L(alpha)-induced two-photon absorption of visible light emitted from an O-type star by H2(+) ions located near the surface of the Stromgren sphere surrounding the star : A possible explanation for the diffuse interstellar absorption bands (DIDs).

Author:: Glownia, James H.
Published:: May 1, 1994.
Physical Description:: 1 electronic document
Additional Creators:: Sorokin, Peter P.

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Summary:

In this paper, a new model is proposed to account for the DIB's (Diffuse Interstellar Bands). In this model, the DIB's result from a non-linear effect: resonantly-enhanced two-photon absorption of H(2+) ions located near the surface of the Stromgren sphere that surrounds an O- or B- type star. The strong light that is required to 'drive' the two-photon transition is provided by L(alpha) light emerging from the Stromgren sphere that bounds the H II region surrounding the star. A value of approximately 100 micro W/sq cm is estimated for the L(alpha) flux at the Stromgren radius, R(s), of a strong (O5) star. It is shown that a c.w. L(alpha) flux of this intensity should be sufficient to induce a few percent absorption for visible light radiated by the same star at a frequency (omega2) that completes an allowed two-photon transition, provided (1) the L(alpha) radiation happens to be nearly resonant with the frequency of a fully-allowed absorber transition that effectively represents the first step in the two-photon transition, and (2) an effective column density approximately 10(sup18)/sq cm of the absorber is present near the Stromgren sphere radius, R(sub s).

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ASTRONOMY

Collection:

NASA Technical Reports Server (NTRS) Collection.

Note:

Document ID: 19950009430.
Accession ID: 95N15845.
NASA. Ames Research Center, The Diffuse Interstellar Bands: Contributed Papers; p 99-104.

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