bluuebunny/crossref_metadata_2025_split huggingface dataset:
New Infrared Spectral Indices of Luminous Cold Stars: From Early K to M Types
Authors: Messineo Maria , Figer Donald F. , Kudritzki Rolf-Peter , Zhu Qingfeng , Menten Karl M. , Ivanov Valentin D. , Chen C.-H. Rosie 
Published: October 2021

Abstract
We present infrared spectral indices (1.0–2.3 μm) of Galactic late-type giants and red supergiants (RSGs). We used existing and new spectra obtained at resolution power R = 2000 with SpeX on the IRTF telescope. While a large CO equivalent width (EW), at 2.29 μm ([CO, 2.29] ≳ 45 Å) is a typical signature of RSGs later than spectral type M0,

[
CO
]

of K-type RSGs and giants are similar. In the [CO, 2.29] versus [Mg i, 1.71] diagram, RSGs of all spectral types can be distinguished from red giants because the Mg i line weakens with increasing temperature and decreasing gravity. We find several lines that vary with luminosity, but not temperature: Si i (1.59 μm), Sr (1.033 μm), Fe+Cr+Si+CN (1.16 μm), Fe+Ti (1.185 μm), Fe+Ti (1.196 μm), Ti+Ca (1.28 μm), and Mn (1.29 μm). Good markers of CN enhancement are the Fe+Si+CN line at 1.087 μm and CN line at 1.093 μm. Using these lines, at the resolution of SpeX, it is possible to separate RSGs and giants. Contaminant O-rich Mira and S-type AGBs are recognized by strong molecular features due to water vapor features, TiO band heads, and/or ZrO absorption. Among the 42 candidate RSGs that we observed, all but one were found to be late types. Twenty-one have EWs consistent with those of RSGs, 16 with those of O-rich Mira AGBs, and one with an S-type AGB. These infrared results open new, unexplored, potential for searches at low resolution of RSGs in the highly obscured innermost regions of the Milky Way.
SOLES I: The Spin–Orbit Alignment of K2-140 b
Authors: Rice Malena , Wang Songhu , Howard Andrew W. , Isaacson Howard , Dai Fei , Wang Xian-Yu , Beard Corey , Behmard Aida , Brinkman Casey , Rubenzahl Ryan A. , Laughlin Gregory 
Published: October 2021

Abstract
Obliquity measurements for stars hosting relatively long-period giant planets with weak star-planet tidal interactions may play a key role in distinguishing between formation theories for shorter-period hot Jupiters. Few such obliquity measurements have been made to date due to the relatively small sample of known wide-orbiting, transiting Jovian-mass planets and the challenging nature of these targets, which tend to have long transit durations and orbit faint stars. We report a measurement of the Rossiter–McLaughlin effect across the transit of K2-140 b, a Jupiter-mass planet with period P = 6.57 days orbiting a V = 12.6 star. We find that K2-140 is an aligned system with projected spin–orbit angle λ = 0.5° ± 9.7°, suggesting a dynamically cool formation history. This observation builds toward a population of tidally detached giant planet spin–orbit angles that will enable a direct comparison with the distribution of close-orbiting hot-Jupiter orbital configurations, elucidating the prevalent formation mechanisms of each group.
Flare-induced Sunquake Signatures in the Ultraviolet as Observed by the Atmospheric Imaging Assembly
Authors: Quinn Sean , Mathioudakis Mihalis , Nelson Christopher J. , Milligan Ryan O. , Reid Aaron , Jess David B. 
Published: October 2021

Abstract
Sunquakes (SQs) have been routinely observed in the solar photosphere, but it is only recently that signatures of these events have been detected in the chromosphere. We investigate whether signatures of SQs are common in ultraviolet (UV) continua that sample the solar plasma several hundred km above where SQs are typically detected. We analyze observations from the Solar Dynamics Observatory’s Atmospheric Imaging Assembly (SDO/AIA) 1600 and 1700 Å passbands, for SQ signatures induced by the flares of Solar Cycle 24. We base our analysis on the 62 SQs detected in the recent statistical study presented by Sharykin & Kosovichev. We find that 9 out of 62 SQ candidates produced a response that is clearly detected in running-difference images from the AIA 1600 and 1700 Å channels. A binary frequency filter with a width of 2 mHz, centered on 6 mHz, was applied to the data. The first signature of each SQ was detected at distances between 5.2 and 25.7 Mm from the associated flare ribbon. Time–distance and regression analysis allowed us to calculate the apparent transverse velocities of the SQs in the UV data sets and found maximum velocities as high as 41 km s−1, 87 Mm away from the SQ source. Our analysis shows that flare-induced SQ signatures can be detected in the SDO/AIA 1600 and 1700 Å passbands, hinting at their presence in the lower chromosphere. There was no apparent correlation between GOES flare classification and the appearance of the SQ at these heights.
Two Sequences in the Age–Metallicity Relation as Seen from [C/N] Abundances in APOGEE
Authors: Jofré Paula 
Published: October 2021

Abstract
The age–metallicity relation (AMR) is fundamental to study the formation and evolution of the disk. Observations have shown that this relation has a large scatter, which cannot be explained by observational errors only. That scatter is hence attributed to the effects of radial migration in which stars tracing different chemical evolution histories in the disk get mixed. However, the recent study of Nissen et al., using high-precision observational data of solar-type stars, found two relatively tight AMRs. One sequence of older and metal-richer stars probably traces the chemical enrichment history of the inner disk while the other sequence of younger and metal-poorer stars traces the chemical enrichment history of the outer disk. If uncertainties in age measurements increase, these sequences mix, explaining the scatter of the one relation observed in other studies. This work follows up on these results by analyzing an independent sample of red clump giants observed by APOGEE. Because ages for red giants are significantly more uncertain, the [C/N] ratios are considered as a proxy for age. This larger data set is used to investigate these relations at different Galactic radii, finding that these distinct sequences exist only in the solar neighborhood. The APOGEE data set is further used to explore different abundance and kinematical planes to shed light on the nature of these populations.
Chandra X-Ray Observations of V830 Tau: A T Tauri Star Hosting an Evanescent Planet
Authors: Skinner Stephen L. , Güdel Manuel 
Published: October 2021

Abstract
The radial velocity study by Donati et al. (2016) reported the detection of a close-in giant planet in a 4.93 day orbit around the ∼2 Myr old weak-lined T Tauri star V830 Tau. Because of the stringent timescale constraints that a very young host star like V830 Tau would place on hot-Jupiter formation models and inward-migration mechanisms, independent confirmation of the planet’s existence is needed but so far has not been obtained. We present new Chandra X-ray observations of V830 Tau. The Chandra observations in combination with previous XMM-Newton observations reveal strong, variable X-ray emission with an X-ray luminosity spanning the range log L

x
= 30.10–30.87 erg s−1. Chandra High Energy Transmission Grating spectra show emission lines formed over a range of plasma temperatures from ∼4 MK (Ne ix) to ∼16 MK (S xv). At the separation of the reported planet (0.057 au) the X-ray flux is ∼106–107 times greater than the Sun’s X-ray flux at Jupiter. We provide estimates of the X-ray ionization and atmospheric heating rates at the planet’s separation and identify areas of uncertainty that will need to be addressed in any future atmospheric models.
A Bright Ultraviolet Excess in the Transitional 02es-like Type Ia Supernova 2019yvq
Authors: Burke J. , Howell D. A. , Sarbadhicary S. K. , Sand D. J. , Amaro R. C. , Hiramatsu D. , McCully C. , Pellegrino C. , Andrews J. E. , Brown P. J. , Itagaki 板垣 Koichi 公 一 , Shahbandeh M. , Bostroem K. A. , Chomiuk L. , Hsiao E. Y. , Smith Nathan , Valenti S. 
Published: October 2021

Abstract
We present photometric and spectroscopic observations of the nearby Type Ia SN 2019yvq, from its discovery ∼1 day after explosion to ∼100 days after its peak brightness. This SN exhibits several unusual features, most notably an extremely bright UV excess seen within ∼5 days of its explosion. As seen in Swift UV data, this early excess outshines its “peak” brightness, making this object more extreme than other supernovae (SNe) with early UV/blue excesses (e.g., iPTF14atg and SN 2017cbv). In addition, it was underluminous M

B
= −18.4, relatively quickly declining (Δm
15(B) = 1.37), and shows red colors past its early blue bump. Unusual (although not unprecedented) spectral features include extremely broad-lined and high-velocity Si absorption. Despite obvious differences in peak spectra, we classify SN 2019yvq as a transitional member of the 02es-like subclass due to its similarities in several respects (e.g., color, peak luminosity, peak Ti, and nebular [Ca ii]). We model this data set with a variety of published models, including SN ejecta–companion shock interaction and sub-Chandrasekhar-mass white dwarf (WD) double-detonation models. Radio constraints from the VLA place an upper limit of (4.5–20) × 10−8
M
⊙ yr−1 on the mass-loss rate from a symbiotic progenitor, which does not exclude a red giant or main-sequence companion. Ultimately, we find that no one model can accurately replicate all aspects of the data set, and further we find that the ubiquity of early excesses in 02es-like SNe Ia requires a progenitor system that is capable of producing isotropic UV flux, ruling out some models for this class of objects.
The Picture of BLR in 2.5D FRADO: Dynamics and Geometry
Authors: Naddaf Mohammad-Hassan , Czerny Bożena , Szczerba Ryszard 
Published: October 2021

Abstract
The dynamics of the broad line region (BLR) in active galaxies is an open question; direct observational constraints suggest a predominantly Keplerian motion, with possible traces of inflow or outflow. In this paper we study in detail the physically motivated BLR model of Czerny & Hryniewicz based on the radiation pressure acting on dust at the surface layers of the accretion disk (AD). We consider here a nonhydrodynamical approach to the dynamics of the dusty cloud under the influence of radiation coming from the entire AD. We use here a realistic description of the dust opacity, and we introduce two simple geometrical models of the local shielding of the dusty cloud. We show that the radiation pressure acting on dusty clouds is strong enough to lead to dynamical outflow from the AD surface, so the BLR has a dynamical character of a (mostly failed) outflow. The dynamics strongly depends on the Eddington ratio of the source. Large Eddington ratio sources show a complex velocity field and large vertical velocities with respect to the AD surface, while for lower Eddington ratio sources vertical velocities are small and most of the emission originates close to the AD surface. Cloud dynamics thus determines the 3D geometry of the BLR.
A Spectroscopic Analysis of the California-Kepler Survey Sample. II. Correlations of Stellar Metallicities with Planetary Architectures
Authors: Ghezzi Luan , Martinez Cintia F. , Wilson Robert F. , Cunha Katia , Smith Verne V. , Majewski Steven R. 
Published: October 2021

Abstract
We present independent and self-consistent metallicities for a sample of 807 planet-hosting stars from the California-Kepler Survey from an LTE spectroscopic analysis using a selected sample of Fe i and Fe ii lines. Correlations between host-star metallicities, planet radii, and planetary architecture (orbital periods—warm or hot—and multiplicity—single or multiple) were investigated using nonparametric statistical tests. In addition to confirming previous results from the literature, e.g., that overall host-star metallicity distributions differ between hot and warm planetary systems of all types, we report on a new finding: when comparing the median metallicities of hot versus warm systems, the difference for multiple super-Earths is considerably larger when compared to that difference in single super-Earths. The metallicity cumulative distribution functions of hot single super-Earths versus warm single super-Earths indicate different parent stellar populations, while for sub-Neptunes this is not the case. The transition radius between sub-Neptunes and sub-Saturns was examined by comparing the APOGEE metallicity distribution for the Milky Way thin disk in the solar neighborhood with metallicity distributions of host stars segregated based upon the largest known planet in their system. These comparisons reveal increasingly different metallicity distributions as the radius of the largest planet in the systems increases, with the parent stellar metallicities becoming significantly different for R

p
> 2.7 R
⊕. The behavior of the p-values as a function of planet radius undergoes a large slope change at R

p
= 4.4 ± 0.5 R
⊕, indicating the radius boundary between small and large planets.
Toward Optimal Signal Extraction for Imaging X-Ray Polarimetry
Authors: Peirson A. L. , Romani Roger W. 
Published: October 2021

Abstract
We describe an optimal signal extraction process for imaging X-ray polarimetry using an ensemble of deep neural networks. The initial photoelectron angle, used to recover the polarization, has errors following a von Mises distribution. This is complicated by events converting outside of the fiducial gas volume, whose tracks have little polarization sensitivity. We train a deep ensemble of convolutional neural networks to select against these events and to measure event angles and errors for the desired gas-conversion tracks. We show how the expected modulation amplitude from each event gives an optimal weighting to maximize signal-to-noise ratio of the recovered polarization. Applying this weighted maximum likelihood event analysis yields sensitivity (MDP99) improvements of ∼10% over earlier heuristic weighting schemes and mitigates the need to adjust said weighting for the source spectrum. We apply our new technique to a selection of astrophysical spectra, including complex extreme examples, and compare the polarization recovery to the current state of the art.
Characteristics of the Heliospheric Current Sheets at the Sector Boundaries: Wind Observations from 1995–2020
Authors: Liou Kan , Wu Chin-Chun 
Published: October 2021

Abstract
We report results of a statistical study of 1197 heliospheric current sheet (HCS) events associated with the sector boundaries observed by the Wind spacecraft between 1995 and 2020. The average property of the HCS events can be characterized as follows: (1) The width of the current sheets ranges between ∼600 km and 1.1 × 106 km, with an average width of 1.06 ± 2.37 × 105 km; (2) The longitude (in Geocentric Solar-Ecliptic coordinate) of the HCS normal shows a large peak at ∼210° (0° sunward pointing) and a longer tail at smaller angles; (3) The latitudinal angle (inclination) of the HCS normal shows a near symmetric distribution (peak and average ∼0°); (4) The yearly occurrence rate is relatively constant (∼46 or 3.4 events per solar rotation), without showing a clear solar cycle dependence; (5) There are solar cycle variations in the properties of the plasma and field within the current sheets and these variations follow closely with the background solar wind plasma and field; (6) A mild (∼10%) proton temperature increase within the HCS, suggesting that heating of the solar wind proton can occur within the current sheet; and (7) A sudden decrease in the proton temperature anisotropy (T
∥/T
⊥) toward unity within ∼3 hr of the HCS was identified. These results suggest that on the large scale the HCS at 1 au is a relatively stable and persistent solar wind structure throughout the solar cycle. On the small scale the HCS property is probably controlled by the dynamics of the current system, which is still poorly known.
On the Spin Dynamics of Elongated Minor Bodies with Applications to a Possible Solar System Analogue Composition for ‘Oumuamua
Authors: Seligman Darryl Z. , Levine W. Garrett , Cabot Samuel H. C. , Laughlin Gregory , Meech Karen 
Published: October 2021

Abstract
The first interstellar object, 1I/2017 U1 (‘Oumuamua), exhibited several unique properties, including an extreme aspect ratio, a lack of typical cometary volatiles, and a deviation from a Keplerian trajectory. Several authors have hypothesized that the non-gravitational acceleration was caused by either cometary outgassing or radiation pressure. Here, we investigate the spin dynamics of ‘Oumuamua under the action of high-surface-area fractional activity and radiation pressure. We demonstrate that a series of transient jets that migrate across the illuminated surface will not produce a secular increase in the spin rate. We produce 3D tumbling simulations that approximate the dynamics of a surface-covering jet and show that the resulting synthetic light curve and periodogram are reasonably consistent with the observations. Moreover, we demonstrate that radiation pressure also produces a steady spin state. While carbon monoxide (CO) has been dismissed as a possible accelerant because of its non-detection in emission by Spitzer, we show that outgassing from a surface characterized by a modest covering fraction of CO ice can satisfy the non-ballistic dynamics for a plausible range of assumed bulk densities and surface albedos. Spitzer upper limits on CO emission are, however, inconsistent with the CO production necessary to provide the acceleration. Nonetheless, an ad hoc but physically plausible explanation is that the activity level varied greatly during the time that the trajectory was monitored. We reproduce the astrometric analysis presented in Micheli et al., and verify that the non-gravitational acceleration was consistent with stochastic changes in outgassing.
Breaking the Degeneracy in Magnetic Cataclysmic Variable X-Ray Spectral Modeling Using X-Ray Light Curves
Authors: Belloni Diogo , Rodrigues Claudia V. , Schreiber Matthias R. , Castro Manuel , Costa Joaquim E. R. , Hayashi Takayuki , Lima Isabel J. , Luna Gerardo J. M. , Martins Murilo , Oliveira Alexandre S. , Parsons Steven G. , Silva Karleyne M. G. , Stecchini Paulo E. , Stuchi Teresa J. , Zorotovic Monica 
Published: October 2021

Abstract
We present an analysis of mock X-ray spectra and light curves of magnetic cataclysmic variables using an upgraded version of the 3D cyclops code. This 3D representation of the accretion flow allows us to properly model total and partial occultation of the postshock region by the white dwarf as well as the modulation of the X-ray light curves due to the phase-dependent extinction of the preshock region. We carried out detailed postshock region modeling in a four-dimensional parameter space by varying the white dwarf mass and magnetic field strength as well as the magnetosphere radius and the specific accretion rate. To calculate the postshock region temperature and density profiles, we assumed equipartition between ions and electrons; took into account the white dwarf gravitational potential, the finite size of the magnetosphere, and a dipole-like magnetic field geometry; and considered cooling by both bremsstrahlung and cyclotron radiative processes. By investigating the impact of the parameters on the resulting X-ray continuum spectra, we show that there is an inevitable degeneracy in the four-dimensional parameter space investigated here, which compromises X-ray continuum spectral fitting strategies and can lead to incorrect parameter estimates. However, the inclusion of X-ray light curves in different energy ranges can break this degeneracy, and it therefore remains, in principle, possible to use X-ray data to derive fundamental parameters of magnetic cataclysmic variables, which represents an essential step toward understanding their formation and evolution.
Multiwavelength View of the M87 Black Hole Captured by the Event Horizon Telescope
Authors: Principe G. , Lucchini M. ,   on behalf of Event Horizon Telescope (EHT) Multi-Wavelength Science Working Group, EHT Collaboration,   Fermi-LAT Collaboration, H.E.S.S. Collaboration, MAGIC Collaboration, VERITAS Collaboration, EAVN Collaboration
Published: October 2021

Abstract
In 2017, the first image of the center of the M87 galaxy was captured by the Event Horizon Telescope (EHT). It revealed a ring morphology and a size consistent with theoretical expectations for the light pattern around a weakly accreting supermassive black hole of ∼6.5 billion solar masses. In parallel to the EHT measurements, an extensive multi-wavelength (MWL) campaign with ground- and space-based facilities from radio all the way up to the TeV energy range was organized. In this note we will give an overview of the results from this campaign. M87 was found to be in a historically low state. At X-ray energies the emission from the core dominates over HST-1. We present the most complete simultaneous, MWL spectrum of the active nucleus to date.
Articuler connaissances en psychologie cognitive et ingénierie pédagogique
Authors: Tricot André 
Published: October 2021

Quand elle s’intéresse à l’apprentissage, la psychologie cognitive a pour objectif de comprendre comment les humains apprennent. L’ingénierie pédagogique a pour objectif de fournir des connaissances et des méthodes utiles lors de la conception de situations d’enseignement. Les deux disciplines n’ont donc ni le même objet (apprentissage vs . enseignement), ni le même statut (science vs . ingénierie). L’objectif de cet article est de montrer comment on peut articuler connaissances en psychologie cognitive et ingénierie pédagogique. La théorie de la charge cognitive est utilisée comme exemple pour montrer comment on peut produire des connaissances pour l’ingénierie pédagogique à partir d’hypothèses fondées sur une description précise des structures et des fonctions cognitives impliquées dans les apprentissages. Cette théorie illustre que les connaissances pour l’ingénierie sont conditionnelles : leur mise en œuvre dépend de la situation à concevoir et notamment des connaissances antérieures des élèves.
Pourquoi et comment soutenir le développement des compétences émotionnelles chez les élèves âgés de 4 à 7 ans et chez leur enseignant.e ? Apports des sciences cognitives
Authors: Richard Sylvie , Gay Philippe , Gentaz Édouard 
Published: October 2021

Apprendre à identifier, exprimer, comprendre, utiliser et réguler ses émotions et celles d’autrui fait partie intégrante des apprentissages fondateurs d’une scolarité réussie. De nombreuses études en sciences cognitives ont montré que ces compétences jouent un rôle crucial dans la réussite des élèves à l’école et favorisent leurs relations interpersonnelles. Dans un premier temps, nous allons examiner dans quelle mesure le développement de ces compétences émotionnelles est tout particulièrement central chez les élèves qui débutent leur scolarité. Dans un second temps, nous allons proposer deux grands axes d’intervention en classe afin de soutenir leur développement. Nous allons présenter notamment les pratiques d’enseignement « indirectes » (à savoir, être en tant qu’enseignant.e « émotionnellement compétent ») qui visent à les favoriser et nous allons voir qu’il est également possible de mettre ces compétences émotionnelles au défi directement à travers la « labellisation » des émotions, des conversations portant sur les émotions et par le biais des jeux de faire semblant.