Query : 2015A&A...578A..65Y

2015A&A...578A..65Y - Astronomy and Astrophysics, volume 578A, 65-65 (2015/6-1)

Collisional quenching of highly rotationally excited HF.


Abstract (from CDS):

Collisional excitation rate coefficients play an important role in the dynamics of energy transfer in the interstellar medium. In particular, accurate rotational excitation rates are needed to interpret microwave and infrared observations of the interstellar gas for nonlocal thermodynamic equilibrium line formation. Theoretical cross sections and rate coefficients for collisional deexcitation of rotationally excited HF in the vibrational ground state are reported. The quantum-mechanical close-coupling approach implemented in the nonreactive scattering code MOLSCAT was applied in the cross section and rate coefficient calculations on an accurate 2D HF-He potential energy surface. Estimates of rate coefficients for H and H2 colliders were obtained from the HF-He collisional data with a reduced-potential scaling approach. The calculation of state-to-state rotational quenching cross sections for HF due to He with initial rotational levels up to j=20 were performed for kinetic energies from 10–5 to 15000cm–1. State-to-state rate coefficients for temperatures between 0.1 and 3000 K are also presented. The comparison of the present results with previous work for lowly-excited rotational levels reveals significant differences. In estimating HF-H2 rate coefficients, the reduced-potential method is found to be more reliable than the standard reduced-mass approach. The current state-to-state rate coefficient calculations are the most comprehensive to date for HF-He collisions. We attribute the differences between previously reported data and our results to differences in the adopted interaction potential energy surfaces. The new He rate coefficients can be used in a variety of applications. The estimated H2 and H collision rates can also augment the smaller datasets previously developed for H2 and electrons.

Abstract Copyright:

Journal keyword(s): molecular processes - molecular data - ISM: molecules

VizieR on-line data: <Available at CDS (J/A+A/578/A65): aa_hehf.dat>

Simbad objects: 5

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Number of rows : 5
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 NGC 253 SyG 00 47 33.134 -25 17 19.68   8.03   6.94 8.1 ~ 3261 2
2 NAME Orion-KL SFR 05 35 14.16 -05 22 21.5           ~ 2251 1
3 NAME Orion Bright Bar reg 05 35 22.30 -05 24 33.0           ~ 841 0
4 IRC +10216 C* 09 47 57.40632 +13 16 43.5648           C9,5e 2304 0
5 NGC 4945 Sy2 13 05 27.279 -49 28 04.44   9.31 14.40 7.55   ~ 1436 2

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