bluuebunny/crossref_metadata_2025 huggingface dataset:
Tidally Excited Modes and δ Scuti Pulsations in the Eclipsing Triple Star IM Persei
Authors: Lee Jae Woo , Hong Kyeongsoo , Kim Hye-Young
Published: February 2021

IM Per is a triple star system whose eclipsing pair masses and radii are accurate to within 1%. The Transiting Exoplanet Survey Satellite (TESS) light curve of the program target exhibits partial eclipses and multiple oscillations with millimagnitude-level amplitudes. It is found that the oscillations affect eclipse timing measurements. Binary modeling of the high-quality TESS data indicates that the eclipsing components of the triple system are twin dwarfs with parameters of M
2/M
1 = 0.995, R
2/R
1 = 0.901, and Δ(

–

) = 12 K in an eccentric (e = 0.049), detached configuration. The third light of l
3 = 0.054 may mostly come from a G-type tertiary companion. Our predicted parallax of 1.52 ± 0.09 mas is concurrent with the Gaia measurement of 1.52 ± 0.05 mas. Multifrequency analysis of the outside-eclipse residuals reveals 22 significant pulsation signals: 4 in the gravity-mode region (0.03−2.22 day−1) and 18 in the pressure-mode region (9.19−25.12 day−1). Of the low frequencies, f
11 and f
14 are orbital harmonics that can be identified as tidally excited modes. The pulsation periods and constants for the high frequencies, and the position in the Cepheid instability strip demonstrate that the pulsating component of IM Per is a δ Sct variable.
Speckle Imaging Characterization of Radial Velocity Exoplanet Systems
Authors: Dalba Paul A. , Kane Stephen R. , Howell Steve B. , Horch Elliott P. , Li Zhexing , Hirsch Lea A. , Burt Jennifer , Brandt Timothy D. , Močnik Teo , Henry Gregory W. , Everett Mark E. , Rosenthal Lee J. , Howard Andrew W.
Published: February 2021

We conducted speckle imaging observations of 53 stellar systems that were members of long-term radial velocity (RV) monitoring campaigns and exhibited substantial accelerations indicative of planetary or stellar companions in wide orbits. Our observations were made with blue and red filters using the Differential Speckle Survey Instrument at Gemini-South and the NN-Explore Exoplanet Stellar Speckle Imager at the WIYN telescope. The speckle imaging identifies eight luminous companions within 2″ of the primary stars. In three of these systems—HD 1388, HD 87359, and HD 104304—the properties of the imaged companion are consistent with the RV measurements, suggesting that these companions may be associated with the primary and the cause of the RV variation. For all 53 stellar systems, we derive differential magnitude limits (i.e., contrast curves) from the imaging. We extend this analysis to include upper limits on companion mass in systems without imaging detections. In 25 systems, we rule out companions with masses greater than 0.2 M
⊙, suggesting that the observed RV signals are caused by late-M dwarfs or substellar (potentially planetary) objects. On the other hand, the joint RV and imaging analysis almost entirely rules out planetary explanations of the RV signal for HD 19522 and suggests that the companion must have an angular separation below a few tenths of an arcsecond. This work highlights the importance of combined RV and imaging observations for characterizing the outer regions of nearby planetary systems.
Target Prioritization and Observing Strategies for the NEID Earth Twin Survey
Authors: Gupta Arvind F. , Wright Jason T. , Robertson Paul , Halverson Samuel , Luhn Jacob , Roy Arpita , Mahadevan Suvrath , Ford Eric B. , Bender Chad F. , Blake Cullen H. , Hearty Fred , Kanodia Shubham , Logsdon Sarah E. , McElwain Michael W. , Monson Andrew , Ninan Joe P. , Schwab Christian , Stefánsson Guðmundur , Terrien Ryan C.
Published: February 2021

NEID is a high-resolution optical spectrograph on the WIYN 3.5 m telescope at Kitt Peak National Observatory and will soon join the new generation of extreme precision radial velocity instruments in operation around the world. We plan to use the instrument to conduct the NEID Earth Twin Survey (NETS) over the course of the next 5 years, collecting hundreds of observations of some of the nearest and brightest stars in an effort to probe the regime of Earth-mass exoplanets. Even if we take advantage of the extreme instrumental precision conferred by NEID, it will be difficult to disentangle the weak (∼10 cm s−1) signals induced by such low-mass, long-period exoplanets from stellar noise for all but the quietest host stars. In this work, we present a set of quantitative selection metrics which we use to identify an initial NETS target list consisting of stars conducive to the detection of exoplanets in the regime of interest. We also outline a set of observing strategies with which we aim to mitigate uncertainty contributions from intrinsic stellar variability and other sources of noise.
Two Luminous Post-AGB Stars in the Galactic Globular Cluster M19
Authors: Bond Howard E. , Davis Brian D. , Siegel Michael H. , Ciardullo Robin
Published: February 2021

We report the discovery of a luminous “yellow” post–asymptotic giant branch (PAGB) star in the globular cluster (GC) M19 (NGC 6273), identified during our uBVI survey of Galactic GCs. The uBVI photometric system is optimized to detect stars with large Balmer discontinuities, indicating very low surface gravities and high luminosities. The spectral energy distribution (SED) of the star is consistent with an effective temperature of about 6250 K and a surface gravity of

. We use Gaia data to show that the star’s proper motion and radial velocity are consistent with cluster membership. One aim of our program is to test yellow PAGB stars as candidate Population II standard candles for determining extragalactic distances. We derive a visual absolute magnitude of M

V
= − 3.39 ± 0.09 for the M19 star. This is in close agreement with the M

V
values found for yellow PAGB stars in the GCs ω Cen, NGC 5986, and M79, indicating a very narrow luminosity function. These objects are 4 mag brighter than RR Lyrae variables, and they can largely avoid the issues of interstellar extinction that are a problem for Population I distance indicators. We also identified a second luminous PAGB object in M19, this one a hotter “UV-bright” star. Its SED is consistent with an effective temperature of about 11,750 K and

. The two objects have nearly identical bolometric luminosities,

and 3.22, respectively.
A Simplified Photodynamical Model for Planetary Mass Determination in Low-eccentricity Multitransiting Systems
Authors: Yoffe Gideon , Ofir Aviv , Aharonson Oded
Published: February 2021

Inferring planetary parameters from transit timing variations (TTVs) is challenging for small exoplanets because their transits may be so weak that determination of individual transit timing is difficult or impossible. We implement a useful combination of tools that together provide a numerically fast global photodynamical model. This is used to fit the TTV-bearing light curve, in order to constrain the masses of transiting exoplanets in low-eccentricity, multiplanet systems—and small planets in particular. We present inferred dynamical masses and orbital eccentricities in four multi-planet systems from Kepler's complete long-cadence data set. We test our model against Kepler-36/KOI-277, a system with some of the most precisely determined planetary masses through TTV inversion methods, and find masses of 5.56+0.41
−0.45 and 9.76+0.79
−0.89

for Kepler-36 b and c, respectively—consistent with literature in both value and error. We then improve the mass determination of the four planets in Kepler-79/KOI-152, where literature values were physically problematic to 12.5+4.5
−3.6, 9.5+2.3
−2.1, 11.3+2.2
−2.2 and 6.3+1.0
−1.0

for Kepler-79 b, c, d, and e, respectively. We provide new mass constraints where none existed before for two systems. These are 12.5+3.2
−2.6

for Kepler-450 c, and 3.3+1.7
−1.0 and 17.4+7.1
−3.8

for Kepler-595 c (previously KOI-547.03) and b, respectively. The photodynamical code used here, called PyDynamicaLC, is made publicly available.
Formation of Dust Filaments in the Diffuse Envelopes of Molecular Clouds
Authors: Beitia-Antero Leire , Gómez de Castro Ana I. , Vallejo Juan C.
Published: February 2021

The path to understanding star formation processes begins with the study of the formation of molecular clouds. The outskirts of these clouds are characterized by low column densities that allow the penetration of ultraviolet radiation, resulting in a nonnegligible ionization fraction and the charging of the small dust grains that are mixed with the gas; this diffuse phase is then coupled to the ambient magnetic field. Despite the general assumption that dust and gas are tightly correlated, several observational and theoretical studies have reported variations in the dust-to-gas ratio toward diffuse and cold clouds. In this work, we present the implementation of a new charged particles module for analyzing the dust dynamics in molecular cloud envelopes. We study the evolution of a single population of small charged grains (0.05 μm) in the turbulent, magnetized molecular cloud envelope using this module. We show that variations in the dust-to-gas ratio arise due to the coupling of the grains with the magnetic field, forming elongated dust structures decoupled from the gas. This emphasizes the importance of considering the dynamics of charged dust when simulating the different phases of the interstellar medium, especially for star formation studies.
On the Decay of Sunspot Groups and Their Internal Parts in Detail
Authors: Muraközy Judit
Published: February 2021

The decay of sunspot groups is a relatively unknown field since most studies have focused mainly on the decay of sunspots or sunspot groups, but only on small samples. As an extension of the recent work of Muraközy (2020), which is based on a large verified sample, this study investigates not only the long-term behavior of the decay of sunspot groups but also the dynamics of their parts. The aim of the present work is to search for dependencies of the decay process in order to find physical conditions that modify or contribute to the decay. The investigations are based on the catalog of the SoHO Debrecen Sunspot Database (SDD) and the Greenwich Photoheliographic Results as well as the Debrecen Photoheliographic Data. Altogether more than 750 sunspot groups were considered. The decay rates have been calculated for the total, umbral, and penumbral area of the groups and in the case of the SDD’s groups they have been calculated for both the leading and the following parts. The decay rates depend linearly on the maximum areas and ranged from 30 to 50 millionths of the solar hemisphere (MSH) day−1 for the sunspot groups and penumbrae and 5–10 MSH day−1 for the umbrae throughout the cycle. The decay rates fall significantly during the Gnevyshev gap and show 4 + 4 Schwabe cyclical variations in the ascending/descending phases, but it is always higher in the northern hemisphere. There is a slight decrease in the decay rates in the activity range toward higher latitudes.
Detecting Reconnection Events in Kinetic Vlasov Hybrid Simulations Using Clustering Techniques
Authors: Sisti Manuela , Finelli Francesco , Pedrazzi Giorgio , Faganello Matteo , Califano Francesco , Ponti Francesca Delli
Published: February 2021

Kinetic turbulence in magnetized space plasmas has been extensively studied via in situ observations, numerical simulations, and theoretical models. In this context, a key point concerns the formation of coherent current structures and their disruption through magnetic reconnection. We present automatic techniques aimed at detecting reconnection events in a large data set of numerical simulations. We make use of clustering techniques known as K-means and DBscan (usually referred to in literature as unsupervised machine-learning approaches), and other methods based on thresholds of standard reconnection proxies. All our techniques also use a threshold on the aspect ratio of the regions selected. We test the performance of our algorithms. We propose an optimal aspect ratio to be used in the automated machine-learning algorithm: AR = 18. The performance of the unsupervised approach results in it being strongly competitive with respect to those of other methods based on thresholds of standard reconnection proxies.
Reconciling X-Ray and λ21 cm H I Absorption Gas Column Densities toward Obscured AGN
Authors: Liszt Harvey
Published: February 2021

Hydrogen column densities inferred from X-ray absorption are typically 5–30 times larger than the neutral atomic hydrogen column densities derived from λ21 cm H I absorption toward radio-loud active galactic nuclei (AGN). Some part of the difference is ascribed to uncertainty in the spin temperature T
sp = 100 K that is often used to convert λ21 cm H I absorption to N(H I). Here we propose another way to infer the gas column from H I absorption. In our Galaxy there is a nearly linear correlation between the inteferometrically measured integrated λ21 cm absorption ϒH I and reddening, ϒH I ∝ E(B–V)1.10 for ϒH I ≳ 0.7 km s−1 or E(B–V) ≳ 0.04 mag. Scaling E(B–V) then provides the total gas column density N(H) from the same dust column that is responsible for optical obscuration and X-ray absorption, without calculating N(H I). Values of N(H) so derived typically exceed N(H I) by a factor 4 because the ubiquitous Galactic λ21 cm H I absorption samples only a portion of the interstellar gas. If the well-studied case of Hydra-A is a guide, even very large disparities in X-ray and λ21 cm gas column densities can be explained by resolving the core radio continuum and inferring N(H) from λ21 cm absorption. Milky Way conditions are often invoked in discussion of obscured AGN, so the empirical relationship seen in the Milky Way should be a relevant benchmark.
Fe vii Emission Lines in the Wavelength Range 193–197 Å
Authors: Young Peter R. , Ryabtsev Alexander N. , Landi Enrico
Published: February 2021

The identifications of Fe vii emission lines in the wavelength range 193–197 Å are discussed in the light of new measurements of laboratory spectra and atomic data calculations. This region is of importance to studies of solar spectra from the EUV Imaging Spectrometer (EIS) on board the Hinode spacecraft, which has its peak sensitivity at these wavelengths. Ten lines are measured, arising from seven fine structure levels in the 3p
53d
3 configuration. Two lines have not previously been reported and lead to new experimental energies for the

levels. Updated experimental energies are obtained for the remaining levels. The new atomic model is used to compute theoretical values for the two density diagnostic ratios λ196.21/λ195.39 and λ196.21/λ196.06, and densities are derived from EIS spectra of coronal loop footpoints.
Optimized Statistical Approach for Comparing Multi-messenger Neutron Star Data
Authors: Raithel Carolyn A. , Özel Feryal , Psaltis Dimitrios
Published: February 2021

The neutron star equation of state is now being constrained from a diverse set of multi-messenger data, including gravitational waves from binary neutron star mergers, X-ray observations of the neutron star radius, and many types of laboratory nuclear experiments. These measurements are often mapped to a common domain for comparison with one another or are used to constrain the predictions of theoretical equations of state. We explore here the statistical biases that can arise when such multi-messenger data are compared or combined across different domains. We find that placing Bayesian priors individually in each domain of measurement can lead to biased constraints. We present a new prescription for defining Bayesian priors consistently across different experiments, which will allow for robust cross-domain comparisons. Using the first two binary neutron star mergers as an example, we show that a uniform prior in the tidal deformability can produce inflated evidence for large radii, while a uniform prior in the radius points toward smaller radii. Finally, using this new prescription, we provide a status update on multi-messenger constraints on the neutron star radius.
Updated BaSTI Stellar Evolution Models and Isochrones. II. α-enhanced Calculations
Authors: Pietrinferni Adriano , Hidalgo Sebastian , Cassisi Santi , Salaris Maurizio , Savino Alessandro , Mucciarelli Alessio , Verma Kuldeep , Aguirre Victor Silva , Aparicio Antonio , Ferguson Jason W.
Published: February 2021

This is the second paper of a series devoted to presenting an updated release of the BaSTI (a Bag of Stellar Tracks and Isochrones) stellar model and isochrone library. Following the publication of the updated solar-scaled library, here we present the library for an α-enhanced heavy element distribution. These new α-enhanced models account for all improvements and updates in the reference solar metal distribution and physics inputs, as in the new solar-scaled library. The models cover a mass range between 0.1 and 15 M
⊙, 18 metallicities between [Fe/H] = −3.20 and +0.06 with [α/Fe] = +0.4, and a He-to-metal enrichment ratio ΔY/ΔZ = 1.31. For each metallicity, He-enhanced stellar models are also provided. The isochrones cover (typically) an age range between 20 Myr and 14.5 Gyr, including consistently the pre-main-sequence phase. The asteroseismic properties of the theoretical models have also been calculated. Models and isochrones have been compared with results from independent calculations, with the previous BaSTI release, and also with selected observations, to test the accuracy/reliability of these new calculations. All stellar evolution tracks, asteroseismic properties, and isochrones are publicly available at http://basti-iac.oa-teramo.inaf.it.
A Comparison of Star-forming Clumps and Tidal Tails in Local Mergers and High-redshift Galaxies
Authors: Elmegreen Debra Meloy , Elmegreen Bruce G. , Whitmore Bradley C. , Chandar Rupali , Calzetti Daniela , Lee Janice C. , White Richard , Cook David , Ubeda Leonardo , Mok Angus , Linden Sean T.
Published: February 2021

The Clusters, Clumps, Dust, and Gas in Extreme Star-forming Galaxies (CCDG) survey with the Hubble Space Telescope includes multiwavelength imaging of 13 galaxies less than 100 Mpc away, spanning a range of morphologies and sizes, from blue compact dwarfs to luminous infrared galaxies, all with star formation rates in excess of hundreds of solar masses per year. Images of seven merging galaxies in the CCDG survey were artificially redshifted to compare with galaxies at z = 0.5, 1, and 2. Most redshifted tails have surface brightnesses that would be visible at z = 0.5 or 1 but not at z = 2 due to cosmological dimming. Giant star clumps are apparent in these galaxies; the 51 measured have similar sizes, masses, and colors to clumps in observed high-z systems in the UDF, GEMS, GOODS, and CANDELS surveys. These results suggest that some clumpy high-z galaxies without observable tidal features could be the result of mergers. The local clumps also have the same star formation rate per unit area and stellar surface density as clumps observed at intermediate and high redshift, so they provide insight into the substructure of distant clumps. A total of 1596 star clusters brighter than M

V
= −9 were identified within the boundaries of the local clumps. The cluster magnitude distribution function is a power law with approximately the same slope (∼−1 for a plot of number versus log luminosity) for all the galaxies both inside and outside the clumps and independently of clump surface brightness.
Carbon Chain Chemistry in Hot-core Regions around Three Massive Young Stellar Objects Associated with 6.7 GHz Methanol Masers
Authors: Taniguchi Kotomi , Herbst Eric , Majumdar Liton , Caselli Paola , Tan Jonathan C. , Li Zhi-Yun , Shimoikura Tomomi , Dobashi Kazuhito , Nakamura Fumitaka , Saito Masao
Published: February 2021

We have carried out observations of CCH (N = 1 − 0), CH3CN (J = 5 − 4), and three 13C isotopologues of HC3N (J = 10 − 9) toward three massive young stellar objects (MYSOs), G12.89+0.49, G16.86−2.16, and G28.28−0.36, with the Nobeyama 45 m radio telescope. Combined with previous results on HC5N, the column density ratios of N(CCH)/N(HC5N), hereafter the CCH/HC5N ratios, in the MYSOs are derived to be ∼15. This value is lower than that in a low-mass warm carbon chain chemistry (WCCC) source by more than one order of magnitude. We compare the observed CCH/HC5N ratios with hot-core model calculations. The observed ratios in the MYSOs can be best reproduced by models when the gas temperature is ∼85 K, which is higher than in L1527, a low-mass WCCC source (∼35 K). These results suggest that carbon-chain molecules detected around the MYSOs exist at least partially in higher temperature regions than those in low-mass WCCC sources. There is no significant difference in column density among the three 13C isotopologues of HC3N in G12.89+0.49 and G16.86-2.16, while HCC13CN is more abundant than the others in G28.28–0.36. We discuss carbon-chain chemistry around the three MYSOs based on the CCH/HC5N ratio and the 13C isotopic fractionation of HC3N.
Maps of Magnetic Field Strength in the OMC-1 Using HAWC+ FIR Polarimetric Data
Authors: Guerra Jordan A. , Chuss David T. , Dowell C. Darren , Houde Martin , Michail Joseph M. , Siah Javad , Wollack Edward J.
Published: February 2021

Far-infrared dust polarimetry enables the study of interstellar magnetic fields via tracing of the polarized emission from dust grains that are partially aligned with the direction of the field. The advent of high-quality polarimetric data has permitted the use of statistical methods to extract both the direction and magnitude of the magnetic field. In this work, the Davis–Chandrasekhar–Fermi technique is used to make maps of the plane-of-sky (POS) component of the magnetic field in the Orion Molecular Cloud (OMC-1) by combining polarization maps at 53, 89, 154 and 214 μm from HAWC+/SOFIA with maps of density and velocity dispersion. In addition, maps of the local dispersion of polarization angles are used in conjunction with Zeeman measurements to estimate a map of the strength of the line-of-sight (LOS) component of the field. Combining these maps, information about the three-dimensional magnetic field configuration (integrated along the LOS) is inferred over the OMC-1 region. POS magnetic field strengths of up to 2 mG are observed near the BN/KL object, while the OMC-1 bar shows strengths of up to a few hundred μG. These estimates of the magnetic field components are used to produce maps of the mass-to-magnetic-flux ratio (M/Φ)—a metric for probing the conditions for star formation in molecular clouds—and determine regions of sub- and supercriticality in OMC-1. Such maps can provide invaluable input and comparison to MHD simulations of star formation processes in filamentary structures of molecular clouds.
Large-scale Variation in Reionization History Caused by Baryon–Dark Matter Streaming Velocity
Authors: Park 박 Hyunbae 현 배 , Shapiro Paul R. , Ahn Kyungjin , Yoshida Naoki , Hirano Shingo
Published: February 2021

At cosmic recombination, there was supersonic relative motion between baryons and dark matter, which originated from baryonic acoustic oscillations in the early universe. This motion has been considered to have a negligible impact on the late stage of cosmic reionization because the relative velocity quickly decreases. However, recent studies have suggested that the recombination in gas clouds smaller than the local Jeans mass (≲108
M
☉) can affect the reionization history by boosting the number of ultraviolet photons required for ionizing the intergalactic medium. Motivated by this, we performed a series of radiation-hydrodynamic simulations to investigate whether the streaming motion can generate variation in the local reionization history by smoothing out clumpy small-scale structures and lowering the ionizing photon budget. We found that the streaming velocity can add a variation of Δz

e
∼ 0.05–0.5 in the end-of-reionization redshift, depending on the level of X-ray preheating and the time evolution of ionizing sources. The variation tends to be larger when the ionizing efficiency of galaxies decreases toward later times. Given the long spatial fluctuation scales of the streaming motion (≳100 Mpc), it can help to explain the Lyα opacity variation observed from quasars and leave large-scale imprints on the ionization field of the intergalactic medium during the reionization. The pre-reionization heating by X-ray sources is another critical factor that can suppress small-scale gas clumping and can diminish the variation in z

e
introduced by the streaming motion.
Wind Mass-loss Rates of Stripped Stars Inferred from Cygnus X-1
Authors: Neijssel Coenraad J. , Vinciguerra Serena , Vigna-Gómez Alejandro , Hirai Ryosuke , Miller-Jones James C. A. , Bahramian Arash , Maccarone Thomas J. , Mandel Ilya
Published: February 2021

Recent observations of the high-mass X-ray binary Cygnus X-1 have shown that both the companion star (41 solar masses) and the black hole (21 solar masses) are more massive than previously estimated. Furthermore, the black hole appears to be nearly maximally spinning. Here, we present a possible formation channel for the Cygnus X-1 system that matches the observed system properties. In this formation channel, we find that the orbital parameters of Cygnus X-1, combined with the observed metallicity of the companion, imply a significant reduction in mass loss through winds relative to commonly used prescriptions for stripped stars.
A Smoking Gun for Planetesimal Formation: Charge-driven Growth into a New Size Range
Authors: Teiser Jens , Kruss Maximilian , Jungmann Felix , Wurm Gerhard
Published: February 2021

Collisions electrically charge grains, which promotes growth by coagulation. We present aggregation experiments with three large ensembles of basalt beads (150–180 μm), two of which are charged, while one remains almost neutral as a control system. In microgravity experiments, free collisions within these samples are induced with moderate collision velocities (0–0.2 m s−1). In the control system, coagulation stops at (sub-)mm size while the charged grains continue to grow. A maximum agglomerate size of 5 cm is reached, limited only by bead depletion in the free volume. For the first time, charge-driven growth well into the centimeter range is directly proven by experiments. In protoplanetary disks, this agglomerate size is well beyond the critical size needed for hydrodynamic particle concentration as, e.g., by the streaming instabilities.
Late-time Observations of Calcium-rich Transient SN 2019ehk Reveal a Pure Radioactive Decay Power Source
Authors: Jacobson-Galán Wynn V. , Margutti Raffaella , Kilpatrick Charles D. , Raymond John , Berger Edo , Blanchard Peter K. , Bobrick Alexey , Foley Ryan J. , Gomez Sebastian , Hosseinzadeh Griffin , Milisavljevic Danny , Perets Hagai , Terreran Giacomo , Zenati Yossef
Published: February 2021

We present multiband Hubble Space Telescope imaging of the calcium-rich supernova (SN) SN 2019ehk at 276-389 days after explosion. These observations represent the latest B-band to near-IR photometric measurements of a calcium-rich transient to date and allow for the first opportunity to analyze the late-time bolometric evolution of an object in this observational SN class. We find that the late-time bolometric light curve of SN 2019ehk can be described predominantly through the radioactive decay of 56Co for which we derive a mass of M(56Co) = (2.8 ± 0.1) × 10−2
M
⊙. Furthermore, the rate of decline in bolometric luminosity requires the leakage of γ-rays on timescale t

γ
= 53.9 ± 1.30 days, but we find no statistical evidence for incomplete positron trapping in the SN ejecta. While our observations cannot constrain the exact masses of other radioactive isotopes synthesized in SN 2019ehk, we estimate a mass ratio limit of M(57Co)/M(56Co) ≤ 0.030. This limit is consistent with the explosive nucleosynthesis produced in the merger of low-mass white dwarfs, which is one of the favored progenitor scenarios in early-time studies of SN 2019ehk.
Constraint on
G˙/G
from Orbital Timing
Authors: Gupta Rajendra P.
Published: February 2021

Constraints on the variation of the gravitational constant G have been obtained by many observers using different methods, the most reliable and stringent being those based on the orbital timing of bodies in the solar system and binary pulsars. We show that the constraints determined from orbital timing are on

G

˙

/

G
−
3

c

˙

/

c

rather than on

G

˙

/

G

when the speed of light c is also considered to be varying. Increasingly tighter constraint on

G

˙

/

G

from these observations are possibly due to

G

˙

/

G
−
3

c

˙

/

c
=
0

. This relationship between G and c was determined in a previous work by fitting the supernovae 1a data using the relativistically covariant cosmological model with varying

c
,
G

and cosmological constant Λ.
Transient Terrestrial Trojans: Comparative Short-term Dynamical Evolution of 2010 TK7 and 2020 XL5
Authors: de la Fuente Marcos Carlos , de la Fuente Marcos Raúl
Published: February 2021

The Trojan asteroids of Mars and Jupiter are long-term stable, those of Earth are expected to be just transient companions. The first Trojan of our planet, 2010 TK7, was discovered in 2010 and its resonant state was found to be transient. Here, we provide a preliminary assessment of the current dynamical status and short-term orbital evolution of 2020 XL5, a recently discovered near-Earth asteroid that might be the second known representative of this elusive population. Our calculations show that the current orbit determination of 2010 TK7 is consistent with that of a robust, present-day, yet transient, L4 Earth Trojan. In sharp contrast, the current orbit determination of 2020 XL5 is still too uncertain and its orbital evolution too chaotic to confirm a current Trojan engagement with Earth, although the nominal orbit shows such a behavior. More observations are required to provide a conclusive answer.
Notes on leaf micromorphology of the rare herbaceous bamboo Buergersiochloa bambusoides Pilg. (Olyreae, Poaceae) from New Guinea and its taxonomic implications
Authors: Lima Jamile F. , Leite Kelly Regina B. , Clark Lynn G. , Oliveira Reyjane P.
Published: February 2021

We present notes on the leaf micromorphology of Buergersiochloa bambusoides, a rare species from New Guinea and included in Buergersiochloinae, one of three subtribes of the herbaceous bamboos (tribe Olyreae). We used scanning electron microscopy and light microscopy to analyze the microcharacters of both adaxial and abaxial leaf surfaces. Within the Olyreae, saddle-shaped silica bodies in both the costal and intercostal zones are considered unique to Buergersiochloinae. Simple, circular and very small papillae are observed on the adaxial surface, and for the first time, branched papillae on the abaxial surface are observed in B. bambusoides. On the abaxial surface, there are papillae on long cells associated with the stomatal complexes. Bicellular microhairs are the only trichomes present and they are found almost exclusively on the abaxial surface. The saddle-shaped silica bodies are the most taxonomically important among the microcharacters observed on the leaf surface of B. bambusoides.
Glacier Strait
Authors:   Canada Surveys and Mapping Branch
Published: February 2021

"The Glacier Atlas of Canada is a collection of maps produced as part of the Canadian Glacier Inventory Project. This project was initiated as part of Canada's contribution to the International Hydrological Decade (1965 to 1974). Although publication of this map
series was suspended in the mid-seventies and gaps remain to be filled for some coverage areas, what has been created for this series thus far should prove useful in some aspects of glacier research. These map plates display glaciers and glacier regions. Glaciers are denoted by a numbering system,
which is keyed to Canadian glacier inventory data. Perennial ice and snow, hydrological units and major drainage divides are also denoted."
Raanes and Svendsen Peninsulas
Authors:   Canada Surveys and Mapping Branch
Published: February 2021

"The Glacier Atlas of Canada is a collection of maps produced as part of the Canadian Glacier Inventory Project. This project was initiated as part of Canada's contribution to the International Hydrological Decade (1965 to 1974). Although publication of this map
series was suspended in the mid-seventies and gaps remain to be filled for some coverage areas, what has been created for this series thus far should prove useful in some aspects of glacier research. These map plates display glaciers and glacier regions. Glaciers are denoted by a numbering system,
which is keyed to Canadian glacier inventory data. Perennial ice and snow, hydrological units and major drainage divides are also denoted."
Fosheim Peninsula
Authors:   Canada Surveys and Mapping Branch
Published: February 2021

"The Glacier Atlas of Canada is a collection of maps produced as part of the Canadian Glacier Inventory Project. This project was initiated as part of Canada's contribution to the International Hydrological Decade (1965 to 1974). Although publication of this map
series was suspended in the mid-seventies and gaps remain to be filled for some coverage areas, what has been created for this series thus far should prove useful in some aspects of glacier research. These map plates display glaciers and glacier regions. Glaciers are denoted by a numbering system,
which is keyed to Canadian glacier inventory data. Perennial ice and snow, hydrological units and major drainage divides are also denoted."
Devon Island
Authors:   Canada Surveys and Mapping Branch
Published: February 2021

"The Glacier Atlas of Canada is a collection of maps produced as part of the Canadian Glacier Inventory Project. This project was initiated as part of Canada's contribution to the International Hydrological Decade (1965 to 1974). Although publication of this map
series was suspended in the mid-seventies and gaps remain to be filled for some coverage areas, what has been created for this series thus far should prove useful in some aspects of glacier research. These map plates display glaciers and glacier regions. Glaciers are denoted by a numbering system,
which is keyed to Canadian glacier inventory data. Perennial ice and snow, hydrological units and major drainage divides are also denoted."
Devon Ice Cap - North
Authors:   Canada Surveys and Mapping Branch
Published: February 2021

"The Glacier Atlas of Canada is a collection of maps produced as part of the Canadian Glacier Inventory Project. This project was initiated as part of Canada's contribution to the International Hydrological Decade (1965 to 1974). Although publication of this map
series was suspended in the mid-seventies and gaps remain to be filled for some coverage areas, what has been created for this series thus far should prove useful in some aspects of glacier research. These map plates display glaciers and glacier regions. Glaciers are denoted by a numbering system,
which is keyed to Canadian glacier inventory data. Perennial ice and snow, hydrological units and major drainage divides are also denoted."
Axel Heiberg Island
Authors:   Canada Surveys and Mapping Branch
Published: February 2021

"The Glacier Atlas of Canada is a collection of maps produced as part of the Canadian Glacier Inventory Project. This project was initiated as part of Canada's contribution to the International Hydrological Decade (1965 to 1974). Although publication of this map
series was suspended in the mid-seventies and gaps remain to be filled for some coverage areas, what has been created for this series thus far should prove useful in some aspects of glacier research. These map plates display glaciers and glacier regions. Glaciers are denoted by a numbering system,
which is keyed to Canadian glacier inventory data. Perennial ice and snow, hydrological units and major drainage divides are also denoted."
Axel Heiberg Island - Southern
Authors:   Canada Surveys and Mapping Branch
Published: February 2021

"The Glacier Atlas of Canada is a collection of maps produced as part of the Canadian Glacier Inventory Project. This project was initiated as part of Canada's contribution to the International Hydrological Decade (1965 to 1974). Although publication of this map
series was suspended in the mid-seventies and gaps remain to be filled for some coverage areas, what has been created for this series thus far should prove useful in some aspects of glacier research. These map plates display glaciers and glacier regions. Glaciers are denoted by a numbering system,
which is keyed to Canadian glacier inventory data. Perennial ice and snow, hydrological units and major drainage divides are also denoted."
Baffin Island
Authors:   Canada Surveys and Mapping Branch
Published: February 2021

"The Glacier Atlas of Canada is a collection of maps produced as part of the Canadian Glacier Inventory Project. This project was initiated as part of Canada's contribution to the International Hydrological Decade (1965 to 1974). Although publication of this map
series was suspended in the mid-seventies and gaps remain to be filled for some coverage areas, what has been created for this series thus far should prove useful in some aspects of glacier research. These map plates display glaciers and glacier regions. Glaciers are denoted by a numbering system,
which is keyed to Canadian glacier inventory data. Perennial ice and snow, hydrological units and major drainage divides are also denoted."
Coronation Fiord
Authors:   Canada Surveys and Mapping Branch
Published: February 2021

"The Glacier Atlas of Canada is a collection of maps produced as part of the Canadian Glacier Inventory Project. This project was initiated as part of Canada's contribution to the International Hydrological Decade (1965 to 1974). Although publication of this map
series was suspended in the mid-seventies and gaps remain to be filled for some coverage areas, what has been created for this series thus far should prove useful in some aspects of glacier research. These map plates display glaciers and glacier regions. Glaciers are denoted by a numbering system,
which is keyed to Canadian glacier inventory data. Perennial ice and snow, hydrological units and major drainage divides are also denoted."
Padle Fiord
Authors:   Canada Surveys and Mapping Branch
Published: February 2021

"The Glacier Atlas of Canada is a collection of maps produced as part of the Canadian Glacier Inventory Project. This project was initiated as part of Canada's contribution to the International Hydrological Decade (1965 to 1974). Although publication of this map
series was suspended in the mid-seventies and gaps remain to be filled for some coverage areas, what has been created for this series thus far should prove useful in some aspects of glacier research. These map plates display glaciers and glacier regions. Glaciers are denoted by a numbering system,
which is keyed to Canadian glacier inventory data. Perennial ice and snow, hydrological units and major drainage divides are also denoted."
Hoare Bay
Authors:   Canada Surveys and Mapping Branch
Published: February 2021

"The Glacier Atlas of Canada is a collection of maps produced as part of the Canadian Glacier Inventory Project. This project was initiated as part of Canada's contribution to the International Hydrological Decade (1965 to 1974). Although publication of this map
series was suspended in the mid-seventies and gaps remain to be filled for some coverage areas, what has been created for this series thus far should prove useful in some aspects of glacier research. These map plates display glaciers and glacier regions. Glaciers are denoted by a numbering system,
which is keyed to Canadian glacier inventory data. Perennial ice and snow, hydrological units and major drainage divides are also denoted."
Oldman River
Authors:   Canada Surveys and Mapping Branch
Published: February 2021

"The Glacier Atlas of Canada is a collection of maps produced as part of the Canadian Glacier Inventory Project. This project was initiated as part of Canada's contribution to the International Hydrological Decade (1965 to 1974). Although publication of this map
series was suspended in the mid-seventies and gaps remain to be filled for some coverage areas, what has been created for this series thus far should prove useful in some aspects of glacier research. These map plates display glaciers and glacier regions. Glaciers are denoted by a numbering system,
which is keyed to Canadian glacier inventory data. Perennial ice and snow, hydrological units and major drainage divides are also denoted."
North Saskatchewan River
Authors:   Canada Surveys and Mapping Branch
Published: February 2021

"The Glacier Atlas of Canada is a collection of maps produced as part of the Canadian Glacier Inventory Project. This project was initiated as part of Canada's contribution to the International Hydrological Decade (1965 to 1974). Although publication of this map
series was suspended in the mid-seventies and gaps remain to be filled for some coverage areas, what has been created for this series thus far should prove useful in some aspects of glacier research. These map plates display glaciers and glacier regions. Glaciers are denoted by a numbering system,
which is keyed to Canadian glacier inventory data. Perennial ice and snow, hydrological units and major drainage divides are also denoted."
Annual snowfall
Authors:   Canada Surveys and Mapping Branch
Published: February 2021

The map shows the annual snowfall (in centimetres) based on the 30-year period 1941-1970. Snowfall is measured by inserting a ruler into the new snow at several points to obtain its depth and to estimate the degree of drifting or scouring that has occurred. The
water equivalent of snowfall for most climatologically stations is estimated by simply assuming the freshly fallen snow has a density of 0.10 gram per cubic centimetre. On the average, this is a sound approximation over large parts of the country, but variations from 0.05 to 0.15 are common from
storm to storm, and in the drier regions the average density is probably closer to 0.08 gram per cubic centimetre. Since 1961 the Nipher shielded snow gauge has been used at principal stations to derive the water equivalent of snowfalls. Snow collected in the gauge is melted to obtain this value. At
remote stations snowfall is measured in terms of water equivalent by automatic and storage gauges, such as the Fischer and Porter Gauge and the Sacramento
Depth, duration and frequency of point rainfall - 24-hour rainfall for 2-year, 5-year, 10 year and 25-year return periods
Authors:   Canada Surveys and Mapping Branch
Published: February 2021

The plate contains four maps of 24 hour rainfalls (in millimetres) for a 2 year return period, a 5 year return period, a 10 year return period and a 25 year return period. Each map has a detailed inset of the Vancouver area. These four maps were not analyzed for
the mountainous parts of Canada in British Columbia and the Yukon because of the limited number of stations, the non-representative nature of the valley stations and the variability of precipitation owing to the orographic effects. From the incomplete data, it is impossible to draw accurate isolines
of short duration rainfall amounts on maps of national scale. Point values for all stations west of the Rocky Mountain range and in the Yukon have been plotted for durations of less than 24 hours. For the Vancouver metropolitan area, recording rain gauges have been in operation for several years.
For some of these stations point rainfall data have been plotted on inset maps. The density of climatological stations varies widely as does population
Mean July daily temperature
Authors:   Canada Surveys and Mapping Branch
Published: February 2021

The map shows the mean daily temperatures based on the 30-year period 1941-1970 for the warmest month in Canada. Although, the most direct and the most intense incoming solar radiation occurs in June, there is a lag in the warming of the Earths surface. As a
result the warmest month in Canada is normally July. The lowest mean July temperatures are below 5 degrees Celsius and are located in the Arctic Islands. The highest mean July daily temperatures are above 20 degrees Celsius and are located in southern Ontario, southern Quebec, south of Winnipeg,
Manitoba, the Medicine Hat area of Alberta and in some valleys in the interior of British Columbia. Generally, the mean increases from north to south, from 2.5 to 22.5 degrees Celsius. In British Columbia, the warmer temperatures are in river basins of the Cordillera. In fact, all valleys of the
Cordillera are warmer than the surrounding slopes. In winter, however, atmospheric inversions may result in valleys being warmer or colder than higher terrain. T
Groundwater observation wells
Authors:   Canada Surveys and Mapping Branch
Published: February 2021

The map shows the location of the six hydrogeological regions in Canada and the location of observation wells. The terrain composition is also shown on the map, which includes crystalline rocks, mixed crystalline rocks, folded sedimentary rocks and flat lying
sedimentary rocks. The southern limit of continuous permafrost zone and the limit of the discontinuous permafrost zone appear on the map. Canada has been divided into six hydrogeological regions on the basis of similarities of geology, climate, and topography. These six hydrogeological regions are
(1) the Appalachians, covering the area of New Brunswick, Prince Edward Island, Nova Scotia, Newfoundland, and the Gaspé and Eastern Townships of Quebec; (2) the St. Lawrence Lowlands, covering Anticosti Island, the extreme southern area of Quebec, and the southern part of Ontario; (3) the
Canadian Shield, lying north of the St. Lawrence Lowlands and extending northward to a line joining the north end of Lake Winnipeg to Anticosti Island; (4) the Inte
Water balance - derived precipitation and evapotranspiration
Authors:   Canada Surveys and Mapping Branch
Published: February 2021

The map shows isolines for the annual precipitation and the annual evapotranspiration (in millimetres). Water is normally supplied by precipitation and lost through the processes of evapotranspiration and runoff or it may remain as surface or subsurface storage.
Over long periods, generally several years or more, changes in water storage for any particular region may be neglected, and the precipitation (P) is balanced by evapotranspiration (E) and runoff (N). The concept of a water balance was first introduced in the literature by Thornthwaite in 1944 as a
means of calculating evapotranspiration. Since that time, the water balance concept has been used in a variety of ways; herein it is viewed conceptually by the following equation: P = N + E. In this form, the water balance equation can serve a dual purpose. It can provide estimates of any of the
components P, N, or E as long as the other two are known, or it can serve as a check when each of the components has been measured independently. The der
Characterization of shallow aquifers and assessment of potential impacts of oil and gas development activities on these aquifers in the Fox Creek area (AB)
Authors: Rivard C
Published: February 2021

A multidisciplinary and multi-institutional project was initiated in the Fox Creek area (west-central Alberta) in April 2019 to study environmental impacts of hydrocarbon development activities. The initial objective was to specifically study potential impacts on
shallow groundwater. However, different Sectors within NRCan later identified the Fox Creek area as a region of interest for developing regional cumulative effects evaluation methods in support of new impact assessment legislation. Therefore, the project scope is now much larger and includes studies
on vegetation, forest, snow cover, wetlands, landscape evolution and woodland caribou habitat. The project involves many collaborators from the federal and provincial governments, and academia. This project is supported by both the GGP and EGP programs and is also funded by the Cumulative Effects
initiative.