with known distances and metallicities and with a wide range of age, globular clusters (gcs) in the magellanic clouds (mcs) offer an excellent opportunity for observational studies of stellar evolution. in order to make clear the evolution of late stages of stars and, especially, the mass-loss phenomenon and its effects on stellar evolution, we proposed in our gt proposal, ttanabe.redstar3, to observe systematically the gcs in the mcs using 3 lw filters of isocam. several gcs have already been observed with iso and our preliminary analysis shows that there is at least one very red, infrared stars in each of ngc 1978 and ngc 1846 which are both intermediate-age clusters. these stars are very red and invisible even at k-band. they are thought to be luminous agb stars which clearly stand apart from the other, visible, agb stars in that they have much thicker dust shells resulting from heavier mass-loss. we thus believe that they are in the final stage of their agb evolution, the superwind phase. if so, we have a very good chance to study stars in this phase because their ages and masses can be estimated. we here propose to observe spectrophotometrically these infrared stars in ngc 1978 and ngc 1846 with isocam cvf and isopht. iso observations will enable us with the full spectral energy distributions of these stars up to 60 microns, which enables us to determine their luminosity accurately as well as their spectral types. the mass of dust shell and the mass-loss rate can also be estimated. with these information we can elucidate the nature of the stars in the late evolutionary stage and the mass-loss phenomenon. all these can be used to test the current theory of stellar evolution. although this is not a proposal to request more time, we think that this proposal is the extension of our open time proposal, ttanabe.mcclus, which is (was) to observe ngc 1783 and ngc 419 in the same way as this proposal.
Instrument
CAM01 , CAM04 , PHT03
Temporal Coverage
1997-09-29T08:47:31Z/1997-10-07T00:35:16Z
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, TANABE et al., 1998, 'SPECTROPHOTOMETRIC OBSERVATIONS OF AGB STARS IN THE MAGELLANIC CLOUDS STAR CLUSTERS II', 1.0, European Space Agency, https://doi.org/10.5270/esa-5hyjco4
