Nebula spectrum analysis

Evidence of a relation between carbon particles and DIBs can be found in the analysis of the Red Rectangle spectrum. This object is a losing mass carbon star probably evolving to a planetary nebula phase. Diverse spectroscopic studies have revealed the good agreement between the emission lines found at 5,797, 5,850, 6,379, and 6,614 A and some of the most intense diffuse bands of the interstellar medium. It is likely that the carrier of some of these interstellar bands is also present in the material ejected by this object. 

P13.30 The question of whether to use CN or CH within the interstellar cloud of constellation Ophiuchus for the determination of the temperature of the cosmic background radiation depends upon which one has a rotational spectrum that best spans blackbody radiation of 2.726 K. Given flo(CH) = 14.90 cm-1, the rotational constant that is needed for the comparative analysis may be calculated from the 226.9 GHz spectral line of the Orion Nebula. Assuming that the line is for the l2Cl4N isotopic species and J + 1 <— 7=1, which gives a reasonable estimate of the CN bond length (117.4 pm), the CN rotational constant is calculated as follows. 

---