INFERENCE OF STEADY STELLAR WIND V(R) LAWS FROM OPTICALLY THIN EMISSION-LINES - III - INVERSION OF TOTAL LINE INTENSITY DISTRIBUTIONS

The variation with wavelength for a sequence of total intensities of s tellar wind lines is considered as a basis for deriving the wind veloc ity law upsilon(r). In particular, we focus on the case where the cont inuum formation in the wind is dominated by the free-free opacity so t hat the inner radius increases with wavelength, as is realized in some massive winds like those of the Wolf-Rayet stars. The line emission i n the wind occurs exterior to the continuum photosphere, hence lines o bserved at different wavelengths probe different regions of the wind a cceleration. A major consequence of these physical conditions is the o pportunity to infer upsilon(r), even if non-monotonic. Numerical examp les are given to test the method, in which smooth and non-smooth monot onic upsilon(r), non-monotonic upsilon(r), and the effects of noise ar e addressed. In the absence of noise, the inversion of the simulated d ata for radius r(lambda) and expansion velocity upsilon(lambda) is exc ellent. Even with noise at the 15% level, the recovery for r(lambda) r emains reasonably robust, though the results for upsilon(lambda) are m ore strongly affected. Although more sophisticated techniques are requ ired to infer upsilon(lambda) from noisy data, the simpler considerati ons presented here provide a basic theoretical framework for applying the inversion and indicate the potential of the method for deriving th e wind flow structure.