we are proposing to use iso to investigate the presence, and characterize the physical properties of dust around a selected sample of hot evolved stars populating the upper part of the hr diagram: lbvs, ofpe/wn9 and b[e] stars . some of these stars are known to show presence of dust in their circumstellar environment, from ground-based near-ir and iras data. the fact that dust grains do exist in the winds and/or in the close vicinities of these hot objects suggests that the conditions are present which increase the chances for the formation and survival of grains. it is clear then that determining the distribution and the properties of grains in these circumstellar shells will provide vital clues on the stars. modes of losing mass and, therefore, vital clues on their evolution. we will take advantage of iso.s unique capabilities to determine the properties and the distribution of this dust. we will use isocam to spatially resolve the dust population in the range 3-15 microns, and to study selected emission features, in order to characterize dust size and composition. we will clarify the relationship of dust grains to the gaseous components of both the stellar wind and the stationary circumstellar envelopes. we will use isophot to investigate the properties of the cool dust, and to extend our present knowledge to the completely new spectral range 100 -- 200 micron. we will attempt to understand the mechanism regulating the formation and survival of the dust grains in such a close proximity to these hot stars, thus constraining temperature and density conditions in the inner circumstellar region. this information will complement our extensive studies of circumstellar shells around lbvs, and ofpe/wn9 stars, performed over several years of corono- graphic and spectroscopic ground based and hst observations.
Instrument
CAM01 , PHT03 , PHT22
Temporal Coverage
1996-08-09T17:53:48Z/1997-12-04T05:44:25Z
Version
1.0
Mission Description
The Infrared Space Observatory (ISO) was the world's 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, 1999, Dust Characterization In Circumstellar Shells Around Evolved Comma Massive Stars, 1.0, European Space Agency, https://doi.org/10.5270/esa-kedonmj
