On the optical extinction and distance of GRS 1915+105

Abstract

Based on new millimeter and radio observations, we reevaluate the total hydrogen column density along the line of sight to the microquasar GRS 1915+105 to cm-2. Our value is consistent with the one derived from X-ray measurements, namely ( cm-2 (Ebisawa et al. [CITE]). Using the empirical law between the visual extinction and the total column density of hydrogen, Av is found to 19.6 ± 1.7 mag. This result is ~mag lower than previously thought, and therefore, a reevaluation of infrared fluxes after derredening is needed. The revisited kinematic study allows to give a lower limit to the distance of GRS 1915+105 , namely 6.0 kpc. Taking into account the most accurate upper limit of distance inferred from radio data ( kpc, Fender et al. [CITE]) as well as this lower limit, this implies a distance of kpc.