study conditions detectability cold cloud cores. deuterated abundances have estimated using advanced model simplified limited number reactions or processes that active regions (< 15 K). use LIME radiative transfer code compute expected intensity profile both lines compare them observations. several ad hoc profiles best-fit results astrochemical modelling, coupling gas phase grain surface chemistry. Our comparison between observations, transfer, modelling shows limits singly water, through ground-state transitions 1$_{1,1}$-0$_{0,0}$ 464.9 893.6 GHz, respectively, single-dish telescope interferometric