The well correlated DIBs at $\lambda\lambda$ 6196, 6614 {\AA} and their possible companions

TL;DR

This study investigates the correlations among five diffuse interstellar bands using high-resolution spectra, revealing strong linear relationships that suggest a common origin, possibly linked to PAH vibrational transitions.

Contribution

It is the first to analyze the relation between three weaker DIBs and two well-known ones, establishing high correlation coefficients and proposing a connection to PAH vibrational energies.

Findings

High correlation coefficients (up to 0.988) among the five DIBs.

Linear dependencies suggest a common origin for these DIBs.

Wavenumber spacings match vibrational energies of PAHs.

Abstract

Considered here is the interrelation between five diffuse interstellar bands (DIBs): $\lambda\lambda$ 5545, 6113, 6196, 6445 and 6614 \r{A}. Two DIBs ($\lambda$ 6196 and $\lambda$ 6614 \r{A}) have already been known as well correlated with each other; their relation with three other, weaker bands, was investigated for the first time. To accomplish this task high-resolution spectra ($\lambda/\Delta\lambda$ $\approx$ 100,000) with high signal-to-noise ratio (S/N) of 54 hot O -- B stars with reddening 0.12 -- 1.45 mag were used. Analysis of measured equivalent widths has allowed to establish linear dependencies and evaluate linear correlation coefficients as high as 0.968 -- 0.988 between the intensities of these five DIBs. Such a degree of correlation may indicate their common origin. Several spacings in wavenumbers found between these DIBs correspond to the energies of vibrational transitions in some PAHs resulting in IR emissions at $\lambda\lambda$ 16.4, 11.3, 7.7, 6.2 and 3.3 $\mu$m.