Astronomy and Astrophysics – Astrophysics
Scientific paper
2002-12-10
Astron.Astrophys. 398 (2003) 1049-1062
Astronomy and Astrophysics
Astrophysics
16 pages, 13 figures, Astronomy and Astrophysics, in press
Scientific paper
10.1051/0004-6361:20021705
We have investigated whether the nu_4 feature of NH4+ is a viable candidate for the 6.85 micron absorption band seen towards embedded young stellar objects. To produce NH4+ astrophysical ice analogs consisting of H2O, CO2, NH3 and O2 were UV photolysed. The IR spectra reveal peaks that are identified with the NH4+, NO2-, NO3- and HCO3- ions. It is shown that the NH4+ matches two absorption features that are observed towards embedded young stellar objects, i.e., the strong 6.85 micron feature and the 3.26 micron feature. The characteristic redshift with temperature of the interstellar 6.85 micron feature is well reproduced. The abundance of NH4+ in interstellar ices would be typically 10 % relative to H2O. The experiments show that the counterions produce little distinct spectral signature but rather a pseudo-continuum if a variety of them is present in a H2O dominated environment. The anions could therefore go undetected in IR spectra of interstellar ice. In the ISM, where additional mechanisms such as surface chemistry and additional elements such as sulfur are available many acids and an even wider variety of anions could be produced. These components may be detectable once the ices sublime, e.g, in hot cores.
Khanna Raj K.
Schutte Willem A.
No associations
LandOfFree
Origin of the 6.85 micron band near young stellar objects: The ammonium ion (NH4+) revisited does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Origin of the 6.85 micron band near young stellar objects: The ammonium ion (NH4+) revisited, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Origin of the 6.85 micron band near young stellar objects: The ammonium ion (NH4+) revisited will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-74491