CRIRES high-resolution near-infrared spectroscopy of diffuse interstellar band profiles

Ebenbichler, A.; Postel, A.; Przybilla, N.; Seifahrt, Andreas; Weßmayer, D.; Kausch, W.; Firnstein, M.; Butler, K.; Kaufer, A.; Linnartz, H.

doi:10.1051/0004-6361/202142990

Cited by 18 publications

(20 citation statements)

References 83 publications

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“…The large DIB EWs toward the heavily reddened lines of sight enabled us to detect 54 DIBs, 25 of which were newly discovered by our observations. We also independently detected nine of 12 DIBs newly detected in Ebenbichler et al (2022). We succeeded in detecting DIBs as weak as 10 m Å in the NIR range.…”

Section: Discussionmentioning

confidence: 89%

“…As a result of the search for new DIBs in Section 3.3, we detected 34 new DIBs, nine of which were independently detected by Ebenbichler et al (2022). In addition, we also detected eight candidates.…”

Section: Detected and Candidate Dibsmentioning

confidence: 87%

“…The black squares show the DIBs detected in the literature(Joblin et al 1990;Foing & Ehrenfreund 1994;Groh et al 2007). The green diamonds show the DIBs detected inEbenbichler et al (2022). The light blue triangles show the candidate DIBs in this study.…”

mentioning

confidence: 81%

“…Therefore, the carrier abundance of the DIBs tends to be reduced at longer wavelengths, suggesting that the NIR DIBs trace molecular species that are less abundant in interstellar clouds and/or have (Joblin et al 1990;Foing & Ehrenfreund 1994;Groh et al 2007). The green diamonds show the DIBs detected in Ebenbichler et al (2022). The gray and black circles show the DIBs in the range of 4000-9000 Å (Fan et al 2019) and the H-band DIBs (Cox et al 2014), respectively.…”

Section: Observational Biasesmentioning

confidence: 99%

“…The black squares show the DIBs detected in the literature(Joblin et al 1990;Foing & Ehrenfreund 1994;Groh et al 2007). The green diamonds show the DIBs detected inEbenbichler et al (2022). The gray and black circles show the DIBs in the range of 4000-9000 Å(Fan et al 2019) and the H-band DIBs(Cox et al 2014), respectively.…”

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confidence: 99%

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Survey of Near-infrared Diffuse Interstellar Bands in Y and J Bands. I. Newly Identified Bands

Kobayashi

Kawakita

Takenaka

et al. 2022

ApJS

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We searched for diffuse interstellar bands (DIBs) in the 0.91 < λ < 1.33 μm region by analyzing the near-infrared (NIR) high-resolution (R = 20,000 and 28,000) spectra of 31 reddened early-type stars (0.04 < E(B − V) < 4.58) and an unreddened reference star. The spectra were collected using the WINERED spectrograph, which was mounted on the 1.3 m Araki telescope at Koyama Astronomical Observatory, Japan, in 2012–2016, and on the 3.58 m New Technology Telescope at La Silla Observatory, Chile, in 2017–2018. We detected 54 DIBs—25 of which are newly detected by this study—and eight DIB candidates. Using this updated list, the DIB distributions over a wide wavelength range, from optical to NIR, are investigated. The FWHM values of the NIR DIBs are found to be narrower than those of the optical DIBs, on average, which suggests that the DIBs at longer wavelengths tend to be caused by larger molecules. Assuming that the larger carriers are responsible for the DIBs at longer wavelengths, and have larger oscillator strengths, we found that the total column densities of the DIB carriers tend to decrease with increasing DIB wavelength. The candidate molecules and ions for the NIR DIBs are also discussed.

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Section: Discussionmentioning

confidence: 89%

Section: Detected and Candidate Dibsmentioning

confidence: 87%

mentioning

confidence: 81%

Section: Observational Biasesmentioning

confidence: 99%

“…The black squares show the DIBs detected in the literature(Joblin et al 1990;Foing & Ehrenfreund 1994;Groh et al 2007). The green diamonds show the DIBs detected inEbenbichler et al (2022). The gray and black circles show the DIBs in the range of 4000-9000 Å(Fan et al 2019) and the H-band DIBs(Cox et al 2014), respectively.…”

mentioning

confidence: 99%

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Survey of Near-infrared Diffuse Interstellar Bands in Y and J Bands. I. Newly Identified Bands

Kobayashi

Kawakita

Takenaka

et al. 2022

ApJS

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Iron Complexes as Potential Carriers of Diffuse Interstellar Bands: The Photodissociation Spectrum of Fe⁺(H₂O) at Optical Wavelengths

Juanes,

Jin,

Saragi

et al. 2024

J. Phys. Chem. A

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The fullerene ion C 60 + is the only carrier of diffuse interstellar bands (DIBs) identified so far. Transition-metal compounds feature electronic transitions in the visible and near-infrared regions, making them potential DIB carriers. Since iron is the most abundant transition metal in the cosmos, we here test this idea with Fe + (H 2 O). Laboratory spectra were obtained by photodissociation spectroscopy at 80 K. Spectra were modeled with the reflection principle. A high-resolution spectrum of the DIB standard star HD 183143 served as an observational reference. Two broad bands were observed from 4120 to 6800 Å. The 4120− 4800 Å band has sharp features emerging from the background, which have the width of DIBs but do not match the band positions of the reference spectrum. Calculations show that the spectrum arises from a d−d transition at the iron center. While no match was found for Fe + (H 2 O) with known DIBs, the observation of structured bands with line widths typical for DIBs shows that small molecules or molecular ions containing iron are promising candidates for DIB carriers.

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A high-resolution study of near-IR diffuse interstellar bands, search for small-scale structure, time variability, and stellar features

Smoker

Müller

Monreal-Ibero

et al. 2023

A&A

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Context. The diffuse interstellar bands (DIBs) are a set of hundreds of unidentified absorption features that appear almost ubiquitously throughout the interstellar medium. Most DIBs appear at optical wavelengths, but some are in the near-infrared. Aims. We aim to characterise near-infrared DIBs at high spectral resolving power towards multiple targets. Methods. We observed 76 early-type stars at a resolving power of 50 000 (velocity resolution ~6 km s−1) and signal-to-noise ratios of several hundreds using the CRyogenic high-resolution InfraRed Echelle Spectrograph (CRIRES). These data allow us to investigate the DIBs around 1318.1, 1527.4, 1561.1, 1565.1, 1567.0, 1574.4, and 1624.2 nm. We detected a total of six DIB features and 17 likely stellar features through comparisons with a model spectrum computed with CMFGEN. Additionally, we measured equivalent widths of the DIBs at 1318.1 and 1527.4 nm using observations with X-shooter towards ten very highly reddened (3.2 < E(B–V) < 6.5) Cepheid variable stars and towards four stars observed at low values of precipitable water vapour as well as by using other archive data. Results. We measured correlations (correlation coefficient r ~ 0.73–0.96, depending on the subsample used) between DIB equivalent width and reddening for the DIBs at 1318.1, 1561.1, 1565.1, and 1567.0 nm. Comparing the near-infrared DIBs with 50 of the strongest optical DIBs, we find correlations r > ~0.8 between the 1318, 1527, 1561, 1565, and 1567 nm and the optical DIBs 5705, 5780, 6203, 6283, and 6269 Å. The 5797 Å DIB is less well correlated with the near-infrared DIBs. The DIB at 9632.1 Å, which is likely C60+, is not well correlated with the 1318.1 nm DIB. Partial correlation coefficients using E(B-V) as the covariate were also determined. For stars earlier than B2, the 1318.1 nm DIB is affected by an emission line on its blue wing that is likely stellar in nature, although we cannot rule out an interstellar or circumstellar origin for this line caused by, for example, a DIB in emission. The 1318.1 nm DIB also has an extended red wing. The line is reasonably well fitted by two Gaussian components, although neither the component equivalent width (EW) ratios nor the separation between components are obviously correlated with such indicators as λλ5780/5797 and reddening. The EW at 1318 nm correlates with H I with EW(1318 nm)/E(B – V) decreasing with f(H2). Five pairs of stars within one arcmin of each other show very similar 1318.1 nm DIB profiles. Possible variation in the 1318.1 nm feature is seen between HD 145501 and HD 145502 (separated by 41 arcsec, equivalent to 7200 au) and HD 168607 and HD 168625 (separated by 67 arcsec, equivalent to 0.52 pc on the plane of the sky). Seventeen sightlines have repeat CRIRES observations separated by six to 14 months, and two sightlines have repeat X-shooter observations separated by 9.9 yr. No time variability was detected in the 1318.1 nm DIB in the CRIRES data nor in the 5780.5 Å, 5797.1 Å, 1318.1 nm, and 1527.4 nm DIBs. Tentative time variation is observed in the C60+ DIBs at 9577 and 9632 Å towards HD 183143, although it is very close to the noise level and requires confirmation. Conclusions. The Near Infrared (NIR) DIBs observed occur more in more UV-irradiated regions than the 5797 Å DIB allowing the study of heavily reddened sightlines. Future searches for time variability in DIBs will require either higher quality data, larger intervals between epochs, or both.

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CRIRES high-resolution near-infrared spectroscopy of diffuse interstellar band profiles

Cited by 18 publications

References 83 publications

Survey of Near-infrared Diffuse Interstellar Bands in Y and J Bands. I. Newly Identified Bands

Survey of Near-infrared Diffuse Interstellar Bands in Y and J Bands. I. Newly Identified Bands

Iron Complexes as Potential Carriers of Diffuse Interstellar Bands: The Photodissociation Spectrum of Fe⁺(H₂O) at Optical Wavelengths

A high-resolution study of near-IR diffuse interstellar bands, search for small-scale structure, time variability, and stellar features

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CRIRES high-resolution near-infrared spectroscopy of diffuse interstellar band profiles

Cited by 18 publications

References 83 publications

Survey of Near-infrared Diffuse Interstellar Bands in Y and J Bands. I. Newly Identified Bands

Survey of Near-infrared Diffuse Interstellar Bands in Y and J Bands. I. Newly Identified Bands

Iron Complexes as Potential Carriers of Diffuse Interstellar Bands: The Photodissociation Spectrum of Fe+(H2O) at Optical Wavelengths

A high-resolution study of near-IR diffuse interstellar bands, search for small-scale structure, time variability, and stellar features

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Resources

About

Iron Complexes as Potential Carriers of Diffuse Interstellar Bands: The Photodissociation Spectrum of Fe⁺(H₂O) at Optical Wavelengths