scientific abstract the winds and mass-ejections from luminous stars strongly influence the evolution of massive stars and their surrounding circumstellar and interstellar matter. we propose to study the stellar winds and their circumstellar envelopes in a few stars of different sequential evolutionary stages by means of iso spectroscopic, photometric and imaging observations. the stages are: o-supergiants, b-supergiants, luminous blue variables and rapidly rotating be-supergiants. the stellar winds of hot stars are characterized by high terminal velocities (10^3 to 3.5 10^3 km/s) and a rapid acceleration. the sws grating will resolve the line profiles in hot supergiants and so the velocity field can be studied. the infrared hydrogen and helium recombination lines are formed in layers of the wind where the acceleration takes place and therefore offer an opportunity to study the radiation driven wind mechanism in detail. this information cannot be obtained from uv observations because the uv resonance lines are often saturated near line centre. also the ir recombination lines are much easier to model than the balmer emission lines in the optical. the ir emission lines also provide a measurement of the mass loss rate of the star which does not depend strongly on the details of the ionisation structure of the wind. therefore these data will give more accurate determinations of the mass loss rate than the uv resonance lines of ions of trace elements as c iv and si iv. furthermore it is expected that forbidden lines are present in the ir spectra which will allow an abundance study of the ejecta. evolutionary calculations predict that the surface abundance of he and n increase as the star strips more and more of its envelope by means of mass loss. therefore abundance determinations provide a critical test of these evolutionary calculations and of the mass loss history of the star. these measurements are especially meaningful for the ejecta around luminous blue variables (lbv.s) since these objects are thought to be the immediate progenitors of wolf-rayet stars. observation summary. we plan to observe hi and hei recombination lines and forbidden line transitions in our targets using sws grating aot06 and in four objects aot01 for full grating scans at reduced resolution. in addition we request pht-s spectra for all targets. we also request pht-c measurements at selected wavelengths (60, 90, 160 and 200 microns) of several stars. finally we request a cam aot01 observation of p cygni using the cvf at the ne ii 12.8 mu line with a 6 p.f.o.v. linelist for the aot06 observations: 4.0512\thi 5-4 br alfa 4.652 hi 7-5 pf beta 7.4579\thi 6-5 pf alfa 7.5005\thi 8-6 hu beta 8.7577\thi 10-7 11.3056\thi 9-7 12.3685 hi 7-6 hu alfa 12.3838 hi 11-8 16.2047 hi 10-8 16.8760 hi 12-9 19.0569 hi 8-7 22.3344 hi 11-9 27.7958 hi 9-8 38.8593 hi 10-9 4.243\thei 5-4 4.2947 hei 5-3 4.6053\thei 5-4 4.6936\thei 5-4 7.4351\thei 3-3 10.88\thei 4-4 12.37\thei 7-6 18.095\thei 4-4 43.944\thei 4-4 4.652\theii 14-10 7.205\theii 14-11 9.114\theii 15-12 12.367\theii 14-12 13.128\theii 11-10 17.261\theii 12-11 22.180\theii 13-12 34.649\theii 15-14
Instrument
PHT22 , PHT40 , SWS01 , SWS06
Temporal Coverage
1996-02-04T07:53:52Z/1997-02-17T14:57:57Z
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, Lamers et al., 1999, 'Winds and Circumstellar Matter around Hot Luminous Stars ', 1.0, European Space Agency, https://doi.org/10.5270/esa-ink89wg
