bluuebunny/crossref_metadata_2025_split huggingface dataset:
Searching for Black Hole Candidates by LAMOST and ASAS-SN
Authors: Zheng Ling-Lin , Gu Wei-Min , Yi Tuan , Fu Jin-Bo , Mu Hui-Jun , Yang Fan , Wang Song , Bai Zhong-Rui , Sou Hao , Bai Yu , Dong Yi-Ze , Zhang Hao-Tong , Lei Ya-Juan , Wang Junfeng , Wu Jianfeng , Liu Jifeng 
Published: October 2019

Abstract
Most dynamically confirmed stellar-mass black holes (BHs) and their candidates were originally selected from X-ray outbursts. In the present work, we search for BH candidates in the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) survey using the spectra along with photometry from the All Sky Automated Survey for SuperNovae (ASAS-SN), where the orbital period of the binary may be revealed by the periodic light curve, such as the ellipsoidal modulation type. Our sample consists of nine binaries, where each source contains a giant star with large radial velocity variation (

) and periods known from light curves. We focus on the nine sources with long periods (T
ph > 5 days) and evaluate the mass M
2 of the optically invisible companion. Since the observed ΔV
R from only a few repeating spectroscopic observations is a lower limit of the real amplitude, the real mass M
2 can be significantly higher than the current evaluation. It is likely an efficient method to place constraints on M
2 by combining ΔV
R from LAMOST and T
ph from ASAS-SN, particularly by the ongoing LAMOST Medium Resolution Survey.
Entropy Rain: Dilution and Compression of Thermals in Stratified Domains
Authors: Anders Evan H. , Lecoanet Daniel , Brown Benjamin P. 
Published: October 2019

Abstract
Large-scale convective flows called giant cells were once thought to transport the Sun’s luminosity in the solar convection zone, but recent observations have called their existence into question. In place of large-scale flows, some authors have suggested the solar luminosity may instead be transported by small droplets of rapidly falling, low-entropy fluid. This “entropy rain” could propagate as dense vortex rings, analogous to rising buoyant thermals in the Earth’s atmosphere. In this work, we develop an analytical theory describing the evolution of dense, negatively buoyant thermals. We verify the theory with 2D cylindrical and 3D Cartesian simulations of laminar, axisymmetric thermals in highly stratified atmospheres. Our results show that dense thermals fall in two categories: a stalling regime in which the droplets slow down and expand, and a falling regime in which the droplets accelerate and shrink as they propagate downwards. We estimate that solar downflows are in the falling regime and maintain their entropy perturbation against diffusion until they reach the base of the convection zone. This suggests that entropy rain may be an effective nonlocal mechanism for transporting the solar luminosity.
A Survey of Magnetic Field Strengths in the Envelopes of Molecular Clouds via the 18 cm OH Zeeman Effect
Authors: Thompson K. L. , Troland T. H. , Heiles C. 
Published: October 2019

Abstract
We present the results of an extensive Arecibo observational survey of magnetic field strengths in the inter-core regions of molecular clouds to determine their role in the evolution and collapse of molecular clouds as a whole. Sensitive 18 cm OH Zeeman observations of absorption lines from Galactic molecular gas in the direction of extragalactic continuum sources yielded 38 independent measurements of magnetic field strengths. Zeeman detections were achieved at the 3σ level toward nine clouds, while the others revealed sensitive upper limits to the magnetic field strength. Our results suggest that total field strengths in the inter-core regions of giant molecular clouds (GMCs) are about 15 μG.
Preflare Processes, Flux Rope Activation, Large-scale Eruption, and Associated X-class Flare from the Active Region NOAA 11875
Authors: Mitra Prabir K. , Joshi Bhuwan 
Published: October 2019

Abstract
We present a multiwavelength analysis of the eruption of a hot coronal channel associated with an X1.0 flare (SOL2013-10-28T02:03) from the active region NOAA 11875 by combining observations from Atmospheric Imaging Assembly/Solar Dynamics Observatory (SDO), Helioseismic and Magnetic Imager/SDO, Reuven Ramaty High Energy Solar Spectroscopic Imager, and Hiraiso Radio Spectrograph. EUV images at high coronal temperatures indicated the presence of a hot channel at the core of the active region from the early preflare phase evidencing the preexistence of a quasi-stable magnetic flux rope. The hot channel underwent an activation phase after a localized and prolonged preflare event occurring adjacent to one of its footpoints. Subsequently, the flux rope continued to rise slowly for ≈16 minutes during which soft X-ray flux gradually built-up characterizing a distinct precursor phase. The flux rope transitioned from the state of slow rise to the eruptive motion with the onset of the impulsive phase of the X1.0 flare. The eruptive expansion of the hot channel is accompanied by a series of type III radio bursts in association with the impulsive rise of strong hard X-ray nonthermal emissions that included explicit hard X-ray sources of energies up to ≈50 keV from the coronal loops and ≈100 keV from their footpoint locations. Our study contains evidence that preflare activity occurring within the spatial extent of a stable flux rope can destabilize it toward eruption. Moreover, sudden transition of the flux rope from the state of slow rise to fast acceleration precisely bifurcated the precursor and the impulsive phases of the flare, which points toward a feedback relationship between early coronal mass ejection dynamics and the strength of the large-scale magnetic reconnection.
Radio Spectroscopic Imaging of a Solar Flare Termination Shock: Split-band Feature as Evidence for Shock Compression
Authors: Chen 陈 Bin 彬 , Shen 沈呈 Chengcai 彩 , Reeves Katharine K. , Guo 郭 Fan 帆 , Yu 余思 Sijie 捷 
Published: October 2019

Abstract
Solar flare termination shocks have been suggested as one of the promising drivers for particle acceleration in solar flares, yet observational evidence remains rare. By utilizing radio dynamic spectroscopic imaging of decimetric stochastic spike bursts in an eruptive flare, Chen et al. found that the bursts form a dynamic surface-like feature located at the ending points of fast plasma downflows above the looptop, interpreted as a flare termination shock. One piece of observational evidence that strongly supports the termination shock interpretation is the occasional split of the emission band into two finer lanes in frequency, similar to the split-band feature seen in fast-coronal-shock-driven type II radio bursts. Here, we perform spatially, spectrally, and temporally resolved analysis of the split-band feature of the flare termination shock event. We find that the ensemble of the radio centroids from the two split-band lanes each outlines a nearly co-spatial surface. The high-frequency lane is located slightly below its low-frequency counterpart by ∼0.8 Mm, which strongly supports the shock-upstream–downstream interpretation. Under this scenario, the density compression ratio across the shock front can be inferred from the frequency split, which implies a shock with a Mach number of up to 2.0. Further, the spatiotemporal evolution of the density compression along the shock front agrees favorably with results from magnetohydrodynamics simulations. We conclude that the detailed variations of the shock compression ratio may be due to the impact of dynamic plasma structures in the reconnection outflows, which results in distortion of the shock front.
On Kinetic Instabilities Driven By Ion Temperature Anisotropy and Differential Flow in the Solar Wind
Authors: Sun Heyu , Zhao Jinsong , Xie Huasheng , Wu Dejin 
Published: October 2019

Abstract
The ion temperature anisotropy instability is widely thought of as a constraint on the distribution of the ion perpendicular and parallel temperatures in the solar wind. Besides the ion temperature anisotropy, proton and alpha particle beams are permeating in the solar wind. Therefore, this paper presents a comprehensive investigation on unstable waves resulting from both ion temperature anisotropy and ion beams. It finds that the strongest electromagnetic cyclotron instability triggers the left-hand circularly polarized Alfvén/proton-cyclotron wave propagating along the background magnetic field. The strongest fast-magnetosonic/whistler firehose instability generates the right-hand circularly polarized fast-magnetosonic/whistler wave propagating reversely to the background magnetic field. The mirror instability preferably drives oblique mirror mode waves with two anticorrelated perpendicular magnetic components. The Alfvén firehose instability is prior to generating oblique Alfvén waves with two unbalanced perpendicular magnetic components that are nearly positive-correlated. Due to the effects of streaming proton and alpha particles, both the mirror and Alfvén firehose instabilities produce slowly propagating unstable waves in comparison to nonpropagating waves in motionless plasmas. The differential proton and alpha particle flows result in the ion/ion beam instability, destabilizing obliquely propagating Alfvén/proton-cyclotron waves. The ion/ion beam instability can provide a constraint on electromagnetic fluctuations in the low-beta region. Moreover, this paper clearly explores the dependence of the frequency and electromagnetic polarization on the normal angle for each kind of instability, which could be useful for distinguishing the instability mechanism in the solar wind.
The Effect of the Approach to Gas Disk Gravitational Instability on the Rapid Formation of Gas Giant Planets
Authors: Boss Alan P. 
Published: October 2019

Abstract
Observational evidence suggests that gas disk instability may be responsible for the formation of at least some gas giant exoplanets, particularly massive or distant gas giants. With regard to close-in gas giants, Boss used the β cooling approximation to calculate hydrodynamical models of inner gas disk instability, finding that provided disks with low values of the initial minimum Toomre stability parameter (i.e., Q

i
< 2 inside 20 au) form, fragmentation into self-gravitating clumps could occur even for β as high as 100 (i.e., extremely slow cooling). Those results implied that the evolution of disks toward low Q

i
must be taken into account. This paper presents such models: initial disk masses of 0.091 M
⊙ extending from 4 to 20 au around a 1 M
⊙ protostar, with a range (1–100) of β cooling parameters, the same as in Boss, but with all the disks starting with Q

i
= 2.7, i.e., gravitationally stable, and allowed to cool from their initial outer disk temperature of 180 K to as low as 40 K. All the disks eventually fragment into at least one dense clump. The clumps were again replaced by virtual protoplanets (VPs) and the masses and orbits of the resulting ensemble of VPs compare favorably with those of Boss, supporting the claim that disk instability can form gas giants rapidly inside 20 au, provided that sufficiently massive protoplanetary disks exist.
Do Current and Magnetic Helicities Have the Same Sign?
Authors: Russell A. J. B. , Demoulin P. , Hornig G. , Pontin D. I. , Candelaresi S. 
Published: October 2019

Abstract
Current helicity, H

c
, and magnetic helicity, H

m
, are two main quantities used to characterize magnetic fields. For example, such quantities have been widely used to characterize solar active regions and their ejecta (magnetic clouds). It is commonly assumed that H

c
and H

m
have the same sign, but this has not been rigorously addressed beyond the simple case of linear force-free fields. We aim to answer whether H

m

H

c
≥ 0 in general, and whether it is true over some useful set of magnetic fields. This question is addressed analytically and with numerical examples. The main focus is on cylindrically symmetric straight flux tubes, referred to as flux ropes (FRs), using the relative magnetic helicity with respect to a straight (untwisted) reference field. Counterexamples with H

m

H

c
< 0 have been found for cylindrically symmetric FRs with finite plasma pressure, and for force-free cylindrically symmetric FRs in which the poloidal field component changes direction. Our main result is a proof that H

m

H

c
≥ 0 is true for force-free cylindrically symmetric FRs where the toroidal field and poloidal field components are each of a single sign, and the poloidal component does not exceed the toroidal component. We conclude that the conjecture that current and magnetic helicities have the same sign is not true in general, but it is true for a set of FRs of importance to coronal and heliospheric physics.
Supermassive Black Hole Binary Candidates from the Pan-STARRS1 Medium Deep Survey
Authors: Liu T. , Gezari S. , Ayers M. , Burgett W. , Chambers K. , Hodapp K. , Huber M. E. , Kudritzki R.-P. , Metcalfe N. , Tonry J. , Wainscoat R. , Waters C. 
Published: October 2019

Abstract
We present a systematic search for periodically varying quasar and supermassive black hole binary (SMBHB) candidates in the Pan-STARRS1 Medium Deep Survey (MDS). From ∼9000 color-selected quasars in an ∼50 °2 sky area, we initially identify 26 candidates with more than 1.5 cycles of variation. We extend the baseline of observations via our imaging campaign with the Discovery Channel Telescope and the Las Cumbres Observatory network and reevaluate the candidates using a more rigorous, maximum likelihood method. Using a range of statistical criteria and assuming the damped random walk model for normal quasar variability, we identify one statistically significant periodic candidate. We also investigate the capabilities of detecting SMBHBs with the Large Synoptic Survey Telescope using our study with MDS as a benchmark and explore any complementary multiwavelength evidence for SMBHBs in our sample.
AGN-Driven Outflows in Dwarf Galaxies
Authors: Manzano-King Christina M. , Canalizo Gabriela , Sales Laura V. 
Published: October 2019

Abstract
We present spatially resolved kinematic measurements of active galactic nucleus (AGN)-driven outflows in dwarf galaxies in the stellar mass range ∼6 × 108–9 × 109
M
⊙, selected from SDSS DR7 and DR8 and followed-up with Keck/LRIS spectroscopy. We find spatially extended (∼1 half-light radius), high-velocity ionized gas outflows (W
80 up to ∼2000 km s−1) in 13/50 dwarf galaxies with and without an AGN. Outflow velocities in all 13 galaxies exceed the escape velocities of their halos. Nine of these 13 galaxies are classified as AGNs according to their narrow line flux ratios. Of these, six have outflow components with emission-line ratios consistent with AGN ionization. Although black holes (BHs) have been known to populate the centers of at least a few dwarf galaxies and indirect evidence of AGN quenching of star formation in dwarfs has begun to surface, our measurements constitute the first direct detection and measurement of AGN impact on the large-scale kinematics and gas content in dwarf galaxies. Furthermore, we find evidence suggestive of ongoing star formation suppression, possibly regulated by the AGN. Galaxy formation models must therefore be able to account not only for the formation and growth of BHs at the centers of dwarf galaxies, but should also be revised to include AGNs as important—and perhaps dominant—sources of feedback in low-mass galaxies.
A Family Picture: Tracing the Dynamical Path of the Structural Properties of Multiple Populations in Globular Clusters
Authors: Dalessandro Emanuele , Cadelano M. , Vesperini E. , Martocchia S. , Ferraro F. R. , Lanzoni B. , Bastian N. , Hong J. , Sanna N. 
Published: October 2019

Abstract
We studied the spatial distributions of multiple stellar populations (MPs) in a sample of 20 globular clusters (GCs) spanning a broad range of dynamical ages. The differences between first-population (FP) and second-population (SP) stars were measured by means of the parameter A
+, defined as the area enclosed between their cumulative radial distributions. We provide the first purely observational evidence of the dynamical path followed by MPs from initial conditions toward a complete FP–SP spatial mixing. Less dynamically evolved clusters have SP stars more centrally concentrated than FPs, while in more dynamically evolved systems the spatial differences between FP and SP stars decrease and eventually disappear. By means of an appropriate comparison with a set of numerical simulations, we show that these observational results are consistent with the evolutionary sequence expected by the long-term dynamical evolution of clusters forming with an initially more centrally concentrated SP subsystem. This result is further supported by the evidence of a trend between A
+ and the stage of GC dynamical evolution inferred by the ratio between the present-day and the initial mass of the cluster.
Les associations culturelles : état des lieux et typologie
Authors: Rathle Jean-Philippe 
Published: October 2019

En 2013, on compte 1,3 million d’associations en France, dont une sur cinq déclare une activité culturelle, soit 263 400 associations. Près de 100 000 associations culturelles (37 % de l’ensemble) œuvrent dans le domaine du spectacle vivant, 65 000 dans les arts visuels et l’écriture (lieux d’exposition, ateliers et collectifs d’artistes), 50 000 dans l’animation socioculturelle, 35 000 dans le patrimoine et 15 000 dans l’enseignement artistique et culturel. 16 % des associations culturelles ont recours à l’emploi salarié et l’ensemble des associations culturelles mobilisent 3,5 millions de bénévoles. On estime à 200 000 le nombre de salariés dans les associations culturelles, soit 77 000 en équivalent temps plein, car les trois quarts d’entre eux sont employés à temps partiel, et 60 % sous contrat à durée indéterminée. L’ensemble des associations culturelles disposent de ressources courantes de 7,1 milliards d’euros, dont 84 % sont concentrées dans les associations employeuses. Parmi les 43 300 associations culturelles employeuses, les disparités d’organisation et de fonctionnement sont importantes. L’étude dégage quatre profils d’associations, aux caractéristiques très différentes : les associations dédiées au spectacle vivant (46 %), celles dédiées à l’animation et à l’éducation artistique et culturelle (33 %), aux arts visuels et à l’écriture (11 %) et au patrimoine (9 %).
Trois élèves sur quatre touchés par au moins une action ou un projet relevant de l’éducation artistique et culturelle
Authors: Ayoub Anissa , Berthomier Nathalie , Octobre Sylvie , Thoumelin Claire , Touahir Mustapha 
Published: October 2019

Au cours de l’année 2017-2018, trois élèves sur quatre ont été touchés par au moins une action ou un projet relevant de l’éducation artistique et culturelle ( eac ) : 82 % dans le premier degré et 62 % dans les collèges. Les disparités de l’offre en matière d’action ou de projet sont en partie liées aux caractéristiques des établissements scolaires, notamment à l’ancienneté moyenne des enseignants. En éducation prioritaire, la part d’élèves touchés par les actions ou projets est moindre, respectivement 78 % en école et 55 % en collège. Les différences entre établissements sont également liées à l’organisation de l’éducation artistique et culturelle et à la présence d’un coordinateur de l’éducation artistique et culturelle (dont sont dotées plus de deux écoles sur cinq) ou d’un référent eac (présents dans deux tiers des collèges). Outre les actions et projets d’éducation artistique et culturelle, près de 100 % des écoles et des collèges organisent au moins une activité en lien avec l’éducation artistique et culturelle (sortie culturelle, rencontre avec un artiste, etc.). Dans trois écoles sur quatre et dans plus de neuf collèges sur dix, au moins une activité est réalisée en partenariat avec une structure culturelle. Enfin, au cours de l’année 2017-2018, la chorale est présente dans 56 % des écoles et 84 % des collèges.
Une « démocratie radicale » pas si radicale ?
Authors: Cervera-Marzal Manuel 
Published: October 2019

Résumé Introduite tardivement au sein de l’univers intellectuel francophone, la pensée de Chantal Mouffe fait l’objet d’un intérêt croissant. La philosophe est présentée tour à tour comme une des principales théoriciennes de la gauche radicale, comme une disciple de Carl Schmitt et comme une opposante résolue à la tradition libérale. Pourtant, de l’aveu même de la principale intéressée, Chantal Mouffe se place davantage dans le camp de la « socialdémocratie » que dans celui de la « gauche radicale », elle marque une différence fondamentale à l’égard de Carl Schmitt, et elle revendique son attachement à l’idéal libéral. Partant de ces décalages, le présent article défend l’idée que la pensée de Chantal Mouffe est perçue comme plus radicale qu’elle ne l’est réellement. Chantal Mouffe entend réformer la tradition libérale plutôt que l’infirmer.
A Campanha Nacional de Educação dos Cegos: uma leitura a partir da imprensa jornalística dos anos 1960 e 1970
Authors: Cardoso Fernanda Luí­sa de Miranda , Martínez Silvia Alicia 
Published: October 2019

Busca-se, neste artigo, compreender as linhas de ação e o funcionamento da Campanha Nacional para Educação dos Cegos, durante as décadas de 1960 e 1970. Essa campanha integrava um ‘modelo campanhista de política social’, subordinada ao Ministério da Educação e Cultura, e atuava em linhas de ação que envolviam a difusão do livro didático; o ensino de braile no Curso Normal; a qualificação de cegos para atividades industriais; a assistência financeira; e o convênio com a Campanha Nacional de Educação Rural. A imprensa jornalística é priorizada como fonte pelas peculiaridades não proporcionadas por outras fontes ‘como a riqueza de debates, anseios e utopias dos projetos educativos’.
História do ensino superior em Mato Grosso: das iniciativas frustradas à criação de um sistema universitário
Authors: Benfica Tiago Alinor Hoissa 
Published: October 2019

A fim de se visualizar a instalação das primeiras instituições de ensino superior no antigo Estado de Mato Grosso, foi necessário um olhar sobre as mudanças do campo educacional ocorridas no contexto nacional. A discussão, embasada em pesquisa bibliográfica de trabalhos memorialistas e acadêmicos, busca se concentrar nas experiências da construção de instituições de ensino superior no Estado de Mato Grosso, na década de 1960, e alcança o período da divisão do Estado, ocorrida no ano de 1977. Desse modo, expõe-se uma grade de informações que permite se entender o processo de criação da Universidade Federal de Mato Grosso e da Universidade Federal de Mato Grosso do Sul. Nesse ponto, defende-se que a porção sul do antigo Mato Grosso foi mais dinâmica do que a parte norte na promoção das primeiras escolas de ensino superior. A institucionalização de escolas de ensino superior ocorreu em um contexto nacional que favorecia o seu processo de interiorização, escolas essas encabeçadas por lideranças locais, profissionais liberais que se utilizavam do discurso da promoção da modernização regional para adquirirem poder e reconhecimento com as iniciativas empreendidas no campo educacional. Já o papel do sistema universitário era, essencialmente, a qualificação da mão de obra local.
A alternativa para o progresso: o nacionalismo-desenvolvimentista, seus intelectuais e o planejamento educacional nos anos 1960 no Brasil
Authors: Santos Lincoln de Araújo 
Published: October 2019

As origens do desenvolvimentismo como projeto político e suas influências no pensamento social e educacional brasileiro aglutinaram na década de 1960 um grupo de intelectuais comprometidos com esse ideário articulados por instituições e pelo Estado. Num cenário de crise política e social, Celso Furtado, Darcy Ribeiro, Anísio Teixeira e Paulo Freire atuaram como aqueles que pensaram o Brasil com base em uma convergência de ideias que os aproximava do nacionalismo-desenvolvimentista. A análise das fontes documentais identifica nas narrativas os sinais do ideário de um projeto nacional de desenvolvimento, destacando a natureza do Plano Nacional de Educação, de 1962, e o Plano Trienal de Educação, de 1963.