2011A&A...531A..68K

We analyse a high-resolution, high signal-to-noise spectrogram of the hot reddened star Trumpler16112 to find relationships between the physical parameters of the intervening interstellar medium (e.g., the rotational temperature of the CN radical) and the intensities of interstellar lines/bands. We report on the discovery of an interstellar cloud that shows an exceptionally high rotational temperature of CN (4.5K) and unusually strong CaI and FeI interstellar lines. This rare CaFe-type cloud seemingly contains no diffuse band carriers.