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.
Instrument
LWS02
Temporal Coverage
1997-04-29T02:44:01Z/1997-08-24T03:38:20Z
Version
1.0
Mission Description
The Infrared Space Observatory (ISO) was the worlds first true orbiting infrared observatory. Equipped with four highly-sophisticated and versatile scientific instruments, it was launched by Ariane in November 1995 and provided astronomers world-wide with a facility of unprecedented sensitivity and capabilities for a detailed exploration of the Universe at infrared wavelengths.
European Space Agency, Stark et al., 1999, 'THE GAS-DUST CONNECTION AND COOLING IN PROTO-PLANETARY DISCS', 1.0, European Space Agency, https://doi.org/10.5270/esa-gqm0o19
