Infrared extinction in the Inner Milky Way through the red clump giants

While the shape of the extinction curve on the infrared is considered to be set and the extinction ratios between infrared bands are usually taken to be approximately constant, a recent number of studies point either to a spatially variable behavior on the exponent of the power law or to a different extinction law altogether. In this paper, we propose a method to analyze the overall behavior of the interstellar extinction by means of the red-clump population, and we apply it to those areas of the Milky Way where the presence of interstellar matter is heavily felt: areas located in 5 deg<l<30 deg and b=0 deg. We show that the extinction ratios traditionally used for the near infrared could be inappropriate for the inner Galaxy and we analyze the behavior of the extinction law from 1 to 8 microns.