PoWR - The Potsdam Wolf-Rayet Models
This WEB interface allows to inspect and download synthetic spectra for
Wolf-Rayet stars. The spectra are calculated from PoWR model atmospheres
which account for Non-LTE, spherical expansion and metal line
blanketing. The models are described in
Gräfener G., Koesterke L., Hamann W.-R.: 2002, Astron. Astrophys.,
387, 244 and
Hamann, W.-R., Gräfener: 2003, Astron. Astrophysics, 410, 993.
The WN model grids presented via this WEB interface belong to the
publication
Hamann, W.-R., Gräfener: 2004, Astron. Astrophysics, 427, 697,
where more details can be found. We expect that users of the PoWR
spectra will give references to these papers.
Note that this homepage makes use of popup windows; a popup blocker
prevents its proper operation.
In case of problems please contact Wolf-Rainer Hamann
(wrh@astro.physik.uni-potsdam.de).
This WEB interface has been developed by Daniel M. Hamann and
Wolf-Rainer Hamann (2004).
Synthetic spectra
The following data are available for each model:
- Spectral Energy Distribution
(emergent flux received at 10pc distance, low spectral resolution)
- Line spectrum in high resolution for different wavelength bands
(optionally normalized or flux-calibrated)
Model parameters and organisation
The models are arranged in different Model Grids.
Each model grid is characterized by a set of common parameters, such as
stellar luminosity, terminal wind velocity, clumping contrast, and
chemical composition. The following grids are available yet:
| Grid | WNE | WNL | WC |
| log L / Lsun | 5.3 | 5.3 | 5.3 |
| vfinal [km/s] | 1600 | 1000 | 2000 |
| clumping D | 4 | 4 | 10 |
| Mass fraction | | |
|
| H | 0 | 0.2 | 0 |
| He | 0.98 | 0.78 | 0.55 |
| C | 1E-4 | 1E-4 | 0.4 |
| N | 0.015 | 0.015 | 0 |
| 0 | 0 | 0 | 0.05 |
| Fe | 0.0014 | 0.0014 | 0.0016 |
Each grid has a two-dimensional parameter space, namely the stellar
temperature T* and the "transformed radius" Rt. The
latter is a function of the mass-loss rate and the stellar radius.
Thanks to an approximate scaling invariance of WR
atmospheres, the same model spectrum can be applied to stars with
different luminosities, but same T* and Rt. When
doing so, the absolute fluxes must be scaled proportional to L, the
radius R* proportional to L1/2, and the mass-loss
rate proportional to L3/4.