J/A+A/689/A38 3D volume density map of the 862nm DIB carrier (Cox+, 2024)
Volume density maps of the 862 nm DIB carrier and interstellar dust.
Hints on the role of carbon-rich ejecta from AGB stars.
Cox N.L.J., Vergely J.L., Lallement R.
<Astron. Astrophys. 689, A38 (2024)>
=2024A&A...689A..38C 2024A&A...689A..38C (SIMBAD/NED BibCode)
ADC_Keywords: Interstellar medium ; Equivalent widths
Keywords: stars: AGB and post-AGB - ISM: clouds - dust, extinction - evolution -
ISM: lines and bands - ISM: structure
Abstract:
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.
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.
The DIB carrier map was obtained through hierarchical inversion of
202000 measurements of the 862.1nm DIB obtained with the Gaia-RVS
instrument. It covers about 4000pc around the Sun in the Galactic
plane. We built a dedicated interstellar dust map based on the
extinction towards the same target stars.
At the 50pc 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.
Description:
The 3D distribution of the carrier of the 862.1nm Diffuse Interstellar
Band (DIB) is presented in Cartesian coordinates in an 801x801x81
matrix representing a volume of 6kpcx6kpcx0.8kpc surrounding the Sun.
Voxels are 10pcx10pcx10pc cubes. The Sun coordinates are(0,0,0). The X
axis is directed to the Galactic Center. The Y axis is tangential to
the solar circle and follows the sense of rotation, the Z axis is
towards the North Galactic Pole. X and Y vary between -3kpc and +3kpc,
Z vary between -0.4kpc and +0.4kpc.
The represented quantity is the local (at coordinates X, Y, Z)
gradient of the DIB equivalent width, in Angstroem per parsec unit.
Distances from the Sun at which the density becomes uncertain are
displayed in Figure 2 of the article. They can be asked from the
authors if needed with precision.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
DIB862nmdensity_cube.h5 512 337790 DIB and extinction 3D maps
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Acknowledgements:
Rosine Lallement, rosine.lallement(at)obspm.fr
(End) Patricia Vannier [CDS] 20-Aug-2024