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Ammonia in C-rich stars

Published online by Cambridge University Press:  30 December 2019

Bartosz Etmański ,
Mirosław R. Schmidt ,
Bosco H. K. Yung  and
Ryszard Szczerba
Bartosz Etmański
Affiliation:
Nicolaus Copernicus Astronomical Centre of the Polish Academy of Sciences, Departament of Astrophysics, 87-140 Toruń, Rabiańska 8, Poland
Mirosław R. Schmidt
Affiliation:
Nicolaus Copernicus Astronomical Centre of the Polish Academy of Sciences, Departament of Astrophysics, 87-140 Toruń, Rabiańska 8, Poland
Bosco H. K. Yung
Affiliation:
Nicolaus Copernicus Astronomical Centre of the Polish Academy of Sciences, Departament of Astrophysics, 87-140 Toruń, Rabiańska 8, Poland
Ryszard Szczerba
Affiliation:
Nicolaus Copernicus Astronomical Centre of the Polish Academy of Sciences, Departament of Astrophysics, 87-140 Toruń, Rabiańska 8, Poland
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Abstract

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HIFI instrument onboard the Herschel satellite provided an unprecedented number of detections of rotational transitions of ammonia in circumstellar envelopes of evolved stars including massive red supergiants, Asymptotic Giant Branch (AGB), and post-AGB stars. The chemistry of ammonia formation in the circumstellar envelopes of evolved stars is poorly understood. The mechanisms proposed for its formation are processes behind the shock front, photochemistry in the inner part of the clumpy envelope, and formation on dust grains. We present results of the non-local thermodynamical equilibrium (non-LTE) radiative transfer modeling of ammonia transitions, mainly of the ground-state rotational one NH3 JK = 10 – 00 at 572.5 GHz, in selected AGB stars, aiming at the quantitative estimation of the NH3 abundance. The model of ammonia includes IR radiative pumping via v2 = 1 vibrational band at 10 μm.

Keywords

line: profilessubmilimeter: starsstars: AGB and post-AGBcircumstellar matter
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 14 , Symposium S343: Why Galaxies Care About AGB Stars: A Continuing Challenge through Cosmic Time , August 2018 , pp. 396 - 397
Copyright
© International Astronomical Union 2019 

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