Astrochemistry

Mapping the aliphatic hydrocarbon content of interstellar dust in the Galactic plane

By Keith Cowing
astro-ph.GA
August 2, 2022
Filed under
Mapping the aliphatic hydrocarbon content of interstellar dust in the Galactic plane
Map of the optical depth in 3.4 µm absorption feature for Field B in celestial coordinates (J2000) for the brightest 160 sources. Colour bars and contours indicate τ3.4 µm levels. On the left panel location of the sources are shown by black dots whose sizes are proportional to the optical depth values. On the right panel, sizes are proportional to the 3.4 µm flux values.

We implement a new observational method for mapping the aliphatic hydrocarbon content in the solid phase in our Galaxy, based on spectrophotometric imaging of the 3.4 μm absorption feature from interstellar dust.

We previously demonstrated this method in a field including the Galactic Centre cluster. We applied the method to a new field in the Galactic centre where the 3.4 μm absorption feature has not been previously measured and we extended the measurements to a field in the Galactic plane to sample the diffuse local interstellar medium, where the 3.4 μm absorption feature has been previously measured.

We have analysed 3.4 μm optical depth and aliphatic hydrocarbon column density maps for these fields. Optical depths are found to be reasonably uniform in each field, without large source-to-source variations.

There is, however, a weak trend towards increasing optical depth in a direction towards b=0∘ in the Galactic centre. The mean value of column densities and abundances for aliphatic hydrocarbon were found to be about several ×1018cm−2 and several tens ×10−6, respectively for the new sightlines in the Galactic plane. We conclude that at least 10-20% of the carbon in the Galactic plane lies in aliphatic form.

B. Günay, M. G. Burton, M. Afşar, T. W. Schmidt

Subjects: Astrophysics of Galaxies (astro-ph.GA); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Cite as: arXiv:2208.01058 [astro-ph.GA] (or arXiv:2208.01058v1 [astro-ph.GA] for this version)
Journal reference: Monthly Notices of the Royal Astronomical Society, 2022, stac1482
Submission history
From: Burcu Günay
[v1] Mon, 1 Aug 2022 18:00:11 UTC (2,091 KB)
https://arxiv.org/abs/2208.01058
Astrobiology, Astrochemistry,

SpaceRef co-founder, Explorers Club Fellow, ex-NASA, Away Teams, Journalist, Space & Astrobiology, Lapsed climber.