A search for naphthalene in diffuse interstellar clouds

Authors

  • Susana Iglesias-Groth,

    Corresponding author
    1. Instituto de Astrofisíca de Canarias, 38200 La Laguna, Tenerife, Canary Islands, Spain
    2. Departamento de Astrofísica, Universidad de La Laguna, E-38205 La Laguna, Tenerife, Spain
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  • Jonay González Hernández,

    1. Instituto de Astrofisíca de Canarias, 38200 La Laguna, Tenerife, Canary Islands, Spain
    2. Departamento de Astrofísica, Universidad de La Laguna, E-38205 La Laguna, Tenerife, Spain
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  • A. Manchado

    1. Instituto de Astrofisíca de Canarias, 38200 La Laguna, Tenerife, Canary Islands, Spain
    2. Departamento de Astrofísica, Universidad de La Laguna, E-38205 La Laguna, Tenerife, Spain
    3. Consejo Superior de Investigaciones Científicas (CSIC), Serrano 117, 28006 Madrid, Spain
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E-mail: sigroth@iac.es

ABSTRACT

We have obtained high-resolution optical spectroscopy of 10 reddened O-type stars with Ultraviolet and Visual Echelle Spectrograph at Very Large Telescope to search for interstellar bands of the naphthalene cation (C10H8+) in the intervening clouds. No absorption features were detected near the laboratory strongest band of this cation at 6707 Å except for star HD 125241 (O9 I). Additional bands in the optical spectrum of this star appear to be consistent with other transitions of this cation. Under the assumption that the bands are caused by naphthalene cations, we derive a column density inline image= (1.2 ± 0.3) × 10 13 cm−2 similar to the column density claimed in the Perseus complex star Cernis 52. The strength ratio of the two prominent diffuse interstellar bands at 5780 and 5797 Å suggests the presence of a σ-type cloud in the line of sight of HD 125241.

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