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Table · dataset · 2018

Equivalent widths of 8 DIBs for 186 O & B stars

Listed in IVOA Registry (Virtual Observatory)

We study the behavior of eight diffuse interstellar bands (DIBs) in different interstellar environments, as characterized by the fraction of hydrogen in molecular form (f_H2_), with comparisons to the corresponding behavior of various known atomic and molecular species.

Description

The equivalent widths of the five "normal" DIBs ({lambda}{lambda}5780.5, 5797.1, 6196.0, 6283.8, and 6613.6), normalized to E_B-V_, show a "lambda-shaped" behavior: they increase at low f_H2_, peak at f_H2_~0.3, and then decrease.

The similarly normalized column densities of Ca, Ca+, Ti+, and CH+ also decline for f_H2_>0.3. In contrast, the normalized column densities of Na, K, CH, CN, and CO increase monotonically with fH2, and the trends exhibited by the three C_2_ DIBs ({lambda}{lambda}4726.8, 4963.9, and 4984.8) lie between those two general behaviors. These trends with f_H2_ are accompanied by cosmic scatter, the dispersion at any given f_H2_ being significantly larger than the individual errors of measurement.

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The lambda-shaped trends suggest the balance between creation and destruction of the DIB carriers differs dramatically between diffuse atomic and diffuse molecular clouds; additional processes aside from ionization and shielding are needed to explain those observed trends. Except for several special cases, the highest W{lambda}(5780)/W{lambda}(5797) ratios, characterizing the so-called "sigma-zeta effect," occur only at f_H2_<0.2.

We propose a sequence of DIBs based on trends in their pair-wise strength ratios with increasing f_H2_. In order of increasing environmental density, we find the {lambda}6283.8 and {lambda}5780.5 DIBs, the {lambda}6196.0 DIB, the {lambda}6613.6 DIB, the {lambda}5797.1 DIB, and the C_2_ DIBs.

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IVOA Registry (Virtual Observatory)ivo://cds.vizier/j/apj/850/19412 d agoJSON v1
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access_levelsource · IVOA Registryconnector:ivoa_registry@1.0.0
concepts[field].local:field:astronomymapping · IVOA Registryconnector:ivoa_registry@1.0.0
concepts[modality].ivoa_waveband:opticalsource · IVOA Registryconnector:ivoa_registry@1.0.0
descriptionsource · IVOA Registryconnector:ivoa_registry@1.0.0rr.resource.res_description
license_textsource · IVOA Registryconnector:ivoa_registry@1.0.0
publication_datesource · IVOA Registryconnector:ivoa_registry@1.0.0
titlesource · IVOA Registryconnector:ivoa_registry@1.0.0rr.resource.res_title
updated_datesource · IVOA Registryconnector:ivoa_registry@1.0.0