Access to Astronomical Catalogues

← Click to display the menu
J/A+A/605/A95  CH4 and hot methane continuum hybrid line list (Yurchenko+, 2017)

A hybrid line list for CH4 and hot methane continuum. Yurchenko S.N., Amundsen D.S., Tennyson J., Waldmann I.P. <Astron. Astrophys. 605, A95 (2017)> =2017A&A...605A..95Y (SIMBAD/NED BibCode)
ADC_Keywords: Atomic physics Keywords: molecular data - opacity - infrared: stars - infrared: planetary systems - line: profiles - methods: numerical Abstract: A line list for methane (CH4) is constructed as a combination of 17 million strong absorption lines relative to the reference absorption spectra and a background methane continuum in two temperature-dependent forms of cross sections and super-lines. This approach significantly eases the use of large high temperature line lists as the computationally expensive calculation of pressure-dependent profiles (e.g. Voigt) only need to be performed for a relatively small number of lines. Both the line list and cross sections were generated using a new 34 billion methane line list (known as 34to10), which extends the 10to10 line list to higher temperatures (up to 2000K). The new hybrid scheme can be applied to any large line lists containing billions of transitions. We recommend using super-lines generated on a high resolution grid based on a resolving power of R=1000000 to model the molecular continuum as a more flexible alternative to the temperature-dependent cross sections. Description: The states file ch4_e50.dat contains a list of rovibrational states. Each state is labelled with: nine normal mode vibrational quantum numbers and the vibrational symmetry; three rotational quantum numbers including the total angular momentum J and rotational symmetry; the total symmetry quantum number Gamma and the running number in the same (J,Gamma) block. In addition there are nine local mode vibrational numbers and the largest coefficient used to assign the state in question. Each rovibrational state has a unique number, which is the number of the row in which it appears in the file. This number is the means by which the state is related to the second part of the data system, the transitions files. The total degeneracy is also given to facilitate the intensity calculations. Because of their size, the transitions are listed in 120 separate files, each containing all the transitions in a 100cm-1 frequency range. These transition files t_*.dat contain the strong methane lines lines consisting of three columns: the reference number in the energy file of the upper state, that of the lower state, the Einstein A coefficient of the transition and the transition wavenumber. These entries are ordered by increasing frequency. The name of the file includes the lowest frequency in the range; thus the t-00500.dat file contains all the transitions in the frequency range 500-600cm-1. 19 histograms x_YYYYK.dat files contain CH4 super-lines representing the continuum computed at the temperature T=YYYYK using R=1000000 (7090081 super-lines each) covering the wavenumber range from 10 to 12000cm-1. The energy file, the transitions files and the histograms files are bzipped, and need to be extracted before use. The pressure broadening parameters used in the calculations are listed in broad.dat. A programme ExoCross to generate synthetic spectra from these line lists can be obtained at File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file ch4_e50.dat 163 8194057 Labelled rovibrational states broad.dat 29 31 Line broadening parameters gamma0 and n0 defining the Voigt profile trans/* 36 120 *Transition files (Einstein coefficients) divided into 100cm-1 frequency pieces. hist/* 34 20 A set of CH4 super-lines representing methane continuum at different (T=YYYYK) temperatures (x_YYYYK.dat)
Note on trans/* : The transitions are sorted according with wavenumber. t-xxxxx.dat where xxxxx indicates the lower wavenumber bound.
See also: J/ApJ/757/46 : Hot methane (CH4) line list (Hargreaves+, 2012) J/MNRAS/440/1649 : ExoMol line lists for CH4 (Yurchenko+, 2014) Byte-by-byte Description of file: ch4_e50.dat
Bytes Format Units Label Explanations
1- 12 I12 --- i State ID, non-negative integer index starting at 1 14- 25 F12.6 cm-1 E State energy term value in cm-1 27- 32 I6 --- g Total state degeneracy 39- 40 I2 --- J [0/50] J-quantum number J is the total angular momentum excluding nuclear spin 45 I1 --- G [1/5] Total symmetry in Td(M), Gamma = A1, A2, E, F1, F2 50- 51 I2 --- n1 [0/10] A1-symmetry normal mode quantum number (QN) 54- 55 I2 --- n2 [0/20] E-symmetry normal mode QN 58- 59 I2 --- L2 [0/20] L2 vibrational angular momentum QN 62- 63 I2 --- n3 [0/10] F1-symmetry normal mode QN 66- 67 I2 --- L3 [0/10] L3 vibrational angular momentum QN 70- 71 I2 --- M3 [0/10] M3 Multiplicity index QN 74- 75 I2 --- n4 [0/20] F2-symmetry normal mode QN 78- 79 I2 --- L4 [0/20] L4 vibrational angular momentum QN 82- 83 I2 --- M4 [0/20] M4 Multiplicity index QN 88 I1 --- Gv [1/5] Td(M) vibrational symmetry {GAMMA}(v) (local mode) 94- 95 I2 --- J2 [0/50] Total angular momentum quantum number Same column as J 98- 99 I2 --- K [0/50] Projection of J on axis of molecular symmetry 103 I1 --- Pr [0/1] Rotational parity tau(rot) 107 I1 --- Grot [1/5] Td(M) rotational symmetry {GAMMA}(rot) 111-117 I7 --- NBl [1/9997054] Reference number in the block 121-124 F4.2 --- C2 [0.0/1.00] Square of the largest coefficient 130-131 I2 --- v1 [0/10] Local mode vibrational quantum number 134-135 I2 --- v2 [0/10] Local mode vibrational QN 138-139 I2 --- v3 [0/10] Local mode vibrational QN 142-143 I2 --- v4 [0/10] Local mode vibrational QN 146-147 I2 --- v5 [0/20] Local mode vibrational QN 150-151 I2 --- v6 [0/20] Local mode vibrational QN 154-155 I2 --- v7 [0/20] Local mode vibrational QN 158-159 I2 --- v8 [0/20] Local mode vibrational QN 162-163 I2 --- v9 [0/20] Local mode vibrational QN
Byte-by-byte Description of file: broad.dat
Bytes Format Units Label Explanations
1- 2 A2 --- Type a0-type, see definition in Tennyson, 2016, J. Mol. Spectrosc., 327, 73 4- 10 F7.3 cm-1 gamma0 Voigt gamma parameter (CH4) 12- 20 F9.3 --- n Temperature exponent (CH4) 22- 29 I8 --- J" Lower state rotational quantum number J"
Byte-by-byte Description of file: trans/*
Bytes Format Units Label Explanations
1- 12 I12 --- i" Upper state ID 14- 25 I12 --- i' Lower state ID 27- 36 E10.4 s-1 A Einstein A-coefficient of the transition
Byte-by-byte Description of file: hist/*
Bytes Format Units Label Explanations
1- 17 E17.8 cm-1 nu Frequency wavenumber 19- 34 E16.8 cm/mol I(T) Absorption coefficient at T=YYYYK (in cm/molecule)
Acknowledgements: S.N. Yurchenko, s.yurchenko(at) J. Tennyson, j.tennyson(at)
(End) Patricia Vannier [CDS] 10-Jul-2017
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

catalogue service

© Unistra/CNRS