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K.C. Sahu (STScI), S. Kane (University of Tasmania)
The observed spectra of the microlensed sources towards the Galactic bulge may be used as a tool for studying the kinematics and extinction effects in the Galactic bulge. We have used the ESO 3.6m telescope with the ESO Faint Object Spectrograph and Camera to obtain moderate resolution spectra of 17 microlensed sources towards the Galactic bulge. For 8 sources, the spectra cover the wavelength region 5230 to 6970 A, and for the rest, the wavelength coverage is 3800 to 6970 A. The observed spectra have been modeled to determine the spectral types and extinction characteristics of the source stars. The microlensed sources clearly show an extinction offset of \Delta E(B-V) = 0.25 compared to the non-microlensed sources, which suggests that a large fraction of the lensing events are caused by stars within the Galactic bulge. This is further supported by a clear correlation between the timescale of the event and the extinction. The observed spectra along with the details of the modeling will be shown, and further implications of the results will be discussed.