The project

We propose to use as large a network of optical spectrographs and photometric devices worldwide as possible. We want to secure continuous coverage (i.e. repeated observations several times each clear night at each of many sites):

For spectroscopic variability of mainly the

  • HeII 5411A line in WR134 and the CIII 5696A line in WR135 and WR 137. These lines are nicely isolated in their spectra and are known to show strong, clear variations during previous campaigns, which were never as long or as intense as we propose here.

  • Other lines occurring in the spectra (e.g. HeI 5876 in each star) should also be examined for variability: lines of different ionization are formed at different radial distances in the wind.

Analysis of these spectral variations will allow us to determine reliable statistical properties of the clumps, in search of expected power-law turbulent cascading, while also revealing any other trends, coherent or not. It will also allow us to verify the stability of CIRs during many rotations. It is best to keep the same grating setup (for a given telescope) for each star during the whole run. Echelle spectrographs are highly interesting for us. We could examine many different spectral lines simultaneously at high spectral resolution with Echelles.

Spectroscopic requirements:

  • Resolution should be no worse than 1 Å, i.e. normally 0.3-0.5 Å/pixel dispersion.

  • Signal-to-noise S/N should be no worse than 200.

  • Exposure times for one complete observation should be no longer than 1 hour for each star.

A telluric standard star nearby in the sky should also be observed occasionally in order to be able to subtract out these nuisance terrestrial atmospheric features in the stellar spectra. We also need observations of a star with a relatively flat spectrum (like a sub-dwarf or other) to correct for any instrumental effect (if possible for a given observer).

Parallel photometric broadband variability to find respective luminosity variations of the whole systems would also be desirable at the milli-mag precision level for both stars, in order to constrain the continuum level of the variations. We ask for highest possible accuracy up to the milli-mag level.

Observation at two observatories over only 3 nights in 1994 of propagating clumps in WR135 (Lepine et al. 2000, AJ, 120, 3201: their Fig. 2). Note how the emission sub-peaks from clumping move outward on the line profile as a result of radial outflow throughout the spherical wind seen in projection.