The large scale distribution of PAHs in the Galaxy

Details The large scale distribution of PAHs in the Galaxy The large scale distribution of PAHs in the Galaxy

Jun 1994

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1994a%26a...286..203g&link_type=abstract

Astronomy and Astrophysics 286, 203-210 (1994)

Astronomy and Astrophysics

Astrophysics

43

Galaxy: Structure, Ism: General, Ism: Molecular, Ism Dust: Extinction, Infrared: Ism: Lines And Bands

Scientific paper

AROME, concerning the general emission of the Galaxy at 3.3μm : continuum and emission feature. Maps of the galactic plane are presented for galactic longitudes -60deg< LII < 60deg and latitudes -5deg< BII < 5deg. The continuum shows the exponential disk plus bulge stellar distributions, and the feature shows the thin dust disk. We show that, at large scale, the variations of the 3.3μm-feature/100μm and 12μm/100μm ratios can be interpreted in terms of extinction along the line of sight. We derive the following generic galactic dust colors for the diffuse medium: {DELTA}{lambda.epsilon_lambda_}(3.3μm-feature)/{lambda.epsilon_lambda_}(100) = 2.5+/-0.4 10^-3^, and {lambda.epsilon_lambda_}(12)/{lambda.epsilon_lambda_}(100) = 0.31+/-0.03. We show that there is no evidence for large scale variations of these colors, neither with the galactocentric distance, nor with the nature of the gas in which the emitting dust is located, neutral or molecular. This is interpreted as a strong argument in favor of a universal galactic mixture of dust grains. We show that the value of the 12/100 ratio can only be explained with a dust model including large molecules a few Angstroems size. The observation of the 3.3μm feature indicates that a significant fraction of these molecules may be Polycyclic Aromatic Hydrocarbons (PAHs). In this hypothesis, our results imply a homogeneous mixing of the PAHs into the general interstellar medium and a mass abundance of 3 to 8 % of the cosmic carbon. We show that these observational facts are marginally compatible with the hypothesis of mass-losing carbon stars being the main sites of PAH production in the Galaxy. We suggest that direct formation of PAHs in interstellar clouds may also occur.

Affiliated with

Also associated with

No associations

Rating

The large scale distribution of PAHs in the Galaxy 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 The large scale distribution of PAHs in the Galaxy, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The large scale distribution of PAHs in the Galaxy will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1862109