Issue |
A&A
Volume 689, September 2024
|
|
---|---|---|
Article Number | A38 | |
Number of page(s) | 10 | |
Section | Interstellar and circumstellar matter | |
DOI | https://doi.org/10.1051/0004-6361/202450297 | |
Published online | 29 August 2024 |
Volume density maps of the 862 nm DIB carrier and interstellar dust
Hints on the role of carbon-rich ejecta from AGB stars★
1
ACRI-ST, Centre d’Etudes et de Recherche de Grasse (CERGA),
10 Av. Nicolas Copernic,
06130
Grasse, France
e-mail: nick.cox@acri-st.fr
2
ACRI-ST,
260 Route du Pin Montard,
Sophia-Antipolis, France
3
GEPI, Observatoire de Paris, Université PSL, CNRS,
5 place Jules Janssen,
92195
Meudon, France
Received:
9
April
2024
Accepted:
2
June
2024
Context. The carbonaceous macromolecules imprinting the numerous absorptions called diffuse interstellar bands (DIBs) in astronomical spectra are omnipresent in the Galaxy and beyond. They represent a considerable reservoir of organic matter. However, their chemical formulae, formation, and destruction sites remain unknown. Their spatial distribution and the local relation to other interstellar species is key to tracing their role in the lifecycle of organic matter.
Aims. Volume density maps bring local instead of line-of-sight distributed information and allow for new diagnostics to be captured. We present the first large-scale volume (3D) density map of a DIB carrier and compare it with an equivalent map of interstellar dust.
Methods. The DIB carrier map was obtained through hierarchical inversion of ~202 000 measurements of the 8621 nm DIB obtained with the Gaia-RVS instrument. It covers about 4000 pc around the Sun in the Galactic plane. We built a dedicated interstellar dust map based on the extinction towards the same target stars.
Results. At the ≃50 pc resolution of the maps, the shape of the 3D DIB distribution is found to be remarkably similar to the 3D distribution of dust. On the other hand, the DIB-to-dust local density ratio increases in low-dust areas. It is also increasing away from the disk, however, the minimum ratio is found to be shifted above the Galactic plane to Z=≃+50pc. Finally, the average ratio is also surprisingly found to increase away from the Galactic Center. We suggest that the three latter trends may be indications of a dominant contribution of material from the carbon-rich category of dying giant stars to the formation of the carriers. Our suggestion is based on recent catalogs of asymptotic giant branch (AGB) stars and estimates of the mass fluxes of their C-rich and O-rich ejecta.
Key words: stars: AGB and post-AGB / ISM: clouds / dust, extinction / evolution / ISM: lines and bands / ISM: structure
The DIB and extinction 3D maps are available at the CDS via anonymous ftp to cdsarc.cds.unistra.fr (130.79.128.5) or via https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/689/A38
© The Authors 2024
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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