Astronomy and Astrophysics, volume 306, 267-277 (1996/2-1)
NH3 and HCO+ towards luminous IRAS sources.
SCHREYER K., HENNING T., KOEMPE C. and HARJUNPAEAE P.
Abstract (from CDS):
We have selected 67 objects for observation that are presumably massive young stellar objects. They were from the IRAS Point Source Catalogue based on their infrared flux (Fν≥500Jy at 100µm). All objects have been surveyed in the NH3(1,1) and (2,2) lines, and a subsample of 53 objects in the rotational line of HCO+(J=1-0). 25 objects (37%) were detected in the NH3(1,1) line, 18 objects (27%) in the NH3(2,2) line, and 38 objects (72%) in the HCO+ line. Two objects, IRAS 06058+2138 and IRAS 06061+2151, have been mapped in the two ammonia transitions. From the molecular line data, we have derived the kinetic temperature Tkin and the NH3 column densities. These data were combined with data from the literature and data derived from the IRAS fluxes (dust colour temperature Td, optical depth τ, luminosity). No clear correlations were found; the data are, however, consistent with least square fits found by Wouterloot et al. (1988a). The probability to detect H2O maser sources is strongly correlated with the detection of NH3 emission: Water maser emission has been seen towards 83% of those objects with clear detections of NH3(1,1) and (2,2) lines.
circumstellar matter - ISM: molecules - ISM: individual objects: IRAS 06058+2138 , IRAS 06061+2151 - radio lines: ISM
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