J/A+A/695/A205 Profile parameters of the 6196Å DIB (Piecka+, 2025)
Survey of profile parameters of the 6196 Å diffuse interstellar band.
From uniform profiles to Doppler splitting and blueshifts.
Piecka M., Hutschenreuter S., Alves J.
<Astron. Astrophys. 695, A205 (2025)>
=2025A&A...695A.205P 2025A&A...695A.205P (SIMBAD/NED BibCode)
ADC_Keywords: Stars, early-type ; Interstellar medium ; Spectroscopy
Keywords: ISM: kinematics and dynamics - ISM: lines and bands - ISM: structure
Abstract:
The diffuse interstellar band (DIB) at 6196Å exhibits notable
profile variations across the Milky Way. This study addresses three
open issues: the unusual broadening of the DIB profile towards Upper
Sco, the lack of profile variations towards stars near eta Car, and
the origin of the blueshift observed in Sco OB1. Using archival
spectra of 453 early-type stars across the Galactic disk and in its
proximity, we created a catalogue of the DIB's profile parameters. Our
analysis identifies Doppler-split components within the DIB profiles
across most regions but finds no evidence for these splits being able
to account for the observed broadening (23km/s) in Upper Sco or other
regions like Orion, Vela OB2, and Melotte 20 (alpha Per cluster). We
propose that neither the ages of the studied stellar populations nor
the distances between clusters and nearby clouds contribute
significantly to the broadening. However, we detect a gradient in the
FWHM within the Sco-Cen and Orion regions, where broadening decreases
with distance from the star-forming centres. This result points to a
possible connection between the DIB broadening and star formation
(likely via the impact of recent supernovae). Regarding the Carina
Nebula, we confirm the lack of DIB profile variations in a small
region near eta Car, although an adjacent southern area exhibits
significant variations, comparable to those in Upper Sco. In addition
to the Carina Nebula, we find that the Rosette Nebula and NGC 6405
also show consistently narrow profiles (<20km/s) with minimal
deviations from the median over spatial scales of a few parsecs.
Finally, regarding the origin of the blueshift observed in Sco OB1, we
use a comparison with the Lagoon Nebula and argue that the most
natural explanation is the presence of an unresolved kinematic
component in the profile of the DIB, shifting the measured centre of
the band.
Description:
Spectral data were obtained from ESO and ELODIE archives. A
multi-Gaussian model was fitted to the reduced spectra and the
following profile parameters were measured: DIB wavelength (at the
median of the profile), central depth, FWHM, and EW. The observed
targets were grouped according to their position in the sky and the
proximity of neighbouring relevant objects (clouds, stellar clusters).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
pha6196.dat 182 453 Observed targets and profile measurements
(table B1 + B2)
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Byte-by-byte Description of file: pha6196.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- Target Target ID
16- 17 I2 --- Group [0/11] ID of the group assigned to
the target
19- 25 A7 --- Label Label of the group assigned to the target
27- 45 A19 --- Subgroup Object in the vicinity of the target
47- 55 A9 --- AstroSource Source of astrometric measurements
57- 65 F9.5 deg GLON Galactic longitude
67- 77 F11.7 deg GLAT Galactic latitude
79- 84 F6.4 mas Plx ?=- Parallax
86- 91 F6.4 mas e_Plx ?=- Parallax uncertainty
93- 98 A6 --- SpectSource Source of the observed spectra
100-101 I2 --- Nspect Number of stacked spectra
103-110 F8.3 0.1nm b_Wave 16th percentile of profile wavelength
112-119 F8.3 0.1nm Wave 50th percentile of profile wavelength
121-128 F8.3 0.1nm B_Wave 84th percentile of profile wavelength
130-135 F6.4 --- b_Depth 16th percentile of central depth
137-142 F6.4 --- Depth 50th percentile of central depth
144-149 F6.4 --- B_Depth 84th percentile of central depth
151-155 F5.2 km/s b_FWHM 16th percentile of FWHM
157-161 F5.2 km/s FWHM 50th percentile of FWHM
163-167 F5.2 km/s B_FWHM 84th percentile of FWHM
169-172 F4.1 0.1pm b_EW 16th percentile of EW
174-177 F4.1 0.1pm EW 50th percentile of EW
179-182 F4.1 0.1pm B_EW 84th percentile of EW
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Acknowledgements:
Martin Piecka, martin.piecka(at)univie.ac.at
(End) Patricia Vannier [CDS] 26-Feb-2025