bluuebunny/crossref_metadata_2025_split huggingface dataset:
Arecibo-Green Bank-LOFAR Carbon Radio Recombination Line Observations toward Cold H i Clouds
Authors: Roshi D. Anish , Peters W. M. , Emig K. L. , Salas P. , Oonk J. B. R. , Lebrón M. E. , Dickey J. M. 
Published: January 2022

Abstract
We present results from a search for radio recombination lines in three H i self-absorbing (HISA) clouds at 750 MHz and 321 MHz with the Robert C. Byrd Green Bank Telescope, and in three Galactic plane positions at 327 MHz with the Arecibo Telescope. We detect carbon recombination lines (CRRLs) in the direction of DR4 and DR21, as well as in the Galactic plane position G34.94 + 0.0. We additionally detect hydrogen recombination lines in emission in five of the six sightlines, and a Helium line at 750 MHz toward DR21. Combining our new data with 150 MHz Low Frequency Array detections of CRRL absorption toward DR4 and DR21, we estimate the electron densities of the line-forming regions by modeling the line width as a function of frequency. The estimated densities are in the range 1.4 → 6.5 cm−3 toward DR4, for electron temperatures 200 → 20 K. A dual line-forming region with densities between 3.5 → 24 cm−3 and 0.008 → 0.3 cm−3 could plausibly explain the observed line width as a function of frequency on the DR21 sight line. The central velocities of the CRRLs compare well with CO emission and HISA lines in these directions. The cloud densities estimated from the CO lines are smaller (at least a factor of five) than those of the CRRL-forming regions. It is likely that the CRRL-forming and HISA gas is located in a denser, shocked region either at the boundary of or within the CO emitting cloud.
Metallicity Distribution Function of the Eridanus II Ultra-faint Dwarf Galaxy from Hubble Space Telescope Narrowband Imaging
Authors: Fu Sal Wanying , Weisz Daniel R. , Starkenburg Else , Martin Nicolas , Ji Alexander P. , Patel Ekta , Boylan-Kolchin Michael , Côté Patrick , Dolphin Andrew E. , Longeard Nicolas , Mateo Mario L. , Sandford Nathan R. 
Published: January 2022

Abstract
We use deep narrowband CaHK (F395N) imaging taken with the Hubble Space Telescope (HST) to construct the metallicity distribution function (MDF) of Local Group ultra-faint dwarf galaxy Eridanus II (Eri II). When combined with archival F475W and F814W data, we measure metallicities for 60 resolved red giant branch stars as faint as m
F475W ∼ 24 mag, a factor of ∼4× more stars than current spectroscopic MDF determinations. We find that Eri II has a mean metallicity of [Fe/H] = −2.50

−
0.07

+
0.07

and a dispersion of

σ

[
Fe

/

H
]

=

0.42

−
0.06

+
0.06

, which are consistent with spectroscopic MDFs, though more precisely constrained owing to a larger sample. We identify a handful of extremely metal-poor star candidates (EMP; [Fe/H] < −3) that are marginally bright enough for spectroscopic follow-up. The MDF of Eri II appears well described by a leaky box chemical evolution model. We also compute an updated orbital history for Eri II using Gaia eDR3 proper motions, and find that it is likely on first infall into the Milky Way. Our findings suggest that Eri II underwent an evolutionary history similar to that of an isolated galaxy. Compared to MDFs for select cosmological simulations of similar mass galaxies, we find that Eri II has a lower fraction of stars with [Fe/H] < −3, though such comparisons should currently be treated with caution due to a paucity of simulations, selection effects, and known limitations of CaHK for EMPs. This study demonstrates the power of deep HST CaHK imaging for measuring the MDFs of UFDs.
Observationally Constraining the Starspot Properties of Magnetically Active M67 Sub-subgiant S1063
Authors: Gosnell Natalie M. , Gully-Santiago Michael A. , Leiner Emily M. , Tofflemire Benjamin M. 
Published: January 2022

Abstract
Our understanding of the impact of magnetic activity on stellar evolution continues to unfold. This impact is seen in sub-subgiant stars, defined to be stars that sit below the subgiant branch and red of the main sequence in a cluster color–magnitude diagram. Here we focus on S1063, a prototypical sub-subgiant in open cluster M67. We use a novel technique combining a two-temperature spectral decomposition and light-curve analysis to constrain starspot properties over a multiyear time frame. Using a high-resolution near-infrared IGRINS spectrum and photometric data from K2 and ASAS-SN, we find a projected spot filling factor of 32% ± 7% with a spot temperature of 4000 ± 200 K. This value anchors the variability seen in the light curve, indicating the spot filling factor of S1063 ranged from 20% to 45% over a four-year time period with an average spot filling factor of 30%. These values are generally lower than those determined from photometric model comparisons but still indicate that S1063, and likely other sub-subgiants, are magnetically active spotted stars. We find observational and theoretical comparisons of spotted stars are nuanced due to the projected spot coverage impacting estimates of the surface-averaged effective temperature. The starspot properties found here are similar to those found in RS CVn systems, supporting classifying sub-subgiants as another type of active giant star binary system. This technique opens the possibility of characterizing the surface conditions of many more spotted stars than previous methods, allowing for larger future studies to test theoretical models of magnetically active stars.
Radiation and Polarization Signatures from Magnetic Reconnection in Relativistic Jets. II. Connection with γ-Rays
Authors: Zhang Haocheng , Li Xiaocan , Giannios Dimitrios , Guo Fan , Thiersen Hannes , Böttcher Markus , Lewis Tiffany , Venters Tonia 
Published: January 2022

Abstract
It is commonly believed that blazar jets are relativistic magnetized plasma outflows from supermassive black holes. One key question is how the jets dissipate magnetic energy to accelerate particles and drive powerful multiwavelength flares. Relativistic magnetic reconnection has been proposed as the primary plasma physical process in the blazar emission region. Recent numerical simulations have shown strong acceleration of nonthermal particles that may lead to multiwavelength flares. Nevertheless, previous works have not directly evaluated γ-ray signatures from first-principles simulations. In this paper, we employ combined particle-in-cell and polarized radiation transfer simulations to study multiwavelength radiation and optical polarization signatures under the leptonic scenario from relativistic magnetic reconnection. We find harder-when-brighter trends in optical and Fermi-LAT γ-ray bands as well as closely correlated optical and γ-ray flares. The swings in optical polarization angle are also accompanied by γ-ray flares with trivial time delays. Intriguingly, we find highly variable synchrotron self-Compton signatures due to inhomogeneous particle distributions during plasmoid mergers. This feature may result in fast γ-ray flares or orphan γ-ray flares under the leptonic scenario, complementary to the frequently considered minijet scenario. It may also imply neutrino emission with low secondary synchrotron flux under the hadronic scenario, if plasmoid mergers can accelerate protons to very high energy.
Observing Ram Pressure at Work in Intermediate Redshift Clusters with MUSE: The Case of Abell 2744 and Abell 370
Authors: Moretti Alessia , Radovich Mario , Poggianti Bianca M. , Vulcani Benedetta , Gullieuszik Marco , Werle Ariel , Bellhouse Callum , Bacchini Cecilia , Fritz Jacopo , Soucail Genevieve , Richard Johan , Franchetto Andrea , Tomičić Neven , Omizzolo Alessandro 
Published: January 2022

Abstract
Ram pressure stripping has been proven to be effective in shaping galaxy properties in dense environments at low redshift. The availability of Multi Unit Spectroscopic Explorer (MUSE) observations of a sample of distant (z ∼ 0.3–0.5) clusters has allowed one to search for galaxies subject to this phenomenon at significant lookback times. In this paper we describe how we discovered and characterized 13 ram-pressure-stripped galaxies in the central regions of two intermediate redshift (z ∼ 0.3–0.4) clusters, A2744 and A370, using the MUSE spectrograph. Emission-line properties as well as stellar features have been analyzed to infer the presence of this gas-only stripping mechanism, that produces spectacular ionized gas tails (Hα and even more astonishing [O ii](3727, 3729)) departing from the main galaxy body. The inner regions of these two clusters reveal the predominance of such galaxies among blue star-forming cluster members, suggesting that ram pressure stripping was even more effective at intermediate redshift than in today’s universe. Interestingly, the resolved [O ii]/Hα line ratio in the stripped tails is exceptionally high compared to that in the disks of these galaxies, (which is comparable to that in normal low-z galaxies), suggesting lower gas densities and/or an interaction with the hot surrounding intracluster medium.
Direct Observation of the Radial Magnetic Field Gradient in HD 58260 from Spectropolarimetry of NLTE Lines in Emission
Authors: Giarrusso Marina 
Published: January 2022

Abstract
Because of the unquestionable presence of magnetic fields in stars, their role in the structure of stellar atmospheres has for a long time been a subject of speculation. In our contribution to this discussion we present spectropolarimetric evidence of the decrease of the radial component of the magnetic field with altitude in the atmosphere of HD 58260, a B-type magnetic star on the main sequence. We show that the Stokes V profiles of metal lines in emission of the outer atmosphere are evidence for a field three times weaker than absorption lines from inner layers. The extra flow of energetic particles due to the magnetic-gradient pumping mechanism could be at the origin of the magnetospheres surrounding this class of stars and at the basis of the high-energy phenomena observed. We also list a series of spectral lines useful for measuring the surface field of early-type stars.
Stochastic Electron Acceleration by Temperature Anisotropy Instabilities under Solar Flare Plasma Conditions
Authors: Riquelme Mario , Osorio Alvaro , Verscharen Daniel , Sironi Lorenzo 
Published: January 2022

Abstract
Using 2D particle-in-cell plasma simulations, we study electron acceleration by temperature anisotropy instabilities, assuming conditions typical of above-the-loop-top sources in solar flares. We focus on the long-term effect of T

e,⊥ > T

e,∥ instabilities by driving the anisotropy growth during the entire simulation time through imposing a shearing or a compressing plasma velocity (T

e,⊥ and T

e,∥ are the temperatures perpendicular and parallel to the magnetic field). This magnetic growth makes T

e,⊥/T

e,∥ grow due to electron magnetic moment conservation, and amplifies the ratio ω
ce/ω
pe from ∼0.53 to ∼2 (ω
ce and ω
pe are the electron cyclotron and plasma frequencies, respectively). In the regime ω
ce/ω
pe ≲ 1.2–1.7, the instability is dominated by oblique, quasi-electrostatic modes, and the acceleration is inefficient. When ω
ce/ω
pe has grown to ω
ce/ω
pe ≳ 1.2–1.7, electrons are efficiently accelerated by the inelastic scattering provided by unstable parallel, electromagnetic z modes. After ω
ce/ω
pe reaches ∼2, the electron energy spectra show nonthermal tails that differ between the shearing and compressing cases. In the shearing case, the tail resembles a power law of index α

s
∼ 2.9 plus a high-energy bump reaching ∼300 keV. In the compressing runs, α

s
∼ 3.7 with a spectral break above ∼500 keV. This difference can be explained by the different temperature evolutions in these two types of simulations, suggesting that a critical role is played by the type of anisotropy driving, ω
ce/ω
pe, and the electron temperature in the efficiency of the acceleration.
Let the Great World Spin: Revealing the Stormy, Turbulent Nature of Young Giant Exoplanet Analogs with the Spitzer Space Telescope
Authors: Vos Johanna M. , Faherty Jacqueline K. , Gagné Jonathan , Marley Mark , Metchev Stanimir , Gizis John , Rice Emily L. , Cruz Kelle 
Published: January 2022

Abstract
We present a survey for photometric variability in young, low-mass brown dwarfs with the Spitzer Space Telescope. The 23 objects in our sample show robust signatures of youth and share properties with directly imaged exoplanets. We present three new young objects: 2MASS J03492367+0635078, 2MASS J09512690−8023553, and 2MASS J07180871−6415310. We detect variability in 13 young objects, and find that young brown dwarfs are highly likely to display variability across the L2–T4 spectral type range. In contrast, the field dwarf variability occurrence rate drops for spectral types >L9. We examine the variability amplitudes of young objects and find an enhancement in maximum amplitudes compared to field dwarfs. We speculate that the observed range of amplitudes within a spectral type may be influenced by secondary effects such as viewing inclination and/or rotation period. We combine our new rotation periods with the literature to investigate the effects of mass on angular momentum evolution. While high-mass brown dwarfs (>30M
Jup) spin up over time, the same trend is not apparent for lower-mass objects (<30M
Jup), likely due to the small number of measured periods for old, low-mass objects. The rotation periods of companion brown dwarfs and planetary-mass objects are consistent with those of isolated objects with similar ages and masses, suggesting similar angular momentum histories. Within the AB Doradus group, we find a high-variability occurrence rate and evidence for common angular momentum evolution. The results are encouraging for future variability searches in directly imaged exoplanets with facilities such as the James Webb Space Telescope and 30 m telescopes.
The Milky Way Revealed by Variable Stars. I. Sample Selection of RR Lyrae Stars and Evidence for Merger History
Authors: Ablimit Iminhaji , Zhao Gang , Teklimakan Uy. , Shi Jian-Rong , Abdusalam Kunduz 
Published: January 2022

Abstract
In order to study the Milky Way, RR Lyrae (RRL) variable stars identified by Gaia, ASAS-SN, and ZTF sky survey projects have been analyzed as tracers in this work. Photometric and spectroscopic information of 3417 RRLs including proper motions, radial velocity, and metallcity are obtained from observational data of Gaia, LAMOST, GALAH, APOGEE, and RAVE. Precise distances of RRLs with typical uncertainties less than 3% are derived by using a recent comprehensive period–luminosity–metallicity relation. Our results from kinematical and chemical analysis provide important clues for the assembly history of the Milky Way, especially for the Gaia–Sausage ancient merger. The kinematical and chemical trends found in this work are consistent with those of recent simulations that indicated that the Gaia–Sausage merger had a dual origin in the Galactic thick disk and halo. As recent similar works have found, the halo RRL sample in this work contains a subset of radially biased orbits besides a more isotropic component. This higher orbital anisotropy component amounts to β ≃ 0.8, and it contributes between 42% and 83% of the halo RRLs at 4 < R( kpc) < 20.
A Cross-laboratory Comparison Study of Titan Haze Analogs: Surface Energy
Authors: Li 李 Jialin 嘉霖 , Yu 余 Xinting 馨婷 , Sciamma-O’Brien Ella , He Chao , Sebree Joshua A. , Salama Farid , Hörst Sarah M. , Zhang Xi 
Published: January 2022

Abstract
In Titan’s nitrogen-methane atmosphere, photochemistry leads to the production of complex organic particles, forming Titan’s thick haze layers. Laboratory-produced aerosol analogs, or “tholins,” are produced in a number of laboratories; however, most previous studies have investigated analogs produced by only one laboratory rather than a systematic, comparative analysis. In this study, we performed a comparative study of an important material property, the surface energy, of seven tholin samples produced in three independent laboratories under a broad range of experimental conditions, and we explored their commonalities and differences. All seven tholin samples are found to have high surface energies and are therefore highly cohesive. Thus, if the surface sediments on Titan are similar to tholins, future missions such as Dragonfly will likely encounter sticky sediments. We also identified a commonality between all the tholin samples: a high dispersive (nonpolar) surface energy component of at least 30 mJ m−2. This common property could be shared by the actual haze particles on Titan as well. Given that the most abundant species interacting with the haze on Titan (methane, ethane, and nitrogen) are nonpolar in nature, the dispersive surface energy component of the haze particles could be a determinant factor in condensate−haze and haze−lake liquid interactions on Titan. With this common trait of tholin samples, we confirmed the findings of a previous study by Yu et al. that haze particles are likely good cloud condensation nuclei for methane and ethane clouds and would likely be completely wetted by the hydrocarbon lakes on Titan.
A new genus and species of leptonetid spiders (Araneae, Leptonetidae) from Guangdong Province, China
Authors: Yang Kuiwen , Li Hanchao , Tong Yanfeng , Bian Dongju 
Published: January 2022

The spider family Leptonetidae Simon, 1890 includes 20 genera and 366 species from North America, the Mediterranean Region and Asia. Currently, 132 species belonging to six genera have been recorded in China.A new genus and species of leptonetid spiders,Yueleptoneta dongxinggen. et sp. n., is described from Guangdong Province, China.Yueleptonetagen. n. is distinct from the other genera in the chelicerae having the stridulatory file on the lateral margin and the male palp having a tarsal spur, lacking strong spines or apophyses on the femur and tibia.
Identités télévisuelles
Authors: Lafon Benoît 
Published: January 2022

Confrontés à la multiplication des chaînes de télévision, les acteurs dits historiques (TF1, France Télévisions, Canal + et M6) ont développé des stratégies de marque à l’échelle non plus des chaînes mais des groupes. Cet article analyse ces stratégies en étudiant d’une part le design d’antenne et l’autopromotion de ces groupes (autopromotion croisée des chaînes sur leurs antennes et sur leurs médias délinéarisés MyTF1, France.tv, MyCanal, 6Play) et, d’autre part, en appréhendant les positionnements des directions de la marque des groupes télévisuels (entretiens avec des directeurs de la marque et artistiques desdits groupes, prises de position dans les médias lors d’événements promotionnels). Ce faisant, il apparaît que la programmation reste au cœur du média télévisuel, mais une programmation labellisée par la marque télévisuelle et étendue doublement : à l’échelle des groupes télévisuels, ainsi qu’en direction des médias délinéarisés en ligne édités ceux-ci. La communication de marque est désormais une tâche essentielle pour les groupes de télévision, visant à rendre identifiable le média télévisuel, tout comme à labelliser ses programmes en vue de leur valorisation, en linéaire et en ligne.
Les cérémonies Miss France, de la télévision à Twitter
Authors: Leveneur-Martel Laurence 
Published: January 2022

Les commentaires numériques générés par les émissions de télévision sur Twitter font l’objet de plusieurs études depuis 2006 (Segado et al. , 2015). Miss France est l’un des programmes les plus commentés de la télévision française sur ce réseau social numérique. TF1 et la société de production Banijay développent autour de ce programme une communication très rodée. Grâce aux archives web mises à la disposition des chercheurs par l’Institut National de l’Audiovisuel, nous proposons dans cet article une analyse diachronique et sémio-pragmatique de ce phénomène, en nous appuyant sur un corpus d’émissions diffusées entre 2015 et 2019, ainsi que les tweets qui y sont relatifs. Notre analyse de ces contenus confirme que les pratiques qui se nouent autour de la télévision sociale s’institutionnalisent (Jeanne-Perrier, 2010) et que les différents « cercles » de commentateurs et leurs discours se cristallisent autour de postures récurrentes et rituelles.
Notules sur le lexique arabe vernaculaire/semi-vernaculaire dans les Manāqib Abī l-Qāsim al-Misrātī de l’écrivain Ǧamāl al-dīn Muḥammad b. Ḫalaf al-Misrātī al-Qayrawānī (après 1035/1626)
Authors: Meouak Mohamed 
Published: January 2022

[fr] Ces notules traitent de la question des données lexicales en arabe vernaculaire/semi-vernaculaire collectées dans les Manāqib Abī l-Qāsim al-Misrātī de l’écrivain Ǧamāl al-dīn Muḥammad b. Ḫalaf al-Misrātī al-Qayrawānī (après 1035/1626). On rappelle aux historiens et linguistes l’intérêt qu’il y aurait à étudier le matériel textuel en arabe vernaculaire/semi-vernaculaire de Tunisie-Libye au XIe/XVIIe siècle afin de contribuer à une meilleure connaissance de l’histoire sociale des habitudes linguistiques. Les informations sont exposées en écriture arabe et réparties en deux sections : lexique commun et formules composées/segments de phrases.
Squandermania or Nigerian urban renaissance? Houses, hotels and Nollywood in an African creative economy
Authors: Bud Alexander 
Published: January 2022

Au cours des dernières décennies, le paysage igbo a été transformé par l’essor spectaculaire de gigantesques maisons et d’hôtels. Les spécialistes du développement et les commentateurs locaux ont réagi de manière cinglante, rejetant ce phénomène comme étant du gaspillage et un investissement peu productif. Cet article propose de réévaluer ceci en considérant ces formes de consommation à travers les nouveaux concepts d’« entrepreneuriat culturel » et de « scènes de consommation ». Il retrace la manière dont les entrepreneurs culturels ont relié les espaces des maisons et des hôtels à la production de Nollywood. Cette articulation – tantôt facile et complémentaire, tantôt conflictuelle et instable – a généré de nombreuses nouvelles pratiques. Celles-ci vont d’un nouveau style architectural populaire de la maison Nollywood à la transformation des maisons et des hôtels en infrastructure de localisation des films, en passant par une culture de stars facilitant les activités commerciales dans les bars d’hôtel, jusqu’à l’émergence de types d’espaces entièrement nouveaux mêlant de manière inédite les plateaux de tournage et les résidences. La conclusion introduit le concept de la « Renaissance urbaine nigériane » pour réfléchir aux implications économiques plus larges de cette dynamique créatrice.
Les entrepreneurs camerounais face aux pouvoirs publics. Querelles autour de « l’émergence »
Authors: Amougou Gérard 
Published: January 2022

Le réengagement du gouvernement camerounais envers des politiques de planification du développement n’a pas débouché sur le rapprochement escompté avec les entrepreneurs nationaux. Alors que le développement du secteur privé et le subventionnement de l’entrepreneuriat national sont au centre du programme en vue de l’« émergence » à l’horizon 2035, la mise en œuvre de cette dernière montre surtout la prépondérance d’une élite politique soucieuse de sa propre préservation au détriment de la transformation structurelle de l’économie. Néanmoins, la résilience de certains entrepreneurs nationaux et leur aspiration à jouer un rôle central dans le secteur privé camerounais alimentent une querelle autour de la notion officielle de l’émergence, et qui informe le processus de formation de l’État.