Abstract
This paper presents the richness of submillimeter spectral features in the high-mass star forming region AFGL 2591. As part of the CHESS (Chemical Herschel Survey of Star Forming Regions) Key Programme, AFGL 2591 was observed by the Herschel/HIFI instrument. The spectral survey covered a frequency range from 480 up to 1240 GHz as well as single lines from 1267 to 1901 GHz (i.e. CO, HCl, NH3, OH and [CII]). Rotational and population diagram methods were used to calculate column densities, excitation temperatures and the emission extents of the observed molecules associated with AFGL 2591. The analysis was supplemented with several lines from ground-based JCMT spectra. From the HIFI spectral survey analysis a total of 32 species were identified (including isotopologues). In spite of the fact that lines are mostly quite week, 268 emission and 16 absorption lines were found (excluding blends). Molecular column densities range from 6e11 to 1e19 cm-2 and excitation temperatures range from 19 to 175 K. One can distinguish cold (e.g. HCN, H2S, NH3 with temperatures below 70 K) and warm species (e.g. CH3OH, SO2) in the protostellar envelope.
Highlights
Massive stars play a major role in the evolution of galaxies
Among the several key projects devoted to those studies, we focus here on the Herschel key program Chemical Herschel Survey of Star Forming Regions (CHESS, Ceccarelli et al 2010)
The corresponding bands are 5b, 6a (CO), 6b (CO), 7a (NH3, CO) and 7b (CO, OH, [CII]). This is the second in a series of papers based on HIFI/CHESS data of AFGL 2591 and a detailed description of its data reduction process has been provided in Paper I (Van der Wiel et al 2013), basic information is recalled here as well
Summary
Massive stars play a major role in the evolution of galaxies. From their birth in dense molecular clouds to their death as a supernova explosion, massive stars interact heavily with their surroundings by emitting strong stellar winds and by creating heavy elements (Zinnecker & Yorke 2007). Among the several key projects devoted to those studies, we focus here on the Herschel key program Chemical Herschel Survey of Star Forming Regions (CHESS, Ceccarelli et al 2010). Spectral surveys simultaneously cover a wide variety of molecular and atomic lines In this way they offer the possibility to probe cold and warm gas and the fundamental processes that occur in star forming regions. AFGL 2591 is one of the CHESS sources It is a relatively isolated high-mass protostellar object with a bipolar molecular outflow (Van der Tak et al 1999). The richness of the detected lines in AFGL 2591 from the HIFI/CHESS spectral survey gives us the opportunity to gain detailed insight into its chemical and physical structure. Appendix A gives a table with all detected transitions and plots of their line profiles
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