Mapping diffuse interstellar bands in the local ISM on small scales via MUSE 3D spectroscopy

Wendt, Martin; Husser, Tim-Oliver; Kamann, Sebastian; Monreal-Ibero, A.; Richter, Philipp; Brinchmann, Jarle; Weilbacher, Peter M.; Wisotzki, L.

doi:10.1051/0004-6361/201629816

Cited by 9 publications

(8 citation statements)

References 56 publications

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“…On the other hand we will investigate the dynamical properties of globular clusters. Upcoming publications are in the field of multiple populations (Husser et al submitted, Latour et al submitted, Kamann et al in preparation), the search for emission line objects (Göttgens et al 2019, and Göttgens et al, submitted), cluster dynamics like the overall rotation (Kamann et al 2018), and gas clouds in direction of the clusters (Wendt et al 2017). Since this survey represents the first blind spectroscopic survey of globular cluster cores, we expect many unforeseen discoveries.…”

Section: Observations and Data Reductionmentioning

confidence: 85%

A stellar census in globular clusters with MUSE: Binaries in NGC 3201

Giesers

Kamann

Dreizler

et al. 2019

A&A

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178

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We utilize multi-epoch MUSE spectroscopy to study binary stars in the core of the Galactic globular cluster NGC 3201. Our sample consists of 3553 stars with 54 883 spectra in total comprising 3200 main-sequence stars up to 4 magnitudes below the turn-off. Each star in our sample has between 3 and 63 (with a median of 14) reliable radial velocity measurements within five years of observations. We introduce a statistical method to determine the probability of a star showing radial velocity variations based on the whole inhomogeneous radial velocity sample. Using HST photometry and an advanced dynamical MOCCA simulation of this specific cluster we overcome observational biases that previous spectroscopic studies had to deal with. This allows us to infer a binary frequency in the MUSE FoV and enables us to deduce the underlying true binary frequency of (6.75 ± 0.72) % in NGC 3201. The comparison of the MUSE observations with the MOCCA simulation suggests a significant fraction of primordial binaries. We can also confirm a radial increase of the binary fraction towards the cluster centre due to mass segregation. We discovered that in the core of NGC 3201 at least (57.5 ± 7.9) % of blue straggler stars are in a binary system. For the first time in a study of globular clusters, we were able to fit Keplerian orbits to a significant sample of 95 binaries. We present the binary system properties of eleven blue straggler stars and the connection to SX Phoenicis-type stars. We show evidence that two blue straggler formation scenarios, the mass transfer in binary (or triple) star systems and the coalescence due to binary-binary interactions, are present in our data. We also describe the binary and spectroscopic properties of four sub-subgiant (or red straggler) stars. Furthermore, we discovered two new black hole candidates with minimum masses (M sin i) of (7.68 ± 0.50) M , (4.4 ± 2.8) M , and refine the minimum mass estimate on the already published black hole to (4.53 ± 0.21) M . These black holes are consistent with an extensive black hole subsystem hosted by NGC 3201.

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Section: Observations and Data Reductionmentioning

confidence: 85%

A stellar census in globular clusters with MUSE: Binaries in NGC 3201

Giesers

Kamann

Dreizler

et al. 2019

A&A

Self Cite

178

191

View full text Add to dashboard Cite

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“…We also eliminate the contribution of the interstellar medium (ISM) component of the sodium D (NaD) lines, assuming the stars of each population are equally distributed in the field of view. Although Wendt et al (2017) found that the strength of the NaD (and K i) ISM varies across the field of view in NGC 6397, the preliminary results for NGC 2808 do not show a strong spatial variation (Wendt et al, in preparation). We computed the EWs using a trapezoidal integral because most of the residuals are too coarsely sampled to fit them with a line profile.…”

Section: Equivalent Widths Measurementsmentioning

confidence: 97%

A stellar census in globular clusters with MUSE: multiple populations chemistry in NGC 2808

Latour

Husser

Giesers

et al. 2019

A&A

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Context. Galactic globular clusters (GCs) are now known to host multiple populations displaying particular abundance variations. The different populations within a GC can be well distinguished following their position in the pseudo two-colors diagrams, also referred to as "chromosome maps." These maps are constructed using optical and near-UV photometry available from the Hubble Space Telescope (HST) UV survey of GCs. However, the chemical tagging of the various populations in the chromosome maps is hampered by the fact that HST photometry and elemental abundances are both only available for a limited number of stars. Aims. The spectra collected as part of the MUSE survey of globular clusters provide a spectroscopic counterpart to the HST photometric catalogs covering the central regions of GCs. In this paper, we use the MUSE spectra of 1115 red giant branch (RGB) stars in NGC 2808 to characterize the abundance variations seen in the multiple populations of this cluster. Methods. We used the chromosome map of NGC 2808 to divide the RGB stars into their respective populations. We then combined the spectra of all stars belonging to a given population, resulting in one high signal-to-noise ratio spectrum representative of each population. Results. Variations in the spectral lines of O, Na, Mg, and Al are clearly detected among four of the populations. In order to quantify these variations, we measured equivalent width differences and created synthetic populations spectra that were used to determine abundance variations with respect to the primordial population of the cluster. Our results are in good agreement with the values expected from previous studies based on high-resolution spectroscopy. We do not see any significant variations in the spectral lines of Ca, K, and Ba. We also do not detect abundance variations among the stars belonging to the primordial population of NGC 2808. Conclusions. We demonstrate that in spite of their low resolution, the MUSE spectra can be used to investigate abundance variations in the context of multiple populations.

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“…The residuals can contain random noise, additional absorption from the interstellar medium (Wendt et al 2017), systematic errors of the model spectra (e.g. absorption lines that only exist in the models, see Fig.…”

Section: Residuals From Spectral Fittingmentioning

confidence: 99%

A stellar census in globular clusters with MUSE: A spectral catalogue of emission-line sources

Göttgens

Husser

Kamann

et al. 2019

A&A

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Aims. Globular clusters produce many exotic stars due to a much higher frequency of dynamical interactions in their dense stellar environments. Some of these objects were observed together with several hundred thousands other stars in our MUSE survey of 26 Galactic globular clusters. Assuming that at least a few exotic stars have exotic spectra, that means spectra that contain emission lines, we can use this large spectroscopic data set of over a million stellar spectra as a blind survey to detect stellar exotica in globular clusters. Methods. To detect emission lines in each spectrum, we model the expected shape of an emission line as a Gaussian curve. This template is used for matched filtering on the differences between each observed 1D spectrum and its fitted spectral model. The spectra with the most significant detections of Hα emission are checked visually and cross-matched with published catalogues. Results. We find 156 stars with Hα emission, including several known cataclysmic variables (CV) and two new CVs, pulsating variable stars, eclipsing binary stars, the optical counterpart of a known black hole, several probable sub-subgiants and red stragglers, and 21 background emission-line galaxies. We find possible optical counterparts to 39 X-ray sources, as we detect Hα emission in several spectra of stars that are close to known positions of Chandra X-ray sources. This spectral catalogue can be used to supplement existing or future X-ray or radio observations with spectra of potential optical counterparts to classify the sources.

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Mapping diffuse interstellar bands in the local ISM on small scales via MUSE 3D spectroscopy

Cited by 9 publications

References 56 publications

A stellar census in globular clusters with MUSE: Binaries in NGC 3201

A stellar census in globular clusters with MUSE: Binaries in NGC 3201

A stellar census in globular clusters with MUSE: multiple populations chemistry in NGC 2808

A stellar census in globular clusters with MUSE: A spectral catalogue of emission-line sources

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