Near-infrared diffuse interstellar bands in APOGEE telluric standard star spectra

Elyajouri, M.; Lallement, R.; Monreal-Ibero, A.; Capitanio, L.; Cox, L.

doi:10.1051/0004-6361/201630088

Cited by 27 publications

(36 citation statements)

References 70 publications

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“…In a recent principal component analysis, Ensor et al (2017) demonstrate the hierarchical behavior of optical DIBs with respect to the radiation field, extending to a large set of strong DIBs the well-known skin effect observed for the 5780-5797 Å pair. This is also in agreement with a recent analysis by Elyajouri et al (2017) for five of the DIBs in the 5770-6620 Å region. Interestingly, the redshifts observed by Krełowski et al (2015) are found for the two strong DIBs that are the most favored in high irradiation clouds, namely the 5780 and 6284 Å DIBs, while the less influenced 6196 Å DIB is slightly shifted.…”

Section: The 9632 å Dib Toward Hd 37022supporting

confidence: 93%

The EDIBLES survey II. The detectability of C₆₀⁺ bands

Lallement

Cox

Cami

et al. 2018

A&A

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Gas phase spectroscopic laboratory experiments for the buckminsterfullerene cation C + 60 have resulted in accurate rest wavelengths for five C + 60 transitions that have been compared with diffuse interstellar bands (DIBs) in the near infra-red. Detecting these in astronomical spectra is difficult because of the strong contamination of ground-based spectra by atmospheric water vapor, to the presence of weak and shallow stellar lines and/or blending with other weak DIBs. The detection of the two strong bands has been claimed by several teams, and the three additional and weaker bands have been detected in a few sources. Certain recent papers have argued against the identification of C + 60 based on spectral analyses claiming (i) a large variation in the ratio of the equivalent widths of the 9632 and 9577 Å bands, (ii) a large redshift of the 9632 Å band for the Orion star HD 37022, and (iii) the non-detection of the weaker 9428 Å DIB. Here we address these three points: (i) We show that the model stellar line correction for the 9632 Å DIB overestimates the difference between the strengths of the lines in giant and dwarf star spectra, casting doubts on the conclusions about the ratio variability. (ii) Using high quality stellar spectra from the ESO Diffuse Interstellar Bands Large Exploration Survey (EDIBLES), recorded with the ESO/Paranal Ultraviolet Echelle Spectrograph (UVES) in about the same atmospheric conditions, we find no wavelength shift in the 9632 Å band toward HD 37022. (iii) Using EDIBLES spectra and data from the Echelle SpectroPolarimetric Device for the Observation of Stars (ESPaDOnS) at CFHT we show that the presence of a weak 9428 Å band cannot be ruled out, even in the same observations that a previous study claimed it was not present.

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Section: The 9632 å Dib Toward Hd 37022supporting

confidence: 93%

The EDIBLES survey II. The detectability of C₆₀⁺ bands

Lallement

Cox

Cami

et al. 2018

A&A

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“…The strengths of different DIBs are known to vary among sightlines with differing physical and chemical properties, independent of the total amount of interstellar material (e.g., Krełowski & Walker 1987;Ehrenfreund & Jenniskens 1995;Cami et al 1997;Elyajouri et al 2017;Ensor et al 2017). The EW per unit reddening (EW/E B-V ) provides a measure of the relative strength of a given DIB.…”

Section: Discussionmentioning

confidence: 99%

Searching for Interstellar Using a New Method for High Signal-to-noise HST/STIS Spectroscopy

Cordiner

Cox

Lallement

et al. 2017

ApJL

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A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription. AbstractDue to recent advances in laboratory spectroscopy, the first optical detection of a very large molecule has been claimed in the diffuse interstellar medium (ISM): C 60 + (ionized Buckminsterfullerene). Confirming the presence of this molecule would have significant implications regarding the carbon budget and chemical complexity of the ISM. Here we present results from a new method for ultra-high signal-to-noise ratio (S/N) spectroscopy of background stars in the near-infrared (at wavelengths of 0.9-1 μm), using the Hubble Space Telescope (HST) Imaging Spectrograph (STIS) in a previously untested "STIS scan" mode. The use of HST provides the crucial benefit of eliminating the need for error-prone telluric-correction methods in the part of the spectrum where the C 60 + bands lie and where the terrestrial water vapor contamination is severe. Our STIS spectrum of the heavily reddened B0 supergiant star BD+63 1964 reaches an unprecedented S/N for this instrument (∼600-800), allowing the detection of the diffuse interstellar band (DIB) at 9577 Å attributed to C 60 + , as well as new DIBs in the near-IR.Unfortunately, the presence of overlapping stellar lines, and the unexpected weakness of the C 60 + bands in this sightline, prevents conclusive detection of the weaker C 60 + bands. A probable correlation between the 9577 Å DIB strength and interstellar radiation field is identified, which suggests that more strongly irradiated interstellar sightlines will provide the optimal targets for future C 60 + searches.

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“…Besides, different DIBs react in different ways to the UV radiation field (e.g. Krelowski et al 1992;Cami et al 1997;Cox & Spaans 2006;Vos et al 2011;Cordiner et al 2013;Elyajouri et al 2017) and seem to show small scale spatial variations (Wendt et al 2017;Monreal-Ibero et al 2015a;Cordiner et al 2013;van Loon et al 2009) and different levels of clumpiness (Kos 2017). …”

Section: Introductionmentioning

confidence: 99%

Diffuse interstellar bands λ5780 and λ5797 in the Antennae Galaxy as seen by MUSE

Monreal-Ibero

Weilbacher

Wendt

2018

A&A

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Context. Diffuse interstellar bands (DIBs) are faint spectral absorption features of unknown origin. Research on DIBs beyond the Local Group is very limited and will surely blossom in the era of the Extremely Large Telescopes. However, we can already start paving the way. One possibility that needs to be explored is the use of high-sensitivity integral field spectrographs. Aims. Our goals are twofold. First, we aim to derive reliable mapping of at least one DIB in a galaxy outside the Local Group. Second, we want to explore the relation between DIBs and other properties of the interstellar medium (ISM) in the galaxy. Methods. We use Multi Unit Spectroscopic Explorer (MUSE) data for the Antennae Galaxy, the closest major galaxy merger. High signal-to-noise spectra were created by co-adding the signal of many spatial elements with the Voronoi binning technique. The emission of the underlying stellar population was modelled and substracted with the STARLIGHT spectral synthesis code. Flux and equivalent width of the features of interest were measured by means of fitting to Gaussian functions. Results. To our knowledge, we have derived the first maps for the DIBs at λ5780 and λ5797 in galaxies outside the Local Group. The strongest of the two DIBs (at λ5780) was detected in an area of ∼ 0.6 , corresponding to a linear scale of ∼ 25 kpc 2 . This region was sampled using >200 out of ∼1200 independent lines of sight. The DIB λ5797 was detected in >100 independent lines of sight. Both DIBs are associated with a region of high emission in the H i 21 cm line, implying a connection between atomic gas and DIBs, as the correlations in the Milky Way also suggest. Conversely, there is mild spatial association between the two DIBs and the molecular gas, in agreement with results for our Galaxy that indicate a lack of correlation between DIBs and molecular gas. The overall structures for the DIB strength distribution and extinction are comparable. Within the system, the λ5780 DIB clearly correlates with the extinction, and both DIBs follow the relationship between equivalent width and reddening when data for several galaxies are considered. This relationship is tighter when comparing only with galaxies with metallicities close to solar. Unidentified infrared emission bands (UIBs, likely caused by polycyclic aromatic hydrocarbons (PAHs)) and the λ5780 and λ5797 DIBs show similar but not identical spatial distributions. We attribute the differences to extinction effects without necessarily implying a radically different nature of the respective carriers. Conclusions. The results illustrate the enormous potential of integral field spectrographs for extragalactic DIB research.

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Near-infrared diffuse interstellar bands in APOGEE telluric standard star spectra

Cited by 27 publications

References 70 publications

The EDIBLES survey II. The detectability of C₆₀⁺ bands

The EDIBLES survey II. The detectability of C₆₀⁺ bands

Searching for Interstellar Using a New Method for High Signal-to-noise HST/STIS Spectroscopy

Diffuse interstellar bands λ5780 and λ5797 in the Antennae Galaxy as seen by MUSE

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Near-infrared diffuse interstellar bands in APOGEE telluric standard star spectra

Cited by 27 publications

References 70 publications

The EDIBLES survey II. The detectability of C60+ bands

The EDIBLES survey II. The detectability of C60+ bands

Searching for Interstellar Using a New Method for High Signal-to-noise HST/STIS Spectroscopy

Diffuse interstellar bands λ5780 and λ5797 in the Antennae Galaxy as seen by MUSE

Contact Info

Product

Resources

About

The EDIBLES survey II. The detectability of C₆₀⁺ bands

The EDIBLES survey II. The detectability of C₆₀⁺ bands