The following document lists the file abstract/FKERSCHB_ORICHSRL.abs
from catalogue VI/111.
A plain copy of the file
(without headers/trailers) may be downloaded.
===================================================================== ==> In this proposal, more time is being requested for FKERSCHB.ORICHSRV ==> Time for this proposal is to be transferred from FKERSCHB.ORICHSRV ===================================================================== Systematic studies of the basic properties of type SRa and SRb Semiregular variables (SRVs) have found that SRbs consist of a "blue" group without circumstellar shells, short periods and higher temperatures and a "red" group with temperatures and mass loss rates comparable to Miras but periods a factor of 2 smaller. Near IR photometry shows that the "blue" SRVs are similar to non-variable giants, while the "red" SRVs are intermediate objects between Miras and normal giants. A subgroup of the Irregular variables of type Lb seem to be very similar to the "red" SRVs except for their lightcurves. The difference in atmospheric structure, most prominently seen in the strength of the water bands, could be due to smaller pulsation amplitudes and weaker shockfronts of the SRVs and Lbs. Thus, when compared to Miras and non-variable giants, the "red" SRVs and Lbs can provide important clues for the influence of the pulsational behaviour on the atmospheric structure and mass loss of AGB stars. Many of the theoretical tools for interpreting the spectra of these stars are available now. Since no detailed spectroscopic studies in the IR exist, we propose SWS spectra of selected objects. These will be compared with state of the art theoretical models. The SWS on board of ISO covers most of the molecular bands of H2O, CO and SiO and the wavelength region where continuous dust emission starts to dominate. While some of the mentioned bands can be observed from the ground, this requires different instruments and often excellent observing conditions. The use of different instruments generally means that different molecular bands and the dust emission cannot be studied at the same time, a severe disadvantage in view of the variability of AGB stars and the pronounced coupling between dust and different molecules.