Red Rain Cells of Kerala as a Possible Carrier of the Diffuse Interstellar Bands and the UV Extinction Bump

Abstract

Despite various proposals, no conclusive identification exists for the carriers of diffuse interstellar absorption bands DIBs and the UV extinction bump at 217.5 nm. The red rain cells of Kerala show strong absorption features near 216.5 nm and several weak absorption features in the wavelength region 400 to 900 nm which are superimposed on a broader blue-UV absorption peak. The red pigment extracted from the cells show strong peaks at 334 nm and 440 nm along with multitude of weak peaks. The measured absorption peaks are compared with that of DIBs and the UV bump. The higher peak widths for red cells in comparison with DIBs is attributed to the temperature difference between space environment and laboratory. Our results of the absorption spectra of red rain cells show significant correlation with the reported wavelengths of numerous DIBs and the UV extinction bump of the interstellar medium, thus showing that the red rain cells, which are of suspected extraterrestrial origin, is a plausible carrier of DIBs and the UV extinction bump.