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A&A Supplement series, Vol. 121, February 1997, 255-274

Received February 14; accepted May 20, 1996

Ammonia observations towards molecular and optical outflows

G. Angladatex2html_wrap3027 - I. Sepúlvedatex2html_wrap3029 - J.F. Gómeztex2html_wrap3031

Send offprint request: G. Anglada

tex2html_wrap3033  Departament d'Astronomia i Meteorologia, Universitat de Barcelona, Av. Diagonal 647, E-08028 Barcelona, Spain
tex2html_wrap3035  Instituto de Astronomía, UNAM, Apdo. Postal 70-264, 04510 México DF, Mexico
tex2html_wrap3037  Laboratorio de Astrofísica Espacial y Física Fundamental, INTA, Apdo. Correos 50727, E-28080 Madrid, Spain
tex2html_wrap3039  Instituto de Astrofísica de Andalucía, CSIC, Apdo. Correos 3004, C/ Sancho Panza s/n, E-18080 Granada, Spain


We observed the (J,K) = (1,1) and (J,K) = (2,2) inversion transitions of the tex2html_wrap_inline2995 molecule towards several regions with molecular or optical outflows: RNO 43, HH 83, HH 84, HH 86/87/88, L1641-N, L100, L483, L673, IRAS 20188+3928, L1228, L1048, HHL 73, L1251 (IRAS 22343+7501 and IRAS 22376+7455) and L1262, using the 37 m radio telescope of the Haystack Observatory. Additionally, we searched for the tex2html_wrap_inline2999 tex2html_wrap_inline3001\ maser line towards nine regions, detecting a weak tex2html_wrap_inline3003 maser near IRAS 20188+3928. We detected and mapped tex2html_wrap_inline3005 emission in 14 of the 15 regions observed, and we estimated physical parameters for the high density gas. We systematically found that the position of the best candidate for the outflow excitation in each region is very close to an tex2html_wrap_inline3007 emission peak. From a statistical study of the data presented in this paper, together with previously published data, we conclude that the tex2html_wrap_inline3009 line emission is more intense towards molecular outflow sources than towards sources with only optical outflows. Therefore, molecular outflows appear to be associated with larger amounts of high density gas. This result suggests a possible evolutive scheme in which young objects associated with molecular outflows lose progressively their neighboring high-density gas, weakening both the tex2html_wrap_inline3011 emission and the molecular outflow in the process, and making optical jets more easily detectable as the total amount of gas decreases.

keywords: ISM: jets and outflows -- ISM: molecules -- masers -- stars: formation

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