Joint spectral and polarimetric analysis of hot star wind transients

Abstract

The problem of deriving the evolution of stellar mass loss rate m( tau ) and asphericity a( tau ) from data on episodic polarization and absorption line strength variations is considered following the treatment by Brown and Wood. Their method, based on Fourier solution of a pair of coupled convolution equations, is tested on simulated data from a variety of hypothetical models for m( tau ) and a( tau ). Moreover, the authors investigate a new method which requires fewer data points than Fourier deconvolution and can be readily extended to the case of non-uniformly spaced and non-simultaneous (though overlapping) data for polarization and absorption measurements. This method provides a regularized solution in a space of differentiable functions (Sobolev space) and in the tests it proves to be as reliable as Fourier deconvolution. Moreover, various criteria for the choice of the regularization parameters are compared in view of the application to the analysis of real data. Both the methods considered are reliable for the estimation of m( tau ) and a( tau ) in the presence of realistic data noise.