TY - JOUR A1 - Giesers, Benjamin David A1 - Kamann, Sebastian A1 - Dreizler, Stefan A1 - Husser, Tim-Oliver A1 - Askar, Abbas A1 - Göttgens, Fabian A1 - Brinchmann, Jarle A1 - Latour, Marilyn A1 - Weilbacher, Peter Michael A1 - Wendt, Martin A1 - Roth, Martin M. T1 - A stellar census in globular clusters with MUSE: Binaries in NGC 3201 JF - Astronomy and astrophysics : an international weekly journal N2 - We utilise 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 field of view 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 large portion of primordial binaries. We can also confirm a radial increase in 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-circle dot, (4.4 +/- 2.8)M-circle dot, and refine the minimum mass estimate on the already published black hole to (4.53 +/- 0.21)M-circle dot, These black holes are consistent with an extensive black hole subsystem hosted by NGC 3201. KW - binaries: general KW - blue stragglers KW - stars: black holes KW - techniques: radial velocities KW - techniques: imaging spectroscopy KW - globular clusters: individual: NGC 3201 Y1 - 2019 U6 - https://doi.org/10.1051/0004-6361/201936203 SN - 0004-6361 SN - 1432-0746 VL - 632 PB - EDP Sciences CY - Les Ulis ER - TY - JOUR A1 - Göttgens, Fabian A1 - Weilbacher, Peter Michael A1 - Roth, Martin M. A1 - Dreizler, Stefan A1 - Giesers, Benjamin A1 - Husser, Tim-Oliver A1 - Kamann, Sebastian A1 - Brinchmann, Jarle A1 - Kollatschny, Wolfram A1 - Monreal-Ibero, Ana A1 - Schmidt, Kasper Borello A1 - Wendt, Martin A1 - Wisotzki, Lutz A1 - Bacon, Roland T1 - Discovery of an old nova remnant in the Galactic globular cluster M 22 JF - Astronomy and astrophysics : an international weekly journal N2 - A nova is a cataclysmic event on the surface of a white dwarf in a binary system that increases the overall brightness by several orders of magnitude. Although binary systems with a white dwarf are expected to be overabundant in globular clusters compared with in the Galaxy, only two novae from Galactic globular clusters have been observed. We present the discovery of an emission nebula in the Galactic globular cluster M 22 (NGC 6656) in observations made with the integral-field spectrograph MUSE. We extracted the spectrum of the nebula and used the radial velocity determined from the emission lines to confirm that the nebula is part of NGC 6656. Emission-line ratios were used to determine the electron temperature and density. It is estimated to have a mass of 1-17 x 10(-5) M-circle dot. This mass and the emission-line ratios indicate that the nebula is a nova remnant. Its position coincides with the reported location of a "guest star", an ancient Chinese term for transients, observed in May 48 BCE. With this discovery, this nova may be one of the oldest confirmed extra-solar events recorded in human history. KW - globular clusters: individual: NGC 6656 KW - novae, cataclysmic variables KW - techniques: imaging spectroscopy Y1 - 2019 U6 - https://doi.org/10.1051/0004-6361/201935221 SN - 1432-0746 VL - 626 PB - EDP Sciences CY - Les Ulis ER - TY - JOUR A1 - Göttgens, Fabian A1 - Husser, Tim-Oliver A1 - Kamann, Sebastian A1 - Dreizler, Stefan A1 - Giesers, Benjamin A1 - Kollatschny, Wolfram A1 - Weilbacher, Peter Michael A1 - Roth, Martin M. A1 - Wendt, Martin T1 - A stellar census in globular clusters with MUSE: A spectral catalogue of emission-line sources JF - Astronomy and astrophysics : an international weekly journal N2 - 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 thousand other stars in our MUSE survey of 26 Galactic globular clusters. Assuming that at least a few exotic stars have exotic spectra (i.e. 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 modelled the expected shape of an emission line as a Gaussian curve. This template was used for matched filtering on the di fferences between each observed 1D spectrum and its fitted spectral model. The spectra with the most significant detections of H alpha emission are checked visually and cross-matched with published catalogues. Results. We find 156 stars with H alpha 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 detected H alpha 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. KW - globular clusters: general KW - stars: emission-line, Be KW - novae KW - cataclysmic variables KW - catalogs KW - techniques: imaging spectroscopy Y1 - 2019 U6 - https://doi.org/10.1051/0004-6361/201936485 SN - 0004-6361 SN - 1432-0746 VL - 631 PB - EDP Sciences CY - Les Ulis ER - TY - JOUR A1 - Weilbacher, Peter Michael A1 - Monreal-Ibero, Ana A1 - Verhamme, Anne A1 - Sandin, Christer A1 - Steinmetz, Matthias A1 - Kollatschny, Wolfram A1 - Krajnovic, Davor A1 - Kamann, Sebastian A1 - Roth, Martin M. A1 - Erroz-Ferrer, Santiago A1 - Marino, Raffaella Anna A1 - Maseda, Michael V. A1 - Wendt, Martin A1 - Bacon, Roland A1 - Dreizler, Stefan A1 - Richard, Johan A1 - Wisotzki, Lutz T1 - Lyman-continuum leakage as dominant source of diffuse ionized gas in the Antennae galaxy JF - Astronomy and astrophysics : an international weekly journal N2 - The Antennae galaxy (NGC 4038/39) is the closest major interacting galaxy system and is therefore often studied as a merger prototype. We present the first comprehensive integral field spectroscopic dataset of this system, observed with the MUSE instrument at the ESO VLT. We cover the two regions in this system which exhibit recent star formation: the central galaxy interaction and a region near the tip of the southern tidal tail. In these fields, we detect H II regions and diffuse ionized gas to unprecedented depth. About 15% of the ionized gas was undetected by previous observing campaigns. This newly detected faint ionized gas is visible everywhere around the central merger, and shows filamentary structure. We estimate diffuse gas fractions of about 60% in the central field and 10% in the southern region. We are able to show that the southern region contains a significantly different population of H II regions, showing fainter luminosities. By comparing H II region luminosities with the HST catalog of young star clusters in the central field, we estimate that there is enough Lyman-continuum leakage in the merger to explain the amount of diffuse ionized gas that we detect. We compare the Lyman-continuum escape fraction of each H II region against emission line ratios that are sensitive to the ionization parameter. While we find no systematic trend between these properties, the most extreme line ratios seem to be strong indicators of density bounded ionization. Extrapolating the Lyman-continuum escape fractions to the southern region, we conclude that simply from the comparison of the young stellar populations to the ionized gas there is no need to invoke other ionization mechanisms than Lyman-continuum leaking H II regions for the diffuse ionized gas in the Antennae. KW - galaxies: interactions KW - galaxies: individual: NGC 4038, NGC 4039 KW - galaxies: ISM KW - ISM: structure KW - H II regions Y1 - 2018 U6 - https://doi.org/10.1051/0004-6361/201731669 SN - 1432-0746 VL - 611 PB - EDP Sciences CY - Les Ulis ER - TY - JOUR A1 - Campos, Fabiola A1 - Pelisoli, Ingrid Domingos A1 - Kamann, Sebastian A1 - Husser, T. -O. A1 - Dreizler, S. A1 - Bellini, A. A1 - Robinson, E. L. A1 - Nardiello, Domenico A1 - Piotto, G. A1 - Kepler, S. O. A1 - Istrate, A. G. A1 - Winget, D. E. A1 - Montgomery, M. H. A1 - Dotter, A. T1 - Outliers BT - multicolour photometry guiding the search for evolved binary systems in the globular cluster 47 Tucanae JF - Monthly notices of the Royal Astronomical Society N2 - We use Hubble Space Telescope multicolour photometry of the globular cluster 47 Tucanae to uncover a population of 24 objects with no previous classification that are outliers from the single-star model tracks in the colour-magnitude diagram and yet are likely cluster members. By comparing those sources with evolutionary models and X-ray source catalogues, we were able to show that the majority of those sources are likely binary systems that do not have any X-ray source detected nearby, most possibly formed by a white dwarf and a main-sequence star and a small number of possible double-degenerate systems. KW - binaries: general KW - Hertzsprung-Russell and colour-magnitude diagrams KW - white dwarfs KW - globular clusters: individual: 47 Tuc Y1 - 2018 U6 - https://doi.org/10.1093/mnras/sty2591 SN - 0035-8711 SN - 1365-2966 VL - 481 IS - 4 SP - 4397 EP - 4409 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Kamann, Sebastian A1 - Husser, T. -O. A1 - Dreizler, S. A1 - Emsellem, E. A1 - Weilbacher, Peter Michael A1 - Martens, S. A1 - Bacon, R. A1 - den Brok, M. A1 - Giesers, B. A1 - Krajnovic, Davor A1 - Roth, Martin M. A1 - Wendt, Martin A1 - Wisotzki, Lutz T1 - A stellar census in globular clusters with MUSE BT - the contribution of rotation to cluster dynamics studied with 200 000 stars JF - Monthly notices of the Royal Astronomical Society N2 - This is the first of a series of papers presenting the results from our survey of 25 Galactic globular clusters with the MUSE integral-field spectrograph. In combination with our dedicated algorithm for source deblending, MUSE provides unique multiplex capabilities in crowded stellar fields and allows us to acquire samples of up to 20 000 stars within the half-light radius of each cluster. The present paper focuses on the analysis of the internal dynamics of 22 out of the 25 clusters, using about 500 000 spectra of 200 000 individual stars. Thanks to the large stellar samples per cluster, we are able to perform a detailed analysis of the central rotation and dispersion fields using both radial profiles and two-dimensional maps. The velocity dispersion profiles we derive show a good general agreement with existing radial velocity studies but typically reach closer to the cluster centres. By comparison with proper motion data, we derive or update the dynamical distance estimates to 14 clusters. Compared to previous dynamical distance estimates for 47 Tuc, our value is in much better agreement with other methods. We further find significant (>3 sigma) rotation in the majority (13/22) of our clusters. Our analysis seems to confirm earlier findings of a link between rotation and the ellipticities of globular clusters. In addition, we find a correlation between the strengths of internal rotation and the relaxation times of the clusters, suggesting that the central rotation fields are relics of the cluster formation that are gradually dissipated via two-body relaxation. KW - techniques: imaging spectroscopy KW - stars: kinematics and dynamics KW - globular clusters: general Y1 - 2017 U6 - https://doi.org/10.1093/mnras/stx2719 SN - 0035-8711 SN - 1365-2966 VL - 473 IS - 4 SP - 5591 EP - 5616 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Wendt, Martin A1 - Husser, Tim-Oliver A1 - Kamann, Sebastian A1 - Monreal-Ibero, Ana A1 - Richter, Philipp A1 - Brinchmann, Jarle A1 - Dreizler, Stefan A1 - Weilbacher, Peter Michael A1 - Wisotzki, Lutz T1 - Mapping diffuse interstellar bands in the local ISM on small scales via MUSE 3D spectroscopy A pilot study based on globular cluster NGC 6397 JF - Astronomy and astrophysics : an international weekly journal N2 - Context. We map the interstellar medium (ISM) including the diffuse interstellar bands (DIBs) in absorption toward the globular cluster NGC6397 using VLT/MUSE. Assuming the absorbers are located at the rim of the Local Bubble we trace structures on the order of mpc (milliparsec, a few thousand AU). Aims. We aimed to demonstrate the feasibility to map variations of DIBs on small scales with MUSE. The sightlines defined by binned stellar spectra are separated by only a few arcseconds and we probe the absorption within a physically connected region. Methods. This analysis utilized the fitting residuals of individual stellar spectra of NGC6397 member stars and analyzed lines from neutral species and several DIBs in Voronoi-binned composite spectra with high signal-to-noise ratio (S/N). Results. This pilot study demonstrates the power of MUSE for mapping the local ISM on very small scales which provides a new window for ISM observations. We detect small scale variations in Na-I and K-I as well as in several DIBs within few arcseconds, or mpc with regard to the Local Bubble. We verify the suitability of the MUSE 3D spectrograph for such measurements and gain new insights by probing a single physical absorber with multiple sight lines. KW - techniques: imaging spectroscopy KW - globular clusters: individual: NGC 6397 KW - dust, extinction KW - ISM: structure KW - ISM: lines and bands Y1 - 2017 U6 - https://doi.org/10.1051/0004-6361/201629816 SN - 1432-0746 VL - 607 PB - EDP Sciences CY - Les Ulis ER - TY - JOUR A1 - Husser, Tim-Oliver A1 - Kamann, Sebastian A1 - Dreizler, Stefan A1 - Wendt, Martin A1 - Wulff, Nina A1 - Bacon, Roland A1 - Wisotzki, Lutz A1 - Brinchmann, Jarle A1 - Weilbacher, Peter Michael A1 - Roth, Martin M. A1 - Monreal-Ibero, Ana T1 - MUSE crowded field 3D spectroscopy of over 12 000 stars in the globular cluster NGC 6397 I. The first comprehensive HRD of a globular cluster JF - Nucleic acids research N2 - Aims. We demonstrate the high multiplex advantage of crowded field 3D spectroscopy with the new integral field spectrograph MUSE by means of a spectroscopic analysis of more than 12 000 individual stars in the globular cluster NGC 6397. Methods. The stars are deblended with a point spread function fitting technique, using a photometric reference catalogue from HST as prior, including relative positions and brightnesses. This catalogue is also used for a first analysis of the extracted spectra, followed by an automatic in-depth analysis via a full-spectrum fitting method based on a large grid of PHOENIX spectra. Results. We analysed the largest sample so far available for a single globular cluster of 18 932 spectra from 12 307 stars in NGC 6397. We derived a mean radial velocity of v(rad) = 17.84 +/- 0.07 km s(-1) and a mean metallicity of [Fe/H] = -2.120 +/- 0.002, with the latter seemingly varying with temperature for stars on the red giant branch (RGB). We determine Teff and [Fe/H] from the spectra, and log g from HST photometry. This is the first very comprehensive Hertzsprung-Russell diagram (HRD) for a globular cluster based on the analysis of several thousands of stellar spectra, ranging from the main sequence to the tip of the RGB. Furthermore, two interesting objects were identified; one is a post-AGB star and the other is a possible millisecond-pulsar companion. KW - methods: data analysis KW - techniques: imaging spectroscopy KW - planets and satellites: fundamental parameters KW - stars: atmospheres KW - pulsars: general KW - globular clusters: individual: NGC 6397 Y1 - 2016 U6 - https://doi.org/10.1051/0004-6361/201526949 SN - 1432-0746 VL - 588 PB - EDP Sciences CY - Les Ulis ER - TY - JOUR A1 - Monreal-Ibero, Ana A1 - Weilbacher, Peter Michael A1 - Wendt, Martin A1 - Selman, Fernando A1 - Lallement, Rosine A1 - Brinchmann, Jarle A1 - Kamann, Sebastian A1 - Sandin, Christer T1 - Towards DIB mapping in galaxies beyond 100 Mpc A radial profile of the lambda 5780.5 diffuse interstellar band in AM1353-272 B JF - Astronomy and astrophysics : an international weekly journal N2 - Context. Diffuse interstellar bands (DIBs) are non-stellar weak absorption features of unknown origin found in the spectra of stars viewed through one or several clouds of the interstellar medium (ISM). Research of DIBs outside the Milky Way is currently very limited. In particular, spatially resolved investigations of DIBs outside of the Local Group are, to our knowledge, inexistent. Aims. In this contribution, we explore the capability of the high-sensitivity integral field spectrograph, MUSE, as a tool for mapping diffuse interstellar bands at distances larger than 100 Mpc. Methods. We used MUSE commissioning data for AM1353-272 B, the member with the highest extinction of the Dentist's Chair, an interacting system of two spiral galaxies. High signal-to-noise spectra were created by co-adding the signal of many spatial elements distributed in a geometry of concentric elliptical half-rings. Results. We derived decreasing radial profiles for the equivalent width of the lambda 5780.5 DIB both in the receding and approaching side of the companion galaxy up to distances of similar to 4.6 kpc from the centre of the galaxy. The interstellar extinction as derived from the Ha/H beta line ratio displays a similar trend, with decreasing values towards the external parts. This translates into an intrinsic correlation between the strength of the DIB and the extinction within AM1353-272 B, consistent with the currently existing global trend between these quantities when using measurements for Galactic and extragalactic sightlines. Conclusions. It seems feasible to map the DIB strength in the Local Universe, which has up to now only been performed for the Milky Way. This offers a new approach to studying the relationship between DIBs and other characteristics and species of the ISM in addition to using galaxies in the Local Group or sightlines towards very bright targets outside the Local Group. KW - dust, extinction KW - ISM: lines and bands KW - galaxies: ISM KW - galaxies: individual: AM1353-272 B Y1 - 2015 U6 - https://doi.org/10.1051/0004-6361/201525854 SN - 0004-6361 SN - 1432-0746 VL - 576 PB - EDP Sciences CY - Les Ulis ER - TY - JOUR A1 - Weilbacher, Peter Michael A1 - Monreal-Ibero, Ana A1 - Kollatschny, Wolfram A1 - Ginsburg, Adam A1 - McLeod, Anna F. A1 - Kamann, Sebastian A1 - Sandin, Christer A1 - Palsa, Ralf A1 - Wisotzki, Lutz A1 - Bacon, Roland A1 - Selman, Fernando A1 - Brinchmann, Jarle A1 - Caruana, Joseph A1 - Kelz, Andreas A1 - Martinsson, Thomas A1 - Pecontal-Rousset, Arlette A1 - Richard, Johan A1 - Wendt, Martin T1 - A MUSE map of the central Orion Nebula (M 42) JF - Astronomy and astrophysics : an international weekly journal N2 - We present a new integral field spectroscopic dataset of the central part of the Orion Nebula (M 42), observed with the MUSE instrument at the ESO VLT. We reduced the data with the public MUSE pipeline. The output products are two FITS cubes with a spatial size of similar to 5'9 x 4'9 (corresponding to similar to 0.76 x 0.63 pc(2)) and a contiguous wavelength coverage of 4595 ... 9366 angstrom, spatially sampled at 0 ''.2. We provide two versions with a sampling of 1.25 angstrom and 0.85 angstrom in dispersion direction. Together with variance cubes these files have a size of 75 and 110 GiB on disk. They are the largest integral field mosaics to date in terms of information content. We make them available for use in the community. To validate this dataset, we compare world coordinates, reconstructed magnitudes, velocities, and absolute and relative emission line fluxes to the literature values and find excellent agreement. We derive a 2D map of extinction and present de-reddened flux maps of several individual emission lines and of diagnostic line ratios. We estimate physical properties of the Orion Nebula, using the emission line ratios [N II] and [S III] (for the electron temperature T-e) and [S II] and [Cl III] (for the electron density N-e), and show 2D images of the velocity measured from several bright emission lines. KW - H II regions KW - ISM: individual objects: M 42 KW - open clusters and associations: individual: Trapezium cluster Y1 - 2015 U6 - https://doi.org/10.1051/0004-6361/201526529 SN - 1432-0746 VL - 582 PB - EDP Sciences CY - Les Ulis ER -