H2 Emission Spectra with New Formation Pumping Models

Details H2 Emission Spectra with New Formation Pumping Models H2 Emission Spectra with New Formation Pumping Models

Nov 2001

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2001apj...561..843t&link_type=abstract

The Astrophysical Journal, Volume 561, Issue 2, pp. 843-857.

Astronomy and Astrophysics

Astronomy

24

Ism: Dust, Extinction, Infrared: Ism, Ism: Lines And Bands, Ism: Molecules, Molecular Processes

Scientific paper

It has been predicted that H2 newly formed on the surface of dust grains should be in highly vibrationally and rotationally excited states in the ground electronic state via the formation pumping mechanism. This suggests that the rovibrational emission spectrum of H2 may be detectable even in regions without a source of UV pumping or dynamical excitation. Moreover, the infrared H2 emission arising from formation pumping can be a new probe that will directly show us the spot where the evolution from H I clouds to H2 clouds occurs. In the present work, we investigate the pure effects of formation pumping in infrared H2 emission spectra with our new formation pumping models. We build up our formation pumping models for H2 newly formed on icy mantles, carbonaceous dust, and silicate dust, on the basis of the recent progress of basic studies about the H2 formation process on the surface of dust grains. Then, we calculate the H2 emission spectra with our new formation pumping models, considering the early stage of an evolving region from H I clouds to H2 clouds dominated by the H2 formation process on the surface of dust grains, of uniform H I density nH=103 cm-3 and the gas temperature T=10 K, in the cold interior of interstellar clouds under a weak ultraviolet (UV) radiation field. We find that the resulting infrared H2 emission spectra dominated by formation pumping can be discriminated from those dominated by UV pumping as well as have information about the property of dust. We also find that the fluxes of the most intense emission lines arising from formation pumping should be strong enough to be detected. In the wavelength range λ >~ 1.6 μm, if the line intensities of many transitions from higher rotational states such as 1-0 S(3), 1-0 S(5), and 1-0 S(7) become stronger than that of the 1-0 S(1) transition, it should be the evidence of H2 emission arising from formation pumping. In the wavelength range λ <~ 1.6 μm, if many transitions from higher vibrational states are detected, the emission should be originated from H2 newly formed on icy mantles or silicate dust. On the contrary, if not, the emission should be from H2 formed on carbonaceous dust.

Affiliated with

Also associated with

No associations

Rating

H2 Emission Spectra with New Formation Pumping Models does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with H2 Emission Spectra with New Formation Pumping Models, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and H2 Emission Spectra with New Formation Pumping Models will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1234953