bluuebunny/crossref_metadata_2025_split huggingface dataset:
Identification and Parameter Determination of F-type Herbig Stars from LAMOST DR8
Authors: Zhang Yun-Jin , Luo A-Li , Jiang Biwei , Hou Wen , Zuo Fang , Du Bing , Li Shuo , Zhao Yong-Heng 
Published: September 2022

Abstract
We identify 20 F-type Herbig stars and provide a list of 22 pre-main-sequence candidates from LAMOST DR8. The effective temperature, distance, extinction, stellar luminosity, mass, age, and radius are derived for each Herbig star based on optical spectra, photometry, Gaia EDR3 parallaxes, and pre-main-sequence evolutionary tracks. According to spectral energy distribution, 19 F-type Herbig stars belong to Class II YSOs, and one belongs to the flat-spectrum class. Four have Spitzer IRS spectra, of which three show extremely weak polycyclic aromatic hydrocarbon emissions, and three with both amorphous and crystalline silicate emissions share similar parameters and are at the same evolutionary stage. We detect a solar-nearby outbursting EXor Herbig star J034344.48+314309.3, a possible precursor of a Herbig Ae star. Intense emission lines of H i, He i, O i, Na i, and Ca ii originating from the rapid accretion during the outbursts are detected in its optical spectra, and silicate emission features are detected in its infrared spectrum. We also conduct a statistical analysis of the disk properties of all known Herbig stars using the defined infrared spectral indices (

α

J
−

K

S

and

α

K

S

−
W
3

). The proportion of Herbig stars with moderate infrared excesses decreases as effective temperature increases. The majority of the precursors (F, G, or K type) have moderate infrared excesses. Hotter Herbig stars tend to have a larger proportion with large infrared excesses. The trends may be due to the fact that hotter stars have larger areas of re-emitting dust, although there is some scatter due to the particularities of each disk.
The Physical Properties of Low-redshift FeLoBAL Quasars. III. The Location and Geometry of the Outflows
Authors: Choi 최 Hyunseop 현섭 , Leighly Karen M. , Dabbieri Collin , Terndrup Donald M. , Gallagher Sarah C. , Richards Gordon T. 
Published: September 2022

Abstract
We present continued analysis of a sample of low-redshift iron low-ionization broad-absorption-line quasars (FeLoBALQs). Choi et al. presented SimBAL spectral analysis of broad-absorption-line (BAL) outflows in 50 objects. Leighly et al. analyzed the optical emission lines of 30 of those 50 objects and found that they are characterized by either a high accretion rate (L
Bol/L
Edd > 0.3) or low accretion rate (0.03 < L
Bol/L
Edd < 0.3). We report that the outflow velocity is inversely correlated with the BAL location among the high-accretion-rate objects, with the highest velocities observed in parsec-scale outflows. In contrast, the low-Eddington-ratio objects showed the opposite trend. We confirmed the known relationship between the outflow velocity and L
Bol/L
Edd and found that the scatter plausibly originates in the force multiplier (launch radius) in the low(high)-accretion-rate objects. A log volume filling factor between −6 and −4 was found in most outflows but was as high as −1 for low-velocity compact outflows. We investigated the relationship between the observed [O iii] emission and that predicted from the BAL gas. We found that these could be reconciled if the emission-line covering fraction depends on the Seyfert type and BAL location. The difference between the predicted and observed [O iii] luminosity is correlated with the outflow velocity, suggesting that [O iii] emission in high-Eddington-ratio objects may be broad and hidden under Fe ii emission. We suggest that the physical differences in the outflow properties as a function of location in the quasar and accretion rate point to different formation, acceleration, and confinement mechanisms for the two FeLoBALQ types.
A Multiepoch X-Ray Study of the Nearby Seyfert 2 Galaxy NGC 7479: Linking Column Density Variability to the Torus Geometry
Authors: Pizzetti A. , Torres-Albà N. , Marchesi S. , Ajello M. , Silver R. , Zhao X. 
Published: September 2022

Abstract
Active galactic nuclei are powered by accreting supermassive black holes, surrounded by a torus of obscuring material. Recent studies have shown how the torus structure, formerly thought to be homogeneous, appears to be “patchy”: the detection of variability in the line-of-sight hydrogen column density, in fact, matches the description of an obscurer with a complex structure made of clouds with different column density. In this work, we perform a multiepoch analysis of the X-ray spectra of the Seyfert 2 galaxy NGC 7479 in order to estimate its torus properties, such as the average column density and the covering factor. The measurement of the line-of-sight hydrogen column density variability of the torus allows us to obtain an upper limit on the cloud distance from the central engine. In addition, using the X-ray luminosity of the source, we estimate the Eddington ratio to be in a range of λ
Edd = 0.04–0.05 over all epochs.
An Extensive Study of Blazar Broad Emission Line: Changing-look Blazars and the Baldwin Effect
Authors: Xiao Hubing , Fan Junhui , Ouyang Zhihao , Hu Liangjun , Chen Guohai , Fu Liping , Zhang Shaohua 
Published: September 2022

Abstract
It is known that the blazar jet emissions are dominated by nonthermal radiation, while the accretion disk jets are normally dominated by thermal emission. In this work, our aim is to study the connection between the two types of emission by investigating the correlation between the blazar emission-line intensity property, which embodies the nature of an accretion disk, and the γ-ray flux property, which is the representative of jet emission. We compiled a sample of 656 blazars with available emission-line equivalent widths (EWs), the GeV γ-ray flux, and the spectral energy distribution (SED) information from the literature. In this work, we found 55 previous blazar candidates of uncertain types (BCUs) that are now identified as flat-spectrum radio quasars (FSRQs), and found 52 “changing-look” blazars based on their EWs, 45 of which are newly confirmed. These changing-look blazars have a larger accretion ratio (

M

̇

/

M

̇

Edd

) than BL Lacertae (BL Lac) objects. In addition, we suggest that the lower synchrotron peak blazars (LSPs) could be the source of changing-look blazars because 90.7% of the changing-look blazars in this work are confirmed as LSPs. An anticorrelation between EW and continuum intensity, the so-called global “Baldwin effect” (BEff), has been confirmed. We suggest that the steeper global BEff observed for the blazar than for radio-quiet active galactic nuclei (RQ-AGNs) is caused by the inverse Compton scattering of broad-emission-line photons. This interpretation is further supported by the positive correlation between the emission-line EW and intrinsic inverse Compton luminosity.
The Lyα Emission in a C1.4 Solar Flare Observed by the Extreme Ultraviolet Imager aboard Solar Orbiter
Authors: Li Y. , Li Qiao , Song De-Chao , Battaglia Andrea Francesco , Xiao Hualin , Krucker Säm , Schühle Udo , Li Hui , Gan Weiqun , Ding M. D. 
Published: September 2022

Abstract
The hydrogen Lyα (H i Lyα) emission during solar flares has rarely been studied in spatially resolved images, and its physical origin has not been fully understood. In this paper, we present novel Lyα images for a C1.4 solar flare (SOL2021-08-20T22:00) from the Extreme Ultraviolet Imager aboard Solar Orbiter, together with multi-wave-band and multiperspective observations from the Solar Terrestrial Relations Observatory Ahead and the Solar Dynamics Observatory spacecraft. It is found that the Lyα emission has a good temporal correlation with the thermal emissions at 1–8 Å and 5–7 keV, indicating that the flaring Lyα is mainly produced by a thermal process in this small event. However, nonthermal electrons play a minor role in generating Lyα at flare ribbons during the rise phase of the flare, as revealed by the hard X-ray imaging and spectral fitting. Besides originating from flare ribbons, the Lyα emission can come from flare loops, likely caused by plasma heating and also cooling that happen in different flare phases. It is also found that the Lyα emission shows fairly similar features to the He ii
λ304 emission in light curve and spatiotemporal variation, along with small differences. These observational results improve our understanding of the Lyα emission in solar flares and also provide some insights for investigating the Lyα emission in stellar flares.
CLASS: Coronal Line Activity Spectroscopic Survey
Authors: Reefe Michael , Satyapal Shobita , Sexton Remington O. , Doan Sara M. , Secrest Nathan J. , Cann Jenna M. 
Published: September 2022

Abstract
We conduct the first systematic survey of a comprehensive set of the twenty optical coronal lines in the spectra of nearly 1 million galaxies observed by the Sloan Digital Sky Survey (SDSS) Data Release 8 catalog. This includes often overlooked high ionization potential lines such as [Ar x] λ5533, [S xii] λ7609, [Fe xi] λ7892, and [Fe xiv] λ5303. We find that, given the limited sensitivity of SDSS, strong coronal line emission is extremely rare, with only ∼0.03% of the sample showing at least one coronal line, significantly lower than the fraction of galaxies showing optical narrow line ratios (∼17%) or mid-infrared colors (∼2%) indicative of nuclear activity. The coronal line luminosities exhibit a large dynamic range, with values ranging from ∼1034 to 1042 erg s−1. We find that a vast majority (∼80%) of coronal line emitters in dwarf galaxies (M
* < 9.6 × 109
M
⊙) do not display optical narrow line ratios indicative of nuclear activity, in contrast to higher mass galaxies (∼17%). Moreover, we find that the highest ionization potential lines are preferentially found in lower mass galaxies. These findings are consistent with the theory that lower mass black holes found in lower mass galaxies produce a hotter accretion disk, which in turn enhances the higher ionization coronal line spectrum. Future coronal line searches with 30 m class telescopes or JWST may provide a pathway into uncovering the intermediate mass black hole population.
Atmospheric Thermal Emission Effect on Chandrasekhar’s Finite Atmosphere Problem
Authors: Sengupta Soumya 
Published: September 2022

Abstract
The solutions of the diffuse reflection finite atmosphere problem are very useful in the astrophysical context. Chandrasekhar was the first to solve this problem analytically, by considering atmospheric scattering. These results have wide applications in the modeling of planetary atmospheres. However, they cannot be used to model an atmosphere with emission. We solved this problem by including the thermal emission effect along with scattering. Here, our aim is to provide a complete picture of the generalized finite atmosphere problem in the presence of scattering and thermal emission, and to give a physical account of the same. For that, we take an analytical approach using the invariance principle method to solve the diffuse reflection finite atmosphere problem in the presence of atmospheric thermal emission. We established general integral equations of the modified scattering function S(τ; μ, ϕ; μ
0, ϕ
0), transmission function T(τ; μ, ϕ; μ
0, ϕ
0), and their derivatives with respect to τ for a thermally emitting atmosphere. We customize these equations for the case of isotropic scattering and introduce two new functions V(μ), and W(μ), analogous to Chandrasekhar’s X(μ), and Y(μ) functions, respectively. We also derive a transformation relation between the modified S and T functions and give a physical account of the V(μ) and W(μ) functions. Our final results are consistent with those of Chandrasekhar’s at the low emission limit (i.e., only scattering). From the consistency of our results, we conclude that the consideration of the thermal emission effect in the diffuse reflection finite atmosphere problem gives more general and accurate results than considering only scattering.
ALMA/ACA CO Survey of the IC 1459 and NGC 4636 Groups: Environmental Effects on the Molecular Gas of Group Galaxies
Authors: Lee Bumhyun , Wang Jing , Chung Aeree , Ho Luis C. , Wang Ran , Michiyama Tomonari , Molina Juan , Kim Yongjung , Shao Li , Kilborn Virginia , Wang Shun , Lin Xuchen , Kim Dawoon E. , Catinella Barbara , Cortese Luca , Deg Nathan , Denes Helga , Elagali Ahmed , For Bi-Qing , Kleiner Dane , Koribalski Bärbel S. , Lee-Waddell Karen , Rhee Jonghwan , Spekkens Kristine , Westmeier Tobias , Wong O. Ivy , Bigiel Frank , Bosma Albert , Holwerda Benne W. , van der Hulst Jan M. , Roychowdhury Sambit , Verdes-Montenegro Lourdes , Zwaan Martin A. 
Published: September 2022

Abstract
We present new results of a 12CO(J = 1–0) imaging survey using the Atacama Compact Array (ACA) for 31 H i detected galaxies in the IC 1459 and NGC 4636 groups. This is the first CO imaging survey for loose galaxy groups. We obtained well-resolved CO data (∼0.7–1.5 kpc) for a total of 16 galaxies in two environments. By comparing our ACA CO data with the H i and UV data, we probe the impacts of the group environment on the cold gas components (CO and H i gas) and star formation activity. We find that CO and/or H i morphologies are disturbed in our group members, some of which show highly asymmetric CO distributions (e.g., IC 5264, NGC 7421, and NGC 7418). In comparison with isolated galaxies in the xCOLD GASS sample, our group galaxies tend to have low star formation rates and low H2 gas fractions. Our findings suggest that the group environment can change the distribution of cold gas components, including the molecular gas and star formation properties of galaxies. This is supporting evidence that preprocessing in the group-like environment can play an important role in galaxy evolution.
HD 166620: Portrait of a Star Entering a Grand Magnetic Minimum
Authors: Luhn Jacob K. , Wright Jason T. , Henry Gregory W. , Saar Steven H. , Baum Anna C. 
Published: September 2022

Abstract
HD 166620 was recently identified as a Maunder minimum candidate based on nearly 50 years of Ca ii H and K activity data from Mount Wilson and Keck HIRES. These data showed clear cyclic behavior on a 17 yr timescale during the Mount Wilson survey that became flat when picked up later with Keck HIRES planet-search observations. Unfortunately, the transition between these two data sets—and therefore the transition into the candidate Maunder minimum phase—contained little to no data. Here, we present additional Mount Wilson data not present in Baum et al., along with photometry over a nearly 30 yr baseline that definitively traces the transition from cyclic activity to a prolonged phase of flat activity. We present this as conclusive evidence of the star entering a grand magnetic minimum and therefore the first true Maunder minimum analog. We further show that neither the overall brightness nor the chromospheric activity level (as measured by S
HK) is significantly lower during the grand magnetic minimum than its activity cycle minimum, implying that an anomalously low mean or instantaneous activity levels are not a good diagnostic or criterion for identifying additional Maunder minimum candidates. Intraseasonal variability in S
HK, however, is lower in the star’s grand minimum; this may prove a useful symptom of the phenomenon.
A Mathematical Treatment of the Offset Microlensing Degeneracy
Authors: Zhang 张 Keming 可名 , Gaudi B. Scott 
Published: September 2022

Abstract
The offset microlensing degeneracy, recently proposed by Zhang et al., has been shown to generalize the close–wide and inner–outer caustic degeneracies into a unified regime of magnification degeneracy in the interpretation of two-body planetary microlensing observations. While the inner–outer degeneracy expects the source trajectory to pass equidistant to the planetary caustics of the degenerate lens configurations, the offset degeneracy states that the same mathematical expression applies to any combination of the close, wide, and resonant caustic topologies, where the projected star–planet separations differ by an offset (s
A ≠ s
B) that depends on where the source trajectory crosses the lens axis. An important implication is that the s
A = 1/s
B solution of the close–wide degeneracy never strictly manifests in observations except when the source crosses a singular point near the primary. Nevertheless, the offset degeneracy was proposed upon numerical calculations, and no theoretical justification was given. Here, we provide a theoretical treatment of the offset degeneracy, which demonstrates its nature as a mathematical degeneracy. From first principles, we show that the offset degeneracy formalism is exact to zeroth order in the mass ratio (q) for two cases: when the source crosses the lens axis inside of caustics, and for

(

s

A

−

s

B

)

6

≪
1

when crossing outside of caustics. The extent to which the offset degeneracy persists in oblique source trajectories is explored numerically. Finally, it is shown that the superposition principle allows for a straightforward generalization to N-body microlenses with N − 1 planetary lens components (q ≪ 1), which results in a 2
N−1-fold degeneracy.
Connections between the Transient Polar Warming and Solstitial Pause on Mars
Authors: Toigo Anthony D. , Waugh Darryn W. 
Published: September 2022

Abstract
Observations show two different transient atmospheric events around the northern winter solstice on Mars: a warming of the polar lower atmosphere (100–10 Pa) and a reduction in the near-surface wave activity. Here we examine the cause of, and connections between, these two events, and how their occurrence may have changed in past climates using a suite of Mars general circulation model simulations. These simulations show that the polar warming and pause in wave activity are connected, and they occur when there are sufficiently large dust heating rates in the southern (summer) high latitudes, which drive an expansion of the downwelling branch of the Hadley cell into the northern polar region. This causes a poleward shift and weakening of the jet, a warming of the polar lower atmosphere, and reduced baroclinic instability and waves near the surface. The occurrence and strength of the polar warming and wave activity pause increase with obliquity and dust optical depth, with a stronger dependence on obliquity. In past climates with low obliquity the warming and pause are unlikely to occur, or will be very weak, whereas during times of high obliquity they will likely be strong and occur every winter, unless the atmosphere is nearly free of dust.
Applications for zoosporic parasites in aquatic systems (ParAqua)
Authors: Rasconi Serena , Grossart Hans-Peter , Gsell Alena , Ibelings Bastiaan Willem , van de Waal Dedmer , Agha Ramsy , Bacu Ariola , Balode Maija , Beklioğlu Meryem , Berden Zrimec Maja , Botez Florina , Butler Tom , Cerbin Slawomir , Cortina Angela , Cunliffe Michael , Frenken Thijs , Garcés Esther , Gjyli Laura , Golan Yonatan , Guerra Tiago , Iacovides Ayis , Idà Antonio , Kagami Maiko , Kisand Veljo , Leshoski Jovica , Marco Pini , Mazalica Natasa , Miki Takeshi , Moza Maria Iasmina , Neuhauser Sigrid , Özkundakci Deniz , Panksep Kristel , Patcheva Suzana , Pestoric Branka , Petrova Stoyneva Maya , Pinto Diogo , Polle Juergen , Postolache Carmen , Pozo Dengra Joaquín , Reñé Albert , Rychtecky Pavel , Schmeller Dirk S. , Scholz Bettina , Selmeczy Géza , Sime-Ngando Télesphore , Tapolczai Kálmán , Tasevska Orhideja , Trbojevic Ivana , Uzunov Blagoy , Van den Wyngaert Silke , van Donk Ellen , Vanthoor Marieke , Veljanoska Sarafiloska Elizabeta , Wood Susie , Znachor Petr 
Published: September 2022

Zoosporic parasites (i.e. fungi and fungi-like aquatic microorganisms) constitute important drivers of natural populations, causing severe host mortality. Economic impacts of parasitic diseases are notable in the microalgae biotech industry, affecting production of food ingredients, biofuels, pharma- and nutraceuticals.
While scientific research on this topic is gaining traction by increasing studies elucidating the functional role of zoosporic parasites in natural ecosystems, we are currently lacking integrated and interdisciplinary efforts for effectively detecting and controlling parasites in the microalgae industry. To fill this gap we propose to establish an innovative, dynamic European network connecting scientists, industries and stakeholders to optimize information exchange, equalize access to resources and to develop a joint research agenda. ParAqua aims at compiling and making available all information on the occurrence of zoosporic parasites and their relationship with hosts, elucidate drivers and evaluate impacts of parasitism in natural and man-made aquatic environments. We aim to implement new tools for monitoring and prevention of infections, and to create protocols and a Decision Support Tool for detecting and controlling parasites in the microalgae biotech production. Applied knowledge on zoosporic parasites can feed back from industry to ecology, and we therefore will explore whether the developed tools can be applied for monitoring lakes and reservoirs. Short-Term Scientific Missions and Training Schools will be organised specifically for early stage scientists and managers – with a specific focus on ITC – with the aim to share and integrate both scientific and applied expertise and increase exchange between basic and applied researchers and stakeholders.
Filet de sécurité financière international et accords régionaux : quel équilibre ?
Authors: Bussière Matthieu , Cabrillac Bruno , Naef Alain 
Published: September 2022

Le filet de sécurité financière international ( global financial safety net , GFSN) a évolué au cours de la dernière décennie. Si le FMI y tient une place centrale, confortée par l’allocation générale de DTS d’août 2020, les ressources des arrangements financiers régionaux, à la suite de la mise en place du Mécanisme européen de stabilité dans la zone euro, ont renforcé la dimension régionale. L’autre fait saillant de l’évolution du GFSN est la croissance rapide des réserves de change, signe d’une réticence persistante à solliciter le FMI et d’une préférence pour l’auto-assurance. Cet article présente une analyse rétrospective des crises financières au cours des trente dernières années. Il ressort de cette analyse que ces crises ont une forte composante régionale et/ou globale, ce qui plaide pour un filet de sécurité financière plus développé au niveau mondial que régional. Classification JEL : E6, E42, E50, F3, G01, G21
Changement climatique et politique monétaire en pratique
Authors: Odonnat Ivan 
Published: September 2022

Les États signataires de l’Accord de Paris en 2015 se sont engagés à agir pour limiter le réchauffement climatique. Cette lutte contre le changement climatique concerne aussi les banques centrales. Elles vont concevoir des outils pour soutenir les actifs finançant les activités à faible émission de carbone et inversement valoriser négativement les actifs finançant des projets à forte émission de carbone. Acheter des actifs « verts », accorder un traitement de faveur aux actifs verts éligibles en garantie ou mettre en place des facilités de long terme dédiées : la liste des possibilités est longue. Mais ne doit-on pas craindre alors un risque de « politisation » des banques centrales et de « glissement de mission » au-delà de leurs mandats de lutte contre l’inflation ou de soutien à l’activité ? L’article démontre que les banques centrales disposent de trois leviers : l’amélioration des capacités de modélisation macroéconomique pour mieux comprendre les implications du changement climatique pour la politique monétaire ; les exigences de transparence, qui sont à la fois un objectif de l’Union européenne et un levier puissant pour le secteur privé. Rendre les politiques comparables entre tous les pays, c’est la raison d’être du NGFS ( Network for Greening the Financial System ). Classification JEL : E6, E42, E50, F3, G01, G21