A comparison of the spectral index distribution with the molecular emission. The color representation corresponds to the spatially resolved spectral index map between 74 and 330 MHz, while the overlaid contours trace the ¹²C0 (J = 1 − 0) emission integrated between  − 10 and  − 1 km s^-1 (Zhang et al. 2010). The positions where OH(1720 MHz) maser emission were detected are indicated with open white diamonds (Hoffman et al. 2003; Hewitt 2009).