TL;DR
proEQUIB is an IDL library that provides tools for plasma diagnostics and chemical abundance analysis in gaseous nebulae, facilitating studies of their physical conditions and interstellar extinction.
Contribution
It introduces a comprehensive IDL library with API functions for plasma diagnostics and abundance analysis, compatible with GDL, supporting spatially-resolved nebular studies.
Findings
Enables determination of physical conditions from emission lines
Allows derivation of chemical abundances and interstellar extinction
Supports analysis of nebular spectra using API functions
Abstract
The emission lines emitted from gaseous nebulae carry valuable information about the physical conditions and chemical abundances of ionized gases in these objects, as well as the interstellar extinction. "proEQUIB" is a library containing several application programming interface (API) functions developed in the Interactive Data Language (IDL), which can be used for plasma diagnostics and abundance analysis of nebular spectra. This IDL library can also be used by the GNU Data Language (GDL), which is a free and open-source IDL compiler. This package includes several API functions to determine physical conditions and chemical abundances from collisionally excited lines (CEL) and recombination lines (RL), derive interstellar extinctions from Balmer lines, and deredden the observed fluxes. This IDL library heavily relies on the IDL Astronomy User's library and the IDL "AtomNeb" library.…
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proEQUIB: IDL Library for Plasma Diagnostics and Abundance Analysis
Ashkbiz Danehkar
Research Centre in Astronomy, Astrophysics and Astrophotonics, Macquarie University, Sydney, NSW 2109, Australia
Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
††margin:
DOI: 10.21105/joss.00899
Software
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**Submitted: 30 June 2018
Published: 04 December 2018**
**License
Authors of papers retain copyright and release the work under a Creative Commons Attribution 4.0 International License (CC-BY).**
Summary
The emission lines emitted from gaseous nebulae carry valuable information about the physical conditions and chemical abundances of ionized gases in these objects, as well as the interstellar reddening. We determine the electron temperature, the electron density, and the ionic abundances from the dereddened fluxes of collisionally excited lines (CEL) and recombination lines (RL) identified in nebular spectra (see e.g. Danehkar, Parker, and Ercolano (2013); Danehkar et al. (2014); Danehkar, Parker, and Steffen (2016); Danehkar (2018b)).
proEQUIB is a library including several application programming interface (API) functions developed in the Interactive Data Language (IDL), which can be used to determine temperatures, densities, and chemical abundances from emission lines of ionized nebulae. This IDL library can also be used by the GNU Data Language (GDL) (Arabas et al. (2010); Coulais et al. (2010)), which is a free and open-source alternative IDL compiler. This IDL/GDL package employs the IDL library AtomNeb Atomic Data for Ionized Nebulae (Danehkar (2018a)), which contains collision strengths and transition probabilities for collisional excitation calculations, and recombination coefficients for recombination calculations. This package includes several API functions to determine physical conditions and chemical abundances from CEL and RL, derive interstellar extinctions from Balmer lines, and deredden the observed fluxes:
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The API functions for the CEL analysis were developed in the IDL programming language based on the algorithm of the FORTRAN program EQUIB (Howarth and Adams (1981); Howarth et al. (2016)), which calculates atomic level populations and line emissivities in statistical equilibrium in multi-level atoms for the given physical conditions. These API functions can be used to determine the electron temperature, the electron density, and the ionic abundances from the dereddened fluxes of collisionally excited lines emitted from ionized gaseous nebulae.
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The API functions for the RL analysis were developed in IDL according to the algorithm of the recombination scripts by X. W. Liu and Y. Zhang included in the FORTRAN program MOCASSIN (Ercolano et al. (2003); Ercolano, Barlow, and Storey (2005)). These API functions can be used to determine the ionic abundances from the dereddened fluxes of recombination lines emitted from ionized nebulae.
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The API functions for the reddening analysis were developed based on the methods of the reddening functions from the Space Telescope Science Data Analysis System (STSDAS) IRAF Package (Bushouse and Simon (1994); Shaw and Dufour (1994)). These API functions can be employed to obtain interstellar extinctions for different reddening laws from the observed fluxes of Balmer lines detected in nebular spectra, and deredden the measured fluxes of emission lines.
proEQUIB has recently been used for plasma diagnostics and abundance analysis of some planetary nebulae (Danehkar, Parker, and Steffen (2016); Danehkar (2018b)). This IDL/GDL package heavily relies on the IDL Astronomy User’s library (Landsman (1993); Landsman (1995)) and the IDL library AtomNeb (Danehkar (2018a)). The API functions of this IDL library can easily be utilized to generate spatially-resolved maps of extinction, temperature, density, and chemical abundances from integral field spectroscopic observations (see e.g. Danehkar, Parker, and Ercolano (2013); Danehkar et al. (2014); Danehkar (2014)).
Acknowledgements
A.D. acknowledges the receipt of a Macquarie University Research Excellence Scholarship.
References
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