V W A S O F T W A R E

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VWA Stellar Spectrum Software

How do you manage 2000 Angstroms with hundreds of spectra lines? The answer to your problem may be the VWA package.

What can VWA do?

VWA will make an analysis of your normalized stellar spectrum with a certain degree of manual interaction.

How does VWA work?

VWA is designed to do abundance analysis. It consists of three main parts: (1) selection of lines, (2) computation of abundances for these lines (matching the observed and computed spectrum), and (3) checking of the fitted lines.

The VWA software package is written in IDL. Thus, you will also need an IDL licence to run the software.

Download VWA.

The name VWA

The name VWA is the abbreviation of v sin i, wavelength shift, abundance analysis

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NEWS

2007-04-03
Programs and Manual updated for 2007
The yearly update of VWA programs has been completed. The manual has been expanded and now covers the analysis of binary stars.

2006-01-12
VWA joins the VSOP project
The VSOP project collects spectra of interesting variable and peculiar stars. VWA will be used to determine fundamental parameters and abundances in the VSOP targets.

2006-26-01
Programs and Manual updated
The manual was finally updated with much more elaborate instructions on how to install the code on your system. I included descriptions on how to make log-gf correction files. A brief description of how to analyse double-lined binary stars also included. Some of the core VWA programs have been updated.

2006-25-01
Comparison of ATLAS9 / MARCS models
To use MARCS models with VWA you need to change the format of the MARCS atmosphere model files to that of Kurucz ".krz" files. I have made comparisons for the Fe1/Fe2 ionization balance found in a high-resolution and high-S/N spectrum of the Sun when using an interpolated Heiter et al. (2002) model (modified ALTAS9) and a MARCS model (provided by U.J. Graae). The difference between the mean Fe1/Fe2 abundances is 0.14 dex for the modified Kurucz ATLAS9 model but only 0.06 dex for the MARCS model. There is still a significant (positive) correlation of Fe1 abundances and excitation potentials.

2005-17-07
VWA can analyse binary stars
I have expanded VWA to do abundance analysis of binary stars. You need to specify the luminosity ratio (e.g. based on the relative radii and theoretical Planck functions) and
the relative radial velocities of the components. The documentation for working with binary stars has not been written yet.

The figure below is from automatic fitting with VWA: The crosses mark the observed spectrum of the binary WZ Oph from FEROS. The fitted Cu at 5505.5 Angstrom line is marked. The dashed line is the synthetic spectrum of the secondary star and the dash-dotted line is for the primary star. The combined spectrum is the solid line. The flux ratio of the binary is close to 1.0

VWA fit binary (haa2.pro)

2005-18-04
VWA updated
The official installation and user guide is now available. In addition, several minor bug fixes.

2004-14-04
VWA is available for download
After three years of development an interactive version of VWA is available.