J/A+A/625/A78 Carbon and nitrogen rate coefficients (Amarsi+, 2019)
Excitation and charge transfer in low-energy hydrogen atom collisions with
neutral carbon and nitrogen.
Amarsi A.M., Barklem P.S.
<Astron. Astrophys. 625, A78 (2019)>
=2019A&A...625A..78A 2019A&A...625A..78A (SIMBAD/NED BibCode)
ADC_Keywords: Atomic physics
Keywords: atomic data - atomic processes - line: formation -
radiative transfer - stars: abundances
Abstract:
Low-energy inelastic collisions with neutral hydrogen atoms are
important processes in stellar atmospheres, and a persistent source of
uncertainty in non-LTE modelling of stellar spectra. We calculate and
study excitation and charge transfer of CI and of NI due to such
collisions. We use a previously presented method that is based on an
asymptotic two-electron linear combination of atomic orbitals (LCAO)
model of ionic-covalent interactions for the adiabatic potential
energies, combined with the multichannel Landau- Zener model for the
collision dynamics. We find that charge transfer processes typically
lead to much larger rate coefficients than excitation processes,
consistent with studies of other atomic species. Two-electron
processes were considered and lead to non-zero rate coefficients that
can potentially impact statistical equilibrium calculations. However,
they were included in the model in an approximate way, via an estimate
for the two-electron coupling that was presented earlier in the
literature: the validity of these data should be checked in a future
work.
Description:
c-state.dat contains information about the carbon states
n-state.dat contains information about the nitrogen states
c-rate.dat contains the rate coefficients for carbon
n-rate.dat contains the rate coefficients for nitrogen
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
c-state.dat 44 38 Carbon states
n-state.dat 44 33 Nitrogen states
c-rate.dat 29 28880 Rate coefficients for carbon
n-rate.dat 29 21780 Rate coefficients for nitrogen
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See also:
J/A+A/622/L4 : Carbon and oxygen in metal-poor halo stars (Amarsi+, 2019)
Byte-by-byte Description of file: c-state.dat n-state.dat
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Bytes Format Units Label Explanations
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1- 3 I03 --- i State index
7- 16 A10 --- Label State configuration and term
20- 30 F11.8 eV EA C atomic/ionic level energy
34- 44 F11.8 eV Ecov ? CH state energy
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Byte-by-byte Description of file: c-rate.dat n-rate.dat
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Bytes Format Units Label Explanations
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1- 3 I03 --- i1 Initial state index
7- 9 I03 --- i2 Final state index
13- 17 I05 K T Temperature
21- 29 E9.3 cm3/s q Rate coefficient
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Acknowledgements:
Anish Mayur Amarsi, amarsi(at)mpia.de
(End) Patricia Vannier [CDS] 10-Apr-2019