Correlation Statistics Analysis Of The Diffuse Interstellar Bands

Diffuse Interstellar Bands(DIBs) have been discovered almost 90 years, they are the hot targets for the scientists in the fields of astrophysics all the time. With the progress of science and technology, researchers have known about the DIBs more thoroughly, but none of the bands have been affirmed. Besides the observation, the scientists have developed some methods of DIBs confirmation, such as the spectrum simulation experiments, correlation analysis, etc. There are more than 540 bands have been observed so far which makes it is impossible to identify them one by one. We can seek the relationship between the DIBs and then explore the same family bands by analyzing correlation among them in order that we are able to study them more perfectly later.In this paper, we described the origin of the DIBs, the properties of absorption spectral lines and several ways of confirmation of them firstly. Besides, we still focused on the insufficient of the previous research. Then, we took the interstellar extinction into account and then chose the color index(E(B-V)) as the normalization parameter for equivalent widths(EW), which ruled out the shortage of the former classification works. The main results are the following:1. The correlations between 57 DIBs under the condition of normalization were calculated. We found that the coefficients became smaller comparing with the results by Xiang et al.(2012).2. According to the coefficients worked out, a few of DIBs had been classified into a real family. Among the nine broad DIBs(λ4428?, λ4501?, λ4726?, λ4763?, λ5362?, λ5487?, λ5705?, λ5780?) by Xiang et al.(2012), the four DIBs(λ5487?, λ5705?, λ5780?, λ6284?) were correlated well with each other(R≥0.7) and we thought they were the same group bands finally. Also, we argued that the five DIBs(λ5544?, λ5797?, λ6195?, λ6376?, λ6614?) of the 15 narrow DIBs(λ5544?, λ5797?, λ5809?, λ6113?, λ6196?, λ6203?, λ6234?, λ6270?, λ6376?, λ6379?, λ6425?, λ6521?, λ6614?, λ6660?, λ6699?) by Xiang et al.(2012) were the similar category bands.3. According to the relationships between the bands, λ6234? and λ6425?, λ6234? and λ6660?, λ6203? and λ6113?, λ6203? and λ6699? had been defined associated-bands. The six DIBs(λ6234?,λ6425?,λ6660?,λ6203?,λ6113?,λ6699?) were classified into a ‘family’ by Xiang et al.(2012). DIBs λ6234? correlated well with λ6425? and λ6660?, but the correlation of DIBs λ6425? and λ6660? was very poor; the bands λ6203? had a positive relationship with λ6113? and λ6699?, however, the correlation between λ6113? and λ6699? was not.