The following document lists the file abstract/RSTARK_MS_GAS.abs
from catalogue VI/111.
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We propose to observe the circumstellar fine structure emission lines of [CII] 158 mu, and [OI] 63 mu and 146 mu towards a sample of three main-sequence stars which are resolved at 60 mu by IRAS. The LWS will be used in its highest spectral resolution mode in order to separate the contribution from the photosphere and the warm ISM. This study will provide important information on the physical properties of the circumstellar gas, the gas evolution, and its relation with the particle discs which are well studied within the ISO central programme. Together with the continuum measurements proposed by others in the central programme, we will get a DIRECT measure of the cooling rate of the circumstellar discs. Deep observations of the [CII] 158 mu line with the LWS Fabry-Perot are proposed of a sample of pre-main sequence Herbig Ae/Be stars in order to study the evolution of proto-planetary gas discs from young stellar objects to main sequence stars, as well as the cooling rate during the gas disc evolution. The sample has been taken from the central programme project of C. Waelkens et al., who will use both SWS and LWS in medium resolution mode. Their goal is to study the dust continuum, broad band solid state features and water-ice bands, and to determine the onset of the IR excess. Our proposal is therefore complementary to their study. In particular, it will provide answers to the question how and when giant planets are formed out of the gas phase, and what is the relation between the gas and the IR continuum emission.