TY - JOUR A1 - Almeida, Leonardo A. A1 - Sana, H. A1 - Taylor, W. A1 - Barbá, Rodolfo A1 - Bonanos, Alceste Z. A1 - Crowther, Paul A1 - Damineli, Augusto A1 - de Koter, A. A1 - de Mink, Selma E. A1 - Evans, C. J. A1 - Gieles, Mark A1 - Grin, Nathan J. A1 - Hénault-Brunet, V. A1 - Langer, Norbert A1 - Lennon, D. A1 - Lockwood, Sean A1 - Maíz Apellániz, Jesús A1 - Moffat, A. F. J. A1 - Neijssel, C. A1 - Norman, C. A1 - Ramírez-Agudelo, O. H. A1 - Richardson, N. D. A1 - Schootemeijer, Abel A1 - Shenar, Tomer A1 - Soszyński, Igor A1 - Tramper, Frank A1 - Vink, J. S. T1 - The tarantula massive binary monitoring BT - I. Observational campaign and OB-type spectroscopic binaries JF - Astronomy and astrophysics : an international weekly journal N2 - Context: Massive binaries play a crucial role in the Universe. Knowing the distributions of their orbital parameters is important for a wide range of topics from stellar feedback to binary evolution channels and from the distribution of supernova types to gravitational wave progenitors, yet no direct measurements exist outside the Milky Way. Aims: The Tarantula Massive Binary Monitoring project was designed to help fill this gap by obtaining multi-epoch radial velocity (RV) monitoring of 102 massive binaries in the 30 Doradus region. Methods: In this paper we analyze 32 FLAMES/GIRAFFE observations of 93 O- and 7 B-type binaries. We performed a Fourier analysis and obtained orbital solutions for 82 systems: 51 single-lined (SB1) and 31 double-lined (SB2) spectroscopic binaries. Results: Overall, the binary fraction and orbital properties across the 30 Doradus region are found to be similar to existing Galactic samples. This indicates that within these domains environmental effects are of second order in shaping the properties of massive binary systems. A small difference is found in the distribution of orbital periods, which is slightly flatter (in log space) in 30 Doradus than in the Galaxy, although this may be compatible within error estimates and differences in the fitting methodology. Also, orbital periods in 30 Doradus can be as short as 1.1 d, somewhat shorter than seen in Galactic samples. Equal mass binaries (q> 0.95) in 30 Doradus are all found outside NGC 2070, the central association that surrounds R136a, the very young and massive cluster at 30 Doradus’s core. Most of the differences, albeit small, are compatible with expectations from binary evolution. One outstanding exception, however, is the fact that earlier spectral types (O2–O7) tend to have shorter orbital periods than later spectral types (O9.2–O9.7). Conclusions: Our results point to a relative universality of the incidence rate of massive binaries and their orbital properties in the metallicity range from solar (Z⊙) to about half solar. This provides the first direct constraints on massive binary properties in massive star-forming galaxies at the Universe’s peak of star formation at redshifts z ~ 1 to 2 which are estimated to have Z ~ 0.5 Z⊙. KW - stars: early-type KW - stars: massive KW - binaries: spectroscopic KW - binaries: close Y1 - 2017 U6 - https://doi.org/10.1051/0004-6361/201629844 SN - 1432-0746 VL - 598 PB - EDP Sciences CY - Les Ulis ER - TY - JOUR A1 - Shenar, Tomer A1 - Richardson, N. D. A1 - Sablowski, Daniel P. A1 - Hainich, Rainer A1 - Sana, H. A1 - Moffat, A. F. J. A1 - Todt, Helge Tobias A1 - Hamann, Wolf-Rainer A1 - Oskinova, Lidia M. A1 - Sander, Andreas Alexander Christoph A1 - Tramper, Frank A1 - Langer, Norbert A1 - Bonanos, Alceste Z. A1 - de Mink, Selma E. A1 - Gräfener, G. A1 - Crowther, Paul A1 - Vink, J. S. A1 - Almeida, Leonardo A. A1 - de Koter, A. A1 - Barbá, Rodolfo A1 - Herrero, A. A1 - Ulaczyk, Krzysztof T1 - The tarantula massive binary monitoring BT - II. First SB2 orbital and spectroscopic analysis for the Wolf-Rayet binary R145 JF - Astronomy and astrophysics : an international weekly journal N2 - We present the first SB2 orbital solution and disentanglement of the massive Wolf-Rayet binary R145 (P = 159 d) located in the Large Magellanic Cloud. The primary was claimed to have a stellar mass greater than 300 M-circle dot, making it a candidate for being the most massive star known to date. While the primary is a known late-type, H-rich Wolf-Rayet star (WN6h), the secondary has so far not been unambiguously detected. Using moderate-resolution spectra, we are able to derive accurate radial velocities for both components. By performing simultaneous orbital and polarimetric analyses, we derive the complete set of orbital parameters, including the inclination. The spectra are disentangled and spectroscopically analyzed, and an analysis of the wind-wind collision zone is conducted. The disentangled spectra and our models are consistent with a WN6h type for the primary and suggest that the secondary is an O3.5 If*/WN7 type star. We derive a high eccentricity of e = 0 : 78 and minimum masses of M-1 sin(3) i approximate to M-2 sin(3) i = 13 +/- 2 M-circle dot, with q = M-2/M-1 = 1.01 +/- 0.07. An analysis of emission excess stemming from a wind-wind collision yields an inclination similar to that obtained from polarimetry (i = 39 +/- 6 degrees). Our analysis thus implies M-1 = 53(-20)(+40) and M2 = 54(-20)(+40) M-circle dot, excluding M-1 > 300 M-circle dot. A detailed comparison with evolution tracks calculated for single and binary stars together with the high eccentricity suggests that the components of the system underwent quasi-homogeneous evolution and avoided mass-transfer. This scenario would suggest current masses of approximate to 80 M-circle dot and initial masses of M-i,M-1 approximate to 10(5) and M-i,M-2 approximate to 90 M-circle dot, consistent with the upper limits of our derived orbital masses, and would imply an age of approximate to 2.2 Myr. KW - binaries: spectroscopic KW - stars: Wolf-Rayet KW - stars: massive KW - Magellanic Clouds KW - stars: individual: R 145 KW - stars: atmospheres Y1 - 2017 U6 - https://doi.org/10.1051/0004-6361/201629621 SN - 1432-0746 VL - 598 PB - EDP Sciences CY - Les Ulis ER - TY - JOUR A1 - Petreska, Irina A1 - de Castro, Antonio S. M. A1 - Sandev, Trifce A1 - Lenzi, Ervin K. T1 - The time-dependent Schrödinger equation in non-integer dimensions for constrained quantum motion JF - Modern physics letters : A, Particles and fields, gravitation, cosmology, nuclear physics N2 - We propose a theoretical model, based on a generalized Schroedinger equation, to study the behavior of a constrained quantum system in non-integer, lower than two-dimensional space. The non-integer dimensional space is formed as a product space X x Y, comprising x-coordinate with a Hausdorff measure of dimension alpha(1) = D -1 (1 < D < 2) and y-coordinate with the Lebesgue measure of dimension of length (alpha(2) = 1). Geometric constraints are set at y = 0. Two different approaches to find the Green's function are employed, both giving the same form in terms of the Fox H-function. For D = 2, the solution for two-dimensional quantum motion on a comb is recovered. (C) 2020 Elsevier B.V. All rights reserved. KW - Schrödinger equation KW - non-integer dimension KW - Green's function KW - Bessel functions KW - Fox H-function Y1 - 2020 U6 - https://doi.org/10.1016/j.physleta.2020.126866 SN - 0375-9601 SN - 1873-2429 VL - 384 IS - 34 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Klein, Markus A1 - Rosenberger, Elke T1 - The tunneling effect for Schrödinger operators on a vector bundle JF - Analysis and mathematical physics N2 - In the semiclassical limit (h) over bar -> 0, we analyze a class of self-adjoint Schrodinger operators H-(h) over bar = (h) over bar L-2 + (h) over barW + V center dot id(E) acting on sections of a vector bundle E over an oriented Riemannian manifold M where L is a Laplace type operator, W is an endomorphism field and the potential energy V has non-degenerate minima at a finite number of points m(1),... m(r) is an element of M, called potential wells. Using quasimodes of WKB-type near m(j) for eigenfunctions associated with the low lying eigenvalues of H-(h) over bar, we analyze the tunneling effect, i.e. the splitting between low lying eigenvalues, which e.g. arises in certain symmetric configurations. Technically, we treat the coupling between different potential wells by an interaction matrix and we consider the case of a single minimal geodesic (with respect to the associated Agmon metric) connecting two potential wells and the case of a submanifold of minimal geodesics of dimension l + 1. This dimension l determines the polynomial prefactor for exponentially small eigenvalue splitting. KW - Laplace-type operator KW - Vector bundle KW - WKB-expansion KW - Quasimodes KW - Tunneling KW - Spectral gap KW - Complete asymptotics Y1 - 2021 U6 - https://doi.org/10.1007/s13324-021-00485-5 SN - 1664-2368 SN - 1664-235X VL - 11 IS - 2 PB - Springer International Publishing AG CY - Cham (ZG) ER - TY - JOUR A1 - Sun, Ning-Chen A1 - de Grijs, Richard A1 - Subramanian, Smitha A1 - Cioni, Maria-Rosa L. A1 - Rubele, Stefano A1 - Bekki, Kenji A1 - Ivanov, Valentin D. A1 - Piatti, Andrés E. A1 - Ripepi, Vincenzo T1 - The VMC Survey. XXII. Hierarchical star formation in the 30 Doradus-N158-N159-N160 star-forming complex JF - The astrophysical journal : an international review of spectroscopy and astronomical physics N2 - We study the hierarchical stellar structures in a similar to 1.5 deg(2) area covering the 30. Doradus-N158-N159-N160 starforming complex with the VISTA Survey of. Magellanic Clouds. Based on the young upper main-sequence stars, we find that the surface densities cover a wide range of values, from log(Sigma.pc(2))less than or similar to -2.0 to log(Sigma. pc(2)) greater than or similar to 0.0. Their distributions are highly non-uniform, showing groups that frequently have subgroups inside. The sizes of the stellar groups do not exhibit characteristic values, and range continuously from several parsecs to more than 100. pc; the cumulative size distribution can be well described by a single power law, with the power-law index indicating a projected fractal dimension D-2 = 1.6 +/- 0.3. We suggest that the phenomena revealed here support a scenario of hierarchical star formation. Comparisons with other star-forming regions and galaxies are also discussed. KW - galaxies: clusters: general KW - infrared: stars KW - Magellanic Clouds KW - stars: formation Y1 - 2017 U6 - https://doi.org/10.3847/1538-4357/835/2/171 SN - 0004-637X SN - 1538-4357 VL - 835 IS - 2 PB - Institute of Physics Publ. CY - Bristol ER - TY - JOUR A1 - Shenar, Tomer A1 - Sablowski, D. P. A1 - Hainich, Rainer A1 - Todt, Helge Tobias A1 - Moffat, Anthony F. J. A1 - Oskinova, Lidia M. A1 - Ramachandran, Varsha A1 - Sana, Hugues A1 - Sander, Andreas Alexander Christoph A1 - Schnurr, O. A1 - St-Louis, N. A1 - Vanbeveren, D. A1 - Gotberg, Y. A1 - Hamann, Wolf-Rainer T1 - The Wolf-Rayet binaries of the nitrogen sequence in the Large Magellanic Cloud Spectroscopy, orbital analysis, formation, and evolution JF - Astronomy and astrophysics : an international weekly journal N2 - Context. Massive Wolf-Rayet (WR) stars dominate the radiative and mechanical energy budget of galaxies and probe a critical phase in the evolution of massive stars prior to core collapse. It is not known whether core He-burning WR stars (classical WR; cWR) form predominantly through wind stripping (w-WR) or binary stripping (b-WR). Whereas spectroscopy of WR binaries has so-far largely been avoided because of its complexity, our study focuses on the 44 WR binaries and binary candidates of the Large Magellanic Cloud (LMC; metallicity Z approximate to 0.5 Z(circle dot)), which were identified on the basis of radial velocity variations, composite spectra, or high X-ray luminosities. Aims. Relying on a diverse spectroscopic database, we aim to derive the physical and orbital parameters of our targets, confronting evolution models of evolved massive stars at subsolar metallicity and constraining the impact of binary interaction in forming these stars. Methods. Spectroscopy was performed using the Potsdam Wolf-Rayet (PoWR) code and cross-correlation techniques. Disentanglement was performed using the code Spectangular or the shift-and-add algorithm. Evolutionary status was interpreted using the Binary Population and Spectral Synthesis (BPASS) code, exploring binary interaction and chemically homogeneous evolution. Results. Among our sample, 28/44 objects show composite spectra and are analyzed as such. An additional five targets show periodically moving WR primaries but no detected companions (SB1); two (BAT99 99 and 112) are potential WR + compact-object candidates owing to their high X-ray luminosities. We cannot confirm the binary nature of the remaining 11 candidates. About two-thirds of the WN components in binaries are identified as cWR, and one-third as hydrogen-burning WR stars. We establish metallicity-dependent mass-loss recipes, which broadly agree with those recently derived for single WN stars, and in which so-called WN3/O3 stars are clear outliers. We estimate that 45 +/- 30% of the cWR stars in our sample have interacted with a companion via mass transfer. However, only approximate to 12 +/- 7% of the cWR stars in our sample naively appear to have formed purely owing to stripping via a companion (12% b-WR). Assuming that apparently single WR stars truly formed as single stars, this comprises approximate to 4% of the whole LMC WN population, which is about ten times less than expected. No obvious differences in the properties of single and binary WN stars, whose luminosities extend down to log L approximate to 5.2 [L-circle dot], are apparent. With the exception of a few systems (BAT99 19, 49, and 103), the equatorial rotational velocities of the OB-type companions are moderate (v(eq) less than or similar to 250 km s(-1)) and challenge standard formalisms of angular-momentum accretion. For most objects, chemically homogeneous evolution can be rejected for the secondary, but not for the WR progenitor. Conclusions. No obvious dichotomy in the locations of apparently single and binary WN stars on the Hertzsprung-Russell diagram is apparent. According to commonly used stellar evolution models (BPASS, Geneva), most apparently single WN stars could not have formed as single stars, implying that they were stripped by an undetected companion. Otherwise, it must follow that pre-WR mass-loss/mixing (e.g., during the red supergiant phase) are strongly underestimated in standard stellar evolution models. KW - stars: massive KW - stars: Wolf-Rayet KW - Magellanic Clouds KW - binaries: close KW - binaries: spectroscopic KW - stars: evolution Y1 - 2019 U6 - https://doi.org/10.1051/0004-6361/201935684 SN - 0004-6361 SN - 1432-0746 VL - 627 PB - EDP Sciences CY - Les Ulis ER - TY - JOUR A1 - Selsing, Jonatan A1 - Malesani, D. A1 - Goldoni, P. A1 - Fynbo, Johan A1 - Krühler, T. A1 - Antonelli, L. A. A1 - Arabsalmani, M. A1 - Bolmer, J. A1 - Cano, Z. A1 - Christensen, L. A1 - Covino, S. A1 - De Cia, A. A1 - de Ugarte Postigo, A. A1 - Flores, H. A1 - Fliis, M. A1 - Gomboc, A. A1 - Greiner, J. A1 - Groot, P. A1 - Hammer, F. A1 - Hartoog, O. E. A1 - Heintz, K. E. A1 - Hjorth, J. A1 - Jakobsson, P. A1 - Japelj, J. A1 - Kann, D. A. A1 - Kaper, L. A1 - Ledoux, C. A1 - Leloudas, G. A1 - Levan, A. J. A1 - Maiorano, E. A1 - Melandri, A. A1 - Milvang-Jensen, B. A1 - Palazzi, E. A1 - Palmerio, J. T. A1 - Perley, D. A. A1 - Pian, E. A1 - Piranomonte, S. A1 - Pugliese, G. A1 - Sanchez-Ramirez, R. A1 - Savaglio, S. A1 - Schady, P. A1 - Schulze, S. A1 - Sollerman, J. A1 - Sparre, Martin A1 - Tagliaferri, G. A1 - Tanvir, N. R. A1 - Thone, C. C. A1 - Vergani, S. D. A1 - Vreeswijk, P. A1 - Watson, D. A1 - Wiersema, K. A1 - Wijers, R. A1 - Xu, D. A1 - Zafar, T. T1 - The X-shooter GRB afterglow legacy sample (XS-GRB) JF - Astronomy and astrophysics : an international weekly journal N2 - In this work we present spectra of all gamma-ray burst (GRB) afterglows that have been promptly observed with the X-shooter spectrograph until 31/03/2017. In total, we have obtained spectroscopic observations of 103 individual GRBs observed within 48 hours of the GRB trigger. Redshifts have been measured for 97 per cent of these, covering a redshift range from 0.059 to 7.84. Based on a set of observational selection criteria that minimise biases with regards to intrinsic properties of the GRBs, the follow-up effort has been focused on producing a homogeneously selected sample of 93 afterglow spectra for GRBs discovered by the Swift satellite. We here provide a public release of all the reduced spectra, including continuum estimates and telluric absorption corrections. For completeness, we also provide reductions for the 18 late-time observations of the underlying host galaxies. We provide an assessment of the degree of completeness with respect to the parent GRB population, in terms of the X-ray properties of the bursts in the sample and find that the sample presented here is representative of the full Swift sample. We have constrained the fraction of dark bursts to be <28 per cent and confirm previous results that higher optical darkness is correlated with increased X-ray absorption. For the 42 bursts for which it is possible, we have provided a measurement of the neutral hydrogen column density, increasing the total number of published HI column density measurements by similar to 33 per cent. This dataset provides a unique resource to study the ISM across cosmic time, from the local progenitor surroundings to the intervening Universe. KW - gamma-ray burst: general KW - galaxies: high-redshift KW - ISM: general KW - techniques: spectroscopic KW - catalogs KW - galaxies: star formation Y1 - 2019 U6 - https://doi.org/10.1051/0004-6361/201832835 SN - 1432-0746 SN - 0004-6361 VL - 623 PB - EDP Sciences CY - Les Ulis ER - TY - JOUR A1 - Flores Suárez, Rosaura A1 - Mellinger, Axel A1 - Wegener, Michael A1 - Wirges, Werner A1 - Gerhard, Reimund A1 - Singh, Rajeev T1 - Thermal-pulse tomography of polarization distributions in a cylindrical geometry JF - IEEE transactions on dielectrics and electrical insulation N2 - Fast, three-dimensional polarization mapping in piezoelectric sensor cables was performed by means of the novel thermal-pulse tomography (TPT) technique with a lateral resolution of 200 mum. The active piezoelectric cable material (a copolymer of polyvinylidene fluoride with trifluoroethylene) was electrically poled with a point-to-cable corona discharge. A focused laser was employed to heat the opaque outer electrode, and the short-circuit current generated by the thermal pulse was used to obtain 3D polarization maps via the scale transformation method. The article describes the TPT technique as a fast non-destructive option for studying cylindrical geometries. Y1 - 2006 U6 - https://doi.org/10.1109/TDEI.2006.258210 SN - 1070-9878 VL - 13 IS - 5 SP - 1030 EP - 1035 PB - IEEE CY - Piscataway ER - TY - JOUR A1 - Henkel, Carsten T1 - Thermally excited quasiparticles in metals, dispersion forces, and the thermal anomaly JF - Modern physics letters : A, Particles and fields, gravitation, cosmology, nuclear physics N2 - We provide a brief review of the contribution of thermally excited carriers to dispersion forces. In a metal, these carriers generate charge and current fluctuations whose spectral frequencies are comparable to k(B)T/(h) over bar. They are very likely responsible for the "plasma vs. Drude" anomaly. KW - Dispersion force KW - quasi-particles Y1 - 2020 U6 - https://doi.org/10.1142/S021773232040009X SN - 0217-7323 SN - 1793-6632 VL - 35 IS - 3 PB - World Scientific CY - Singapore ER - TY - JOUR A1 - Abiuso, Paolo A1 - Holubec, Viktor A1 - Anders, Janet A1 - Ye, Zhuolin A1 - Cerisola, Federico A1 - Perarnau-Llobet, Marti T1 - Thermodynamics and optimal protocols of multidimensional quadratic Brownian systems JF - Journal of physics communications N2 - We characterize finite-time thermodynamic processes of multidimensional quadratic overdamped systems. Analytic expressions are provided for heat, work, and dissipation for any evolution of the system covariance matrix. The Bures-Wasserstein metric between covariance matrices naturally emerges as the local quantifier of dissipation. General principles of how to apply these geometric tools to identify optimal protocols are discussed. Focusing on the relevant slow-driving limit, we show how these results can be used to analyze cases in which the experimental control over the system is partial. KW - stochastic thermodynamics KW - thermodynamic control KW - thermodynamic length KW - overdamped brownian systems Y1 - 2022 U6 - https://doi.org/10.1088/2399-6528/ac72f8 SN - 2399-6528 VL - 6 IS - 6 PB - IOP Publ. Ltd. CY - Bristol ER -