A Study On The Correlations Between Diffuse Interstellar Bands

The diffuse interstellar bands (DIBs) are absorption features in the widely opticalregion between ultraviolet (UV) and infrared (IR) of interstellar material. After it hasbeen studied for nearly nine decades, more than 540 DIBs have been detected.Unfortunately, none of their carriers have been accurately identified. For the identificationof diffuse interstellar bands,the analysis of correlations between the diffuse interstellarbands is still one of the challenging topics in astronomical spectroscopy.In the present thesis, we firstly introduced the basic method of the analysis ofcorrelations. And then, we studied the correlation of equivalent widths (EWs) of 52diffuse interstellar bands. The main results are the following:1. The correlations between the equivalent widths of 52 diffuse interstellar bandswere analyzed. In this work, a total of 52 DIBs were available (λ4428(?),λ4501(?),λ4726(?),λ4734(?),λ4763(?),λ4882(?),λ4963(?),λ4984(?),λ5175(?),λ5362(?),λ5449(?),λ5487(?),λ5512(?),λ5535(?),λ5544(?),λ5705(?),λ5707(?),λ5760(?),λ5763(?),λ5766(?),λ5769(?),λ5773(?),λ5776(?),λ5778(?),λ5780(?),λ5793(?),λ5795(?),λ5797(?),λ5809(?),λ5819(?),λ5829(?),λ5844(?),λ5850(?),λ6010(?),λ6065(?),λ6090(?),λ6113(?),λ6177(?),λ6196(?),λ6203(?),λ6234(?),λ6270(?),λ6284(?),λ6376(?),λ6379(?),λ6425(?),λ6439(?),λ6521(?),λ6614(?),λ6660(?),λ6699(?) andλ6729(?) DIBs) and the correlation coefficients betweenthe equivalent widths of the DIBs were worked out. Among 785 correlation coefficients 8couples show a strong correlation (R≥0.95), 419 couples show a rather good correlation(0.70≤R<0.95) and 358 couples show a non-correlation.2. According to the values of the correlation coefficients, some of the 45 DIBs hadbeen classified into one group or a"family". Among 427 correlation coefficients (R≥0.70),we found that theλ4763(?),λ5544(?),λ5705(?),λ5780(?),λ5797(?),λ5809(?),λ6113(?),λ6196(?),λ6203(?),λ6234(?),λ6270(?),λ6284(?),λ6376(?),λ6379(?),λ6425(?),λ6521(?),λ6614(?) andλ6699(?) DIBs are well correlated one another.3. According to the values of the FWHM of the DIB and the correlationcoefficients between the DIBs, some of the 45 prominent DIBs had been divided into twoisolated families. The observations of HD 183143 published by Hobbs et al. (2009)showed that theλ4763(?),λ5705(?),λ5780(?) andλ6284(?) DIBs are broader than theλ5544(?),λ5797(?),λ5809(?),λ6113(?),λ6196(?),λ6203(?),λ6234(?),λ6270(?),λ6376(?),λ6379(?),λ6425(?),λ6521(?),λ6614(?) andλ6699(?) DIBs. We had divided some the 45 DIBs into two isolated families according to the values of the FWHM of the DIBs and thecorrelations coefficients between the DIBs: (1) the nine broad and well correlated DIBsλ4428(?),λ4501(?),λ4726(?),λ4763(?),λ5362(?),λ5487(?),λ5705(?),λ5780(?),λ6284(?) DIBs;(2) the 15 narrow and well correlated DIBsλ5544(?),λ5797(?),λ5809(?),λ6113(?),λ6196(?),λ6203(?),λ6234(?),λ6270(?),λ6376(?),λ6379(?),λ6425(?),λ6521(?),λ6614(?),λ6660(?) andλ6699(?) DIBs.