The EDIBLES survey. V. Line profile variations in the lambdalambda5797, 6379, and 6614 diffuse interstellar bands as a tool to constrain carrier sizes

Several diffuse interstellar bands (DIBs) have profiles with resolved sub-peaks that resemble rotational of large molecules. Analysis these can constrain the sizes and geometries DIB carriers, especially if exhibit clear variations along lines sight probing different physical conditions. Using extensive data set from EDIBLES survey we searched for systematic in peak-to-peak separation $\lambda\lambda$5797, 6379, 6614 DIBs a single dominant cloud. We used spectra twelve single-cloud to measure band profile substructures DIBs. adopted contour formalism infer constant each carrier excitation temperature lines. compared constants linear spherical molecules estimate sizes. All three peak separations vary systematically between sight, indicating correlated changes temperatures. derived $B_{6614}$=$(22.2\pm8.9)\times 10^{-3}$ cm$^{-1}$, consistent previous estimates. Assuming similar $\lambda$6614 assuming carrier, found B$_{5797}^{\rm linear}=(5.1\pm2.0)\times10^{-3}~{\rm cm}^{-1}$ B$_{6379}^{\rm linear} =(2.3\pm0.9)\times10^{-3}~{\rm cm}^{-1}$. If carriers those however are species, their half value, $B_{5797}^{\rm spherical} = (2.6\pm1.0)\times10^{-3}~{\rm $B_{6379}^{\rm (1.1\pm0.4)\times10^{-3}~{\rm molecule range 7--9 carbon atoms ($\lambda$6614 linear) 77--114 ($\lambda$6379, spherical).