ISO Observations of Pre-Stellar Cores and Young Stellar Objects

Abstract

We summarize the observations of the Infrared Space Observatory (ISO) concerning the earliest stages of the stellar formation. The observations of samples of sources in different evolutionary stages are reviewed, addressing in particular how the physical and chemical properties of the protostellar environments change from the pre-stellar cores to the protostars at the end of their accretion phase. In addition, the mid-IR surveys in nearby star-forming regions are discussed, showing their implications for the understanding of the stellar initial mass function.

Water in star- and planet-forming regions

“…Prior to Herschel the observational perspective of water vapour pointed to some intriguing issues with respect both to its disposition as solid or vapour and to its destruction. ISO found clear evidence for hot water associated with shocks but also perhaps isolated in the hot cores of both low-and high-mass stars (see the reviews of van Dishoeck [4] and Nisini et al [57]). SWAS and Odin discovered that cold water vapour is less abundant than expected from pure gas-phase chemistry, hinting at a role of freeze-out and ice formation [3,76].…”

“…Spitzer with its wavelength coverage and moderate spectral resolution enabled the detection of very hot gas which is found in outflows (Melnick et al, 2008) and also in the innermost regions of protoplanetary disks (Carr & Najita, 2008). ISO was best suited for the detection of warm and hot water in shocks and also in the hot cores around massive stars (van Dishoeck, 2004;Nisini et al, 2005, and references therein). In the case of Spitzer and ISO the lines are generally not velocity resolved.…”

“…Prior to Herschel the observational perspective of water vapor pointed to some intriguing issues with respect both to its disposition as solid or vapor and also its destruction. ISO found clear evidence for hot water associated with shocks but also perhaps isolated in the hot cores of both low and high mass stars (see the review of van Dishoeck, 2004;Nisini et al, 2005). SWAS and Odin discovered that cold water vapor is less abundant than expected from pure gas-phase chemistry, hinting at a role of freeze-out and ice formation (Snell et al, 2000b;Hjalmarson et al, 2003).…”