Centrum Astronomii
Uniwersytet Mikołaja Kopernika

Observations of the circumstellar ammonia in carbon-rich AGB stars by Herschel/HIFI instument.

dr. M.R. Schmidt, CAMK PAN, Toruń

Ammonia has been found to exists in circumstellar envelopes of evolved stars in amounts that exceed predictons of the current chemical models for both O-rich and C-rich AGB stars. HIFI instrument clearly detected the ground-state rotational transition NH3 J(K)=1,0-0,0 at 572.5 GHz in envelopes of six C-rich AGB stars, including earlier detection in IRC+10216, and nine transitions between the lowest rotational levels in IRC+10216. We present results of the non-LTE radiative transfer modelling conducted with the goal to derive NH3 abundances in these sources. The model of ammonia includes IR radiative pumping via v2=1 vibrational band at 10 micormeter. Theoretical predictions of the model are applied for the analysis of excited rotational ammonia lines available for some of the sources, in particular for IRC+10216.

20.01.2014 - 11:15
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