VI/150Recombination coefficients for O II lines - SSB2 (Storey+, 2017)

Recombination coefficients for O II lines in nebular conditions. Storey P.J., Sochi T., Bastin R. <Mon. Not. R. Astron. Soc., 470, 379-389> =2017MNRAS.470..379S =2017yCat.6150....0SADC_Keywords: Atomic physicsKeywords: atomic data - atomic processes - radiation mechanisms - planetary nebulae - H II regions - astrochemistry - plasmas - numerical methods - oxygen - recombination lines - emission coefficients - recombination coefficientsAbstract: We present the results of a calculation of recombination coefficientscients for O^2 +^{+e}-^ using an intermediate coupling treatment that fully accounts for the dependence of the distribution of population among the ground levels of O^{2+}on electron density and temperature. The calculation is extended down to low electron temperatures where dielectronic recombination arising from Rydberg states converging on the O^{2+}ground levels is an important process. The data, which consist of emission coefficientscients for 8889 recombination lines and recombination coefficientscients for the ground and metastable states of O^{+}are in Cases A, B and C, and are organised as a function of the electron temperature and number density, as well as wavelength. An interactive fortran 77 data server is also provided as an accessory for mining the line emission coefficients and obtaining Lagrange interpolated values for any choice of the two variables between the explicitly provided values for any set of wavelengths. Some illustrations of the application of the new data to nebular observations are also provided.Description: The list presents emission and recombination coefficients of the O II transitions arising from recombination of doubly-ionised oxygen O^{2+}with a free electron. An intermediate coupling treatment that fully accounts for the dependence of the distribution of population among the ground levels of O^{2+}on electron temperature (Te) and electron number density (Ne) is used. The calculation is extended down to low electron temperatures where dielectronic recombination arising from Rydberg states converging on the O^{2+}ground levels is an important process. The data are given as function of Te and Ne in three Cases (A, B and C). The data are suitable in particular for the physical conditions found in planetary nebulae and HII regions. An interactive data server in the form of fortran 77 code is also provided as an accessory for mining the data of emission coefficients and obtaining Lagrange interpolated values for any choice of the two variables, Te and Ne, between the explicitly provided values for any set of wavelengths and for any Case.File Summary:

FileName Lrecl Records Explanations

ReadMe 80 . This file list.dat 30 3 List of repertories DataFiles/* 0 2 Files for OII data DataServer/* 0 1 fortran 77 code Examples/* 0 4 Examples

See also: VI/141 : Computed List of Collision Strengths for nebular [OIII] Optical and Infrared Lines - SSB (Storey+, 2014) VI/144 : Computed List of Effective Collision Strengths for nebular [OIII] - SS3 (Storey+, 2015)Byte-by-byte Description of file: list.dat

Bytes Format Units Label Explanations

1- 10 A10 --- Rep Repertory name 13- 30 A18 --- Content Content of the directory

Description of the data files (DataFiles/*): The data are contained in 2 files that we describe in the following bullet points: 1. Data file named "OIIlines_ABC": this file consists of two main sections preceded by a short header which consists of a general description of the file structure and the abbreviations used to label and explain the data blocks and their units. The structure of these sections is as follows: a. The first section consists of 8889 indexed text lines corresponding to the provided 8889 OII transitions where each text line contains full identification of the corresponding transition by its upper and lower level as well as its wavelength and other relevant atomic designations. b. The second section consists of 8889 parts where each part corresponds to one transition as indexed above. Each part is made of three blocks where each block corresponds to one of the three Cases. Each one of these blocks is a rectangular array of emission coefficients of the indexed transition arranged in 25 rows, as a function of log_{10}(Te) between 2.0-4.4 in steps of 0.1, and 16 columns as a function of log_{10}(Ne) between 2.0-5.0 in steps of 0.2. 2. Data file named "OIImeta_ABC": this file contains the recombination coefficients to the ground and meta-stable levels of O^{+}as functions of Te and Ne and Case (A, B and C). The file contains 14 data blocks which are described in the following: a. A block for the effective recombination coefficients of the ground level 2s^{2}2p^{3}^{4S}o_{3/2}in Case A. b. Four blocks for the effective recombination coefficients of the two levels 2s^{2}2p^{3}^{2}D^{o}_{5/2}and^{2}D^{o}_{3/2}each in Case A and B. c. Six blocks for the effective recombination coefficients of the two levels 2s^{2}2p^{3}^{2}P^{o}_{3/2}and^{2}P^{o}_{1/2}each in Case A, B and C. d. Three blocks for the total recombination coefficients, one block for each Case. Each one of the 14 data blocks is structured as a function of Te and Ne in log_{10}identical to the structure of the emission coefficient blocks in the "OIIlines_ABC" file, as described above. Note: the units of the provided data are as follows: (a) Te: K (b) Ne: cm^{-3}(c) Emission coefficients: erg.cm^3/s per O^{2+}ion per electron (d) Recombination coefficients: cm^3/s per O^{2+}ion per electron (e) Wavelengths: AngstroemDescription of the data server (DataServer/*): The data server is a fortran 77 code named "exlines.f" designed to excavate the emission coefficient data in the "OIIlines_ABC" file in interactive mode by offering branching selections for the user. The size of the recombination coefficient data in the "OIImeta_ABC" file is very small. Moreover, the main intended use of these data is in modelling and hence there is no compelling need for interpolation. Therefore, no accessory for mining and interpolating these data was provided. The data server reads the "OIIlines_ABC" file and provides easy access to the lines and their emission coefficients at the desired Te and Ne values for a given selection of wavelength and Case. When the required data are within the above-stated Te and Ne ranges but are not at the grid points of Te and Ne as described above, a 6-point Lagrange interpolation in Te and Ne is used to provide the desired data. There are two main options offered by the data server: generating a line list and extracting emission coefficients for a user supplied list of lines in user specified conditions. These options are explained in the following bullet points: (1) Generating a line list where the server offers two choices: (1a) Listing all the 8889 lines. (1b) Specifying a wavelength range for the list of lines desired by the user. In each one of these choices, two files are generated that contain the list of lines where the lines in one of these files (named "OIIdata_{list}eorder") are ordered in decreasing order of emission coefficient and in the other file (named "OIIdata_{list}worder") in increasing order of wavelength. The full list in the latter file is preceded by a list of only the strongest lines in the required wavelength range. The emission coefficients in these files correspond to typical nebular conditions of Te=10000 and Ne=10000. (2) Extracting emission coefficients where the user is asked to supply a list of lines in a text file (OIIdata_xxxx) for which the data are required. The user then has the choice between: (2a) Providing a list of T_{e-N}e pairs in a file (TDpairs_xxxx) for which the data are needed. The first entry in the file TDpairs_xxxx is the number of pairs followed by the pairs each in a row. (2b) Providing a range of log_{10}(Te) and log_{10}(Ne) in a file (TDranges_xxxx) defining a one- or two-dimensional grid for which the data are required. The file TDranges_xxxx contains 3 rows. The first row contains the number of T_e and N_e points. The second row contains the first value of log_{10}(Te) in the grid followed by the step size. The third row is the same as the second row with regard to log_{10}(Ne). In all of these 4 choices (i.e. 1a, 1b, 2a and 2b) the user has the option to have the data for Case A, B or C. The distributed data bundle contains 4 examples (one for each choice) with the input and output data files as well as the screen output to demonstrate the use of the data server.Acknowledgements: P.J. Storey: University College London, pjs(at)star.ucl.ac.uk Taha Sochi: University College London, t.sochi(at)ucl.ac.uk Robert Bastin: Surbiton High School(End)Taha Sochi [University College London], Patricia Vannier [CDS] 11-May-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