===================================================================== ==> in this proposal, more time is being requested for afuente.pdr01 ===================================================================== we propose to observe a sample of high excitation molecular lines in two selected positions of the photon-dominated region (pdr) associated with ngc 7023. ngc 7023 is a prototypical reflection nebula (rn), and the already existing single-dish and interferometric ground based observations, show that it is one of the best objects to study the physical and chemical structure of pdrs. most of the projects on pdrs are centered on the pdrs formed at the edges of hii regions. the results found in these pdrs cannot be extrapolated to the pdrs associated with rne. rne are illuminated by intermediate mass stars and the spectrum and intensity of the incident uv field, as well as the gas physical conditions are different. since the birth rate for intermediate mass stars is much larger than for massive o stars, the study of the pdrs associated with them is of major importance for the understanding of the galactic and extragalactic interstellar medium. in the first call for proposals we got time to observe the infrared rotational lines of h2, co, oh, ch, ch2, heh+ and nh3 toward four selected positions. our goal was to estimate the abundances of these molecules, determine the physical conditions of the hot molecular gas, and understand the cooling mechanisms across the pdr. however, the time estimates given by the first lws time estimator happened to be severely wrong, and we can only observe two of them within the time allocated for this project. with only two positions, we are unable to achieve our objectives. therefore, we propose to complete our observations with two positions more.
Instrument
LWS01 , LWS04 , SWS02
Temporal Coverage
1997-04-13T12:52:35Z/1997-09-07T11:11:48Z
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, FUENTE et al., 1998, 'A CHEMICAL STUDY OF THE HOT AND DENSE MOLECULAR GAS ADJACENT TO THE PHOTON-DOMINATED REGION (PDR) ASSOCIATED WITH NGC 7023', 1.0, European Space Agency, https://doi.org/10.5270/esa-df19uk5
