Title:Dissecting the winds of the most massive stars using long-baseline interferometry: 
Predictions from 1-D and 2-D NLTE radiative transfer models

Abstract:
The most massive stars have dense winds which hide, partially or completely, the hydrostatic 
surface of the star from our direct view. Since such outflows are compact, and massive stars are 
located at far distances, all the knowledge that we have acquired about them over the past decades 
comes from the spatially-integrated spectrum. Long-baseline interferometry is currently the only 
technique capable of providing the milli-arcsecond resolution observations which are needed to
resolve the winds of massive stars. Since we are still one step away from reconstructing images 
from interferometric data, we are left to analyze the so-called visibilities, phases, and closure 
phases. Not surprisingly, the interpretation of these quantities is not straightforward, but it can 
provide constraints on the size and geometry of the stellar continuum emission and within the 
spectral lines. In this talk I will present predictions and interpretations of the interferometric 
observables of massive stars based on the NLTE, full line-blanketed radiative transfer code CMFGEN 
and the Busche & Hillier (2005) code. I will show how interferometric observables relate to the
fundamental parameters of the central star, such as mass-loss rate, wind terminal velocity, 
temperature, and luminosity. In addition, I will present predictions of monochromatic images and 
show how dramatically different the most massive stars will look like if they have a non-spherical 
wind.