A Dust Lane Leading the Galactic Bar at Negative Galactic Longitudes

Abstract

Comparing the different wavelengths of the DIRBE integrated surface brightness maps at positive and negative Galactic longitudes on the plane near the Galactic center, it is shown that there exists a thick dust lane (between 1.0 and 2.6 mag of absorption in K) at negative longitudes (as compared to positive ones), which follows the "standard" interstellar extinction law. A likely explanation for this effect is the existence of a thick dust lane preceding the bar. This will have to be confirmed by future infrared surveys, such as DENIS or 2MASS, that will cover negative Galactic longitudes, where a heavy extinction dust lane about 2° wide, close to the Galactic plane, should be seen.