since the beginning of star formation research the main aim has been to find the youngest forming star, thus providing the link between gas condensations and visible stars. yet when looking at observational evidence exhibited by proposed candidates, nature presents us with such a variety of observational phenomena that one can seldom account for all of them. with this proposal we want to address the problem of finding the youngest high mass forming stars and, by comparison with other well studied classes of young stellar objects (ysos), to understand the evolution of the physical conditions of circumstellar matter around massive stars since before the ignition of hydrogen burning. our proposed targets are luminous iras sources believed to be in a phase preceeding the appearance of ultracompact (uc) hii regions; we will use lws in grating mode to observe the emitted spectrum and compare with that of known uc hii regions (in which hydrogen burning has obviously started) as well as with theoretical predictions of line intensities from photoionization regions. all of our proposed sources are deeply embedded within their dust cocoons and to investigate the physical conditions nearest to the central forming objects makes the use of iso mandatory.
Instrument
LWS01
Temporal Coverage
1996-10-04T21:27:00Z/1996-10-19T03:47:58Z
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, Spectroscopy Of Candidate Progenitors Of Ultracompact Hii Regions, 1.0, European Space Agency, https://doi.org/10.5270/esa-m17xpk7
