J/A+A/662/A81 CRIRES NIR-DIBs (Ebenbichler+, 2022)
CRIRES high-resolution near-infrared spectroscopy of diffuse interstellar band
profiles.
Detection of 12 new DIBs in the YJ band and the introduction of a combined ISM
sight line and stellar analysis approach.
Ebenbichler A., Postel A., Przybilla N., Seifahrt A., Wessmayer D.,
Kausch W., Firnstein M., Butler K., Kaufer A., Linnartz H.
<Astron. Astrophys. 662, A81 (2022)>
=2022A&A...662A..81E 2022A&A...662A..81E (SIMBAD/NED BibCode)
ADC_Keywords: Interstellar medium ; Stars, supergiant ; Spectra, infrared
Keywords: dust, extinction - ISM: lines and bands - ISM: molecules -
line: profiles - stars: early-type - supergiants
Abstract:
A high spectral resolution investigation of diffuse interstellar bands
(DIBs) in the near-infrared (YJ band) is conducted to test new
methods, to confirm and improve existing parameters, and to search for
new DIBs. Methods: The CRyogenic high-resolution InfraRed Echelle
Spectrograph (CRIRES) on the European Southern Observatory's Very
Large Telescope was employed to obtain spectra of four reddened
background supergiant stars (HD 183143, HD 165784, HD 92207,
HD 111613) and an unreddened comparison star (HD 87737) at the highest
resolution of R∼100000 currently achievable at near-infrared
wavelengths. The correction for telluric absorption was performed by a
modelling approach. Non-local thermodynamic equilibrium spectral
modelling of available optical and the new near-infrared spectra
facilitated a comprehensive characterisation of the atmospheric
properties of the background stars. A more precise and accurate
determination of the reddening law along the sight lines could be
achieved than feasible before by comparison of the observed and model
spectral energy distributions. For DIBs that overlap with stellar
lines the DIB profile shapes could be recovered. Results: Seventeen
known near-infrared DIBs were confirmed, and 12 previously unknown and
generally weaker DIBs were identified in the YJ band. Three DIBs that
show uniform profiles along all sight lines were identified, possibly
connected to transitions from a common lower state of the same
carrier. The divergent extinction curve towards the frequently
discussed DIB standard star HD 183143 could be reproduced for the
first time, requiring extra absorption by ∼3.5 mag due to polycyclic
aromatic hydrocarbons (PAHs) to match the ultraviolet extinction bump.
This extra absorption probably stems from a circumstellar bubble lying
in front of the star which is intersected tangentially by the line of
sight.
Description:
The spectra were used for DIB measurements in the publication. They
were obtained by oCRIRES at VLT during filler programmes. All spectra
are in vacuum wavelengths in the barycentric restframe. Flux values
are in arbitrary units for HD 183143 and HD 165784 and normalized for
HD 111613 and HD 92207.
Objects:
--------------------------------------------------
RA (2000) DE Designation(s)
--------------------------------------------------
12 51 17.98 -60 19 47.2 HD 111613 = V* DS Cru
18 08 38.59 -21 26 58.4 HD 165784 = V* V4381 Sgr
19 27 26.56 +18 17 45.2 HD 183143 = V* HT Sge
10 37 27.07 -58 44 00.0 HD 92207 = V* V370 Car
--------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 61 80 *Characterisation of the detected DIBs and
new DIB candidates
list.dat 86 70 List of spectra
sp/* . 70 Individual spectra
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Note on tablea1.dat: Non-detection of DIBs are a result either of a strength
too low for detection or of missing spectral coverage.
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Byte-by-byte Description of file: tablea1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Star Star name
11- 15 I5 --- DIB DIB name
16- 18 A3 --- n_DIB Note on DIB (1)
20 I1 --- r_DIB Reference for DIB (2)
22- 28 F7.1 0.1nm lambda0air Rest wavelength, λ0,air,
in the barycentric rest frame (3)
30- 32 F3.1 0.1nm e_lambda0air rms uncertainty on lambda0air
34- 40 F7.1 0.1nm lambdavac Central wavelength in vacuum, λvac,
in the barycentric rest frame
42- 44 I3 0.1pm EW Equivalent width
46- 47 I2 0.1pm e_EW rms uncertainty on EW
49- 52 F4.1 % Ac Central depth
54- 57 F4.1 % e_Ac rms uncertainty on Ac
59- 61 F3.1 0.1nm FWHM Full width at half maximum
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Note (1): Notes for stellar blends as follows:
a = MgII, λair = 9631.891, 9632.430Å
b = FeII, λair = 10501.504Å
c = NI, λair = 10506.997Å
d = HeI, λair = 11044.983Å
e = CI, λair = 11801.098Å
f = HeI, λair = 11969.060, 11969.464Å
Note (2): Referencas as follows:
1 = Joblin et al. (1990Natur.346..729J 1990Natur.346..729J)
2 = Foing & Ehrenfreund (1994Natur.369..296F 1994Natur.369..296F)
3 = Groh et al. (2007A&A...465..993G 2007A&A...465..993G, Cat. J/A+A/465/993)
4 = Cox et al. (2014A&A...569A.117C 2014A&A...569A.117C)
5 = Hamano et al. (2015ApJ...800..137H 2015ApJ...800..137H)
6 = This work
Note (3): Rest wavelengths have a systematic error of ±0.3Å due to the
double KI components (see Section 5).
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 62 A62 --- Title Title of the spectrum file
64- 86 A23 --- FileName Name of the spectrum file in subdirectory sp
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Byte-by-byte Description of file: sp/*
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 F10.4 0.1nm lambda Barycentric wavelength in vacuum
12- 25 F14.5 --- Flux Flux (1)
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Note (1): Flux values are in arbitrary units for HD 183143 and HD 165784 and
normalized for HD 111613 and HD 92207.
--------------------------------------------------------------------------------
Acknowledgements:
Alexander Ebenbichler, alexander.ebenbichler(at)uibk.ac.at
(End) Alexander Ebenbichler [Univ. Innsbruck], P. Vannier [CDS] 06-May-2022