bluuebunny/crossref_metadata_2025_split huggingface dataset:
VR CCD Photometry of Variable Stars in the Globular Cluster NGC 4147
Authors: Lata Sneh , Pandey A. K. , Pandey J. C. , Yadav R. K. S. , Pandey Shashi B. , Gupta Aashish , Bangia Tarun , Chand Hum , Jaiswar Mukesh K. , Joshi Yogesh C. , Joshi Mohit , Kumar Brijesh , Kumar T. S. , Medhi Biman J. , Misra Kuntal , Nanjappa Nandish , Pant Jaysreekar , Purushottam  , Reddy B. Krishna , Sahu Sanjit , Sharma Saurabh , Uddin Wahab , Yadav Shobhit 
Published: July 2019

Abstract
We present results of a search for variable stars in a region of the globular cluster NGC 4147 based on photometric observations with a 4K × 4K CCD imager mounted at the axial port of the recently installed 3.6 m Devasthal optical telescope at Aryabhatta Research Institute of Observational Sciences, Nainital, India. We performed time series photometry of NGC 4147 in the V and R bands, and identified 42 periodic variables in the region of NGC 4147, 28 of which have been detected for the first time. Seventeen variable stars are located within the half-light radius ≲0.′48, of which 10 stars are newly identified variables. Two of the 10 variables are located within the core radius ≲0.′09. Based on their location in the V/(V − R) color–magnitude diagram and variability characteristics, seven, eight, five, and one newly identified probable member variables are classified as RRc, EA/E, EW, and SX Phe, respectively. The metallicity of NGC 4147 estimated from the light curves of RRab and RRc stars with the help of Fourier decomposition is found to be characteristic of Oosterhoff II. The distance derived using the light curves of RRab stars is consistent with that obtained from the observed V/(V − R) color–magnitude diagram.
The G305 Star-forming Region. I. Newly Classified Hot Stars*
Authors: Borissova Jura , Roman-Lopes Alexandre , Covey Kevin , Medina Nicolas , Kurtev Radostin , Roman-Zuniga Carlos , Kuhn M. A. , Contreras Peña Carlos , Lucas Philip , Ramirez Alegria Sebastian , Minniti Dante , Kounkel Marina , Stringfellow Guy , Barbá Rodolfo H. , Suárez Genaro 
Published: July 2019

Abstract
The relatively nearby star-forming complex G305 is one of the most luminous H ii regions in the Galaxy, and it contains several sites and epochs of star formation. Using a combination of near-infrared photometry from “Vista Variables in Via Lactea” ESO Large Public Survey, SDSS-IV APOGEE-2 spectra, and Gaia DR2 photometry and astrometry, we report on 29 OB type, Wolf–Rayet, and emission-line stars, 18 of which are newly classified. Most of these hot stars belongs to the main sequence, although some stars of class I are also proposed. The mean radial velocity is RV = −41.8

. The average spectroscopic distance is 3.2 ± 1.6 kpc, while the Gaia DR2 average distance is 3.7 ± 1.8 kpc. Eight objects show light-curve variations with amplitudes greater than 0.5 mag in the K

S
band.
Nucleosynthetic Sr–Nd Isotope Correlations in Chondrites: Evidence for Nebular Thermal Processing and Dust Transportation in the Early Solar System
Authors: Fukai Ryota , Yokoyama Tetsuya 
Published: July 2019

Abstract
We conducted high-precision Sr and Nd isotopic measurements in bulk chondrites using a complete sample digestion technique. Our new data indicate that enstatite and ordinary chondrites possess uniform and small, but resolvable, Sr and Nd isotopic deviations from terrestrial rocks. In contrast, the Sr isotope ratios varied across different classes of carbonaceous chondrites (CM, CO, and CV). The deviation of data from the s-process mixing line in Sr–Nd isotopic space likely resulted from the incorporation of calcium-aluminum-rich inclusions (CAIs) into carbonaceous chondrite parent bodies. Planetary-scale Sr and Nd isotopic heterogeneities among terrestrial rocks, enstatite, ordinary chondrites, and CAI-subtracted carbonaceous chondrites suggest a heterogeneous distribution of s-process-enriched materials in the early solar system, probably caused by nebular thermal processing. The observed Sr and Nd isotopic variation across the CAI-subtracted carbonaceous chondrites cannot be explained solely by nebular thermal processing, but is likely attributable to s-process-depleted silicate grains that repeatedly circulated among the early solar system. These grains were transferred and incorporated at varying degrees into the formation region of the parent bodies of individual carbonaceous chondrites.
Near-infrared Spectroscopy of Galaxies During Reionization: Measuring C iii] in a Galaxy at z = 7.5
Authors: Hutchison Taylor A. , Papovich Casey , Finkelstein Steven L. , Dickinson Mark , Jung Intae , Zitrin Adi , Ellis Richard , Malhotra Sangeeta , Rhoads James , Roberts-Borsani Guido , Song Mimi , Tilvi Vithal 
Published: July 2019

Abstract
We present Keck/MOSFIRE H-band spectroscopy targeting C iii] λ1907, 1909 in a z = 7.5056 galaxy previously identified via Lyα emission. We detect strong line emission at

with a line flux of (2.63 ± 0.52) × 10−18 erg s−1 cm−2. We tentatively identify this line as [C iii] λ1907, but we are unable to detect C iii] λ1909 owing to sky emission at the expected location. This gives a galaxy systemic redshift,

, with a velocity offset to Lyα of

= 88 ± 27 km s−1. The ratio of combined C iii]/Lyα is 0.30–0.45, one of the highest values measured for any z > 2 galaxy. We do not detect Si iii] λλ1883, 1892, and place an upper limit on Si iii]/C iii] < 0.35 (2σ). Comparing our results to photoionization models, the C iii] equivalent width (W
C iii] = 16.23 ± 2.32 Å), low Si iii]/C iii] ratio, and high implied [O iii] equivalent width (from the Spitzer/IRAC [3.6]–[4.5] ≃ 0.8 mag color) require subsolar metallicities (Z ≃ 0.1–0.2 Z
⊙) and a high ionization parameter, log U ≳ −1.5. These results favor models that produce higher ionization, such as the bpass models for the photospheres of high-mass stars, and that include both binary stellar populations and/or an IMF that extends to 300 M
⊙. The combined C iii] equivalent width and [3.6]–[4.5] color are more consistent with ionization from young stars than active galactic nuclei (AGNs); however, we cannot rule out ionization from a combination of an AGN and young stars. We make predictions for James Webb Space Telescope spectroscopy using these different models, which will ultimately test the nature of the ionizing radiation in this source.
The Payne: Self-consistent ab initio Fitting of Stellar Spectra
Authors: Ting 丁 Yuan-Sen 源森 , Conroy Charlie , Rix Hans-Walter , Cargile Phillip 
Published: July 2019

Abstract
We present The Payne, a general method for the precise and simultaneous determination of numerous stellar labels from observed spectra, based on fitting physical spectral models. The Payne combines a number of important methodological aspects: it exploits the information from much of the available spectral range; it fits all labels (stellar parameters and elemental abundances) simultaneously; it uses spectral models, where the structure of the atmosphere and the radiative transport are consistently calculated to reflect the stellar labels. At its core The Payne has an approach to accurate and precise interpolation and prediction of the spectrum in high-dimensional label space that is flexible and robust, yet based on only a moderate number of ab initio models (

for 25 labels). With a simple neural-net-like functional form and a suitable choice of training labels, this interpolation yields a spectral flux prediction good to 10−3 rms across a wide range of T
eff and

(including dwarfs and giants). We illustrate the power of this approach by applying it to the APOGEE DR14 data set, drawing on Kurucz models with recently improved line lists: without recalibration, we obtain physically sensible stellar parameters as well as 15 elemental abundances that appear to be more precise than the published APOGEE DR14 values. In short, The Payne is an approach that for the first time combines all these key ingredients, necessary for progress toward optimal modeling of survey spectra; and it leads to both precise and accurate estimates of stellar labels, based on physical models and without “recalibration.” Both the codes and catalog are made publicly available online.
Quasi-periodicity of Supermassive Binary Black Hole Accretion Approaching Merger
Authors: Bowen Dennis B. , Mewes Vassilios , Noble Scott C. , Avara Mark , Campanelli Manuela , Krolik Julian H. 
Published: July 2019

Abstract
In this paper we continue the first ever study of magnetized mini-disks coupled to circumbinary accretion in a supermassive binary black hole (SMBBH) approaching merger reported in Bowen et al. We extend this simulation from 3 to 12 binary orbital periods. We find that relativistic SMBBH accretion acts as a resonant cavity, where quasi-periodic oscillations tied to the frequency at which the black hole’s (BH’s) orbital phase matches a nonlinear m = 1 density feature, or “lump,” in the circumbinary accretion disk permeate the system. The rate of mass accretion onto each of the mini-disks around the BHs is modulated at the beat frequency between the binary frequency and the lump’s mean orbital frequency, i.e.,

, while the total mass accretion rate of this equal-mass binary is modulated at two different frequencies,

and

. The instantaneous rotation rate of the lump itself is also modulated at two frequencies close to the modulation frequencies of the total accretion rate,

and

. Because of the compact nature of the mini-disks in SMBBHs approaching merger, the inflow times within the mini-disks are comparable to the period on which their mass supply varies, so that their masses—and the accretion rates they supply to their BHs—are strongly modulated at the same frequency. In essence, the azimuthal symmetry of the circumbinary disk is broken by the dynamics of orbits near a binary, and this m = 1 asymmetry then drives quasi-periodic variation throughout the system, including both accretion and disk-feeding. In SMBBHs approaching merger, such time variability could introduce distinctive, increasingly rapid, fluctuations in their electromagnetic emission.
Observing Current Sheet Formation Forced by Non-radial Rotating Motion of Mini-filaments
Authors: Chen Hechao , Yang Jiayan , Duan Yadan , Ji Kaifan 
Published: July 2019

Abstract
In this paper, we study two externally forced magnetic reconnection events near NOAA active region 12494 for their current sheet (CS) formation. In both events, small-scale reconnection happened between mini-filaments and other preexisting magnetic fields. Initially, mini-filaments underwent obvious non-radial rotating motion due to their loss of equilibrium. With their clockwise/anti-clockwise rotation, the axial fluxes of the mini-filaments slowly came to squeeze the anti-parallel ambient fields, leading to an X-shaped structure. As the squeezing effect strengthened, CS regions gradually formed and grew in length, with a temperature around 1.8 MK. Afterward, clear cusp regions, plasma heating (∼5 MK), and newborn magnetic structures came to be in sequence. Finally, mini-filaments erupted in a complex fashion due to the involvement of external reconnection. Based on the multiwavelength imaging observations, the apparent thickness/length, temperature/emission of the CS regions and their related plasma flows are carefully analyzed. Their reconnection rates are roughly estimated as 0.01–0.06 and 0.01–0.02. In particular, a chain of high-speed plasmoid ejections was detected along with a set of the reconnected field lines in Event1, implying the onset of tearing-mode instability inside its CS region. These observations indicate that non-radial rotating motion of filaments can serve as external flows to drive reconnection, and also provide a basic scenario of CS formation within small-scale magnetic reconnetion processes.
Molecular Gas Density Measured with H2CO and CS toward a Spiral Arm of M51
Authors: Nishimura Yuri , Watanabe Yoshimasa , Harada Nanase , Kohno Kotaro , Yamamoto Satoshi 
Published: July 2019

Abstract
Observations of various molecular lines toward a disk region of a nearby galaxy are now feasible, and they are being employed as diagnostic tools to study star formation activities there. However, the spatial resolution attainable for a nearby galaxy with currently available radio telescopes is 10–1000 pc, which is much larger than the scales of individual star-forming regions and molecular-cloud cores. Hence, it is of fundamental importance to elucidate which part of an interstellar medium such spatially unresolved observations are tracing. Here we present sensitive measurements of the H2CO (

) line at 72 GHz toward giant molecular clouds (GMCs) in the spiral arm of M51 using the NRO 45 m and IRAM 30 m telescopes. In conjunction with the previously observed H2CO (202 − 101) and CS (2 − 1 and 3 − 2) lines, we derive the H2 density of the emitting regions to be (0.6–2.6) × 104 cm−3 and (2.9–12) × 104 cm−3 for H2CO and CS, respectively, by the non-LTE analyses, where we assume the source size of 0.8–1 kpc and the gas kinetic temperature of 10–20 K. The derived H2 density indicates that the emission of H2CO and CS is not localized to star-forming cores, but is likely distributed over an entire region of GMCs. Such widespread distributions of H2CO and CS are also supported by models assuming lognormal density distributions over the 1 kpc region. Thus, contributions from the widespread less dense components should be taken into account for interpretation of the molecular emission observed with a GMC-scale resolution. The different H2 densities derived for H2CO and CS imply their different distributions. We discuss these differences in terms of the formation processes of H2CO and CS.
Genus Statistic Applied to the X-Ray Remnant of SN 1572: Clues to the Clumpy Ejecta Structure of Type Ia Supernovae
Authors: Sato Toshiki , Hughes John P. , Williams Brian J. , Morii Mikio 
Published: July 2019

Abstract
Clumpy structures are a common feature in X-ray images of young Type Ia supernova remnants (SNRs). Although the precise origin of such clumps remains unclear, there are three generic possibilities: clumpiness imposed during the explosion, hydrodynamic instabilities that act during the remnant’s evolution, and preexisting structures in the ambient medium. In this article we focus on discriminating between clumping distributions that arise from the explosion and those from the remnant’s evolution using existing 3D hydrodynamical simulations. We utilize the genus statistic for this discrimination, applying it to the simulations and to Chandra X-ray observations of the well-known SN Ia remnant of SN 1572 (Tycho’s SNR). The genus curve of Tycho’s SNR strongly indicates a skewed non-Gaussian distribution of the ejecta clumps and is similar to the genus curve for the simulation with initially clumped ejecta. In contrast, the simulation of perfectly smooth ejecta where clumping arises from the action of hydrodynamic instabilities produced a genus curve that is similar to a random Gaussian field, but disagrees strongly with the genus curve of the observed image. Our results support a scenario in which the observed structure of SN Ia remnants arises from initial clumpiness in the explosion.
Radial Velocities of Low-mass Candidate TWA Members
Authors: Kidder Benjamin , Mace Gregory , Sokal Kimberly , Lopez Ricardo , Jaffe Daniel 
Published: July 2019

Abstract
Nearby young moving groups provide unique samples of similar age stars for testing the evolution of physical properties. Incomplete and/or incorrect group membership classifications reduce the usefulness of the group, which we assume to be coeval. With near-infrared spectra of two candidate members of the TW Hya Association, 2MASS J12354615−4115531 (TWA 46) and 2MASS J12371238−4021480 (TWA 47), we test their membership by adding radial velocity measurements to the literature. We find that 2MASS J12354615−4115531 is a close spectroscopic binary system with a center-of-mass radial velocity of −6.5 ± 3.9 km s−1. This radial velocity and a Gaia parallax produces a TW Hydra association (TWA) membership probability of 41.9% using the Banyan Σ tool for 2MASS J12354615−4115531. The spectrum of 2MASS J12371238−4021480 shows that it appears to be a single star with a radial velocity consistent with the TW Hya Association and a membership probability of 99.5%. The reduced probability of TWA 46 as a true member of TWA highlights the importance of high-resolution, near-infrared spectra in validating low-mass moving group members.
Modules for Experiments in Stellar Astrophysics (MESA): Pulsating Variable Stars, Rotation, Convective Boundaries, and Energy Conservation
Authors: Paxton Bill , Smolec R. , Schwab Josiah , Gautschy A. , Bildsten Lars , Cantiello Matteo , Dotter Aaron , Farmer R. , Goldberg Jared A. , Jermyn Adam S. , Kanbur S. M. , Marchant Pablo , Thoul Anne , Townsend Richard H. D. , Wolf William M. , Zhang Michael , Timmes F. X. 
Published: July 2019

Abstract
We update the capabilities of the open-knowledge software instrument Modules for Experiments in Stellar Astrophysics (MESA). RSP is a new functionality in MESAstar that models the nonlinear radial stellar pulsations that characterize RR Lyrae, Cepheids, and other classes of variable stars. We significantly enhance numerical energy conservation capabilities, including during mass changes. For example, this enables calculations through the He flash that conserve energy to better than 0.001%. To improve the modeling of rotating stars in MESA, we introduce a new approach to modifying the pressure and temperature equations of stellar structure, as well as a formulation of the projection effects of gravity darkening. A new scheme for tracking convective boundaries yields reliable values of the convective core mass and allows the natural emergence of adiabatic semiconvection regions during both core hydrogen- and helium-burning phases. We quantify the parallel performance of MESA on current-generation multicore architectures and demonstrate improvements in the computational efficiency of radiative levitation. We report updates to the equation of state and nuclear reaction physics modules. We briefly discuss the current treatment of fallback in core-collapse supernova models and the thermodynamic evolution of supernova explosions. We close by discussing the new MESA Testhub software infrastructure to enhance source code development.
Can the Superposition of Evaporative Flows Explain Broad Fe xxi Profiles during Solar Flares?
Authors: Polito Vanessa , Testa Paola , De Pontieu Bart 
Published: July 2019

Abstract
The observation of the high-temperature (≳10 MK) Fe xxi 1354.1 Å line with the Interface Region Imaging Spectrograph has provided significant insights into the chromospheric evaporation process in flares. In particular, the line is often observed to be completely blueshifted, in contrast to previous observations at lower spatial and spectral resolution, and in agreement with predictions from theoretical models. Interestingly, the line is also observed to be mostly symmetric and significantly broader than expected from thermal motions (assuming the peak formation temperature of the ion is in equilibrium). One popular interpretation for the nonthermal broadening is the superposition of flows from different loop strands. In this work, we test this scenario by forward-modeling the Fe xxi line profile assuming different possible observational scenarios using hydrodynamic simulations of multi-thread flare loops with the 1D RADYN code. Our results indicate that the superposition of flows alone cannot easily reproduce both the symmetry and the significant broadening of the line and that some other physical process, such as turbulence, or a much larger ion temperature than previously expected, likely needs to be invoked in order to explain the observed profiles.
Comparison of naproxen and Gelofen for Pain relief in lower third molar surgery: A single-blinded randomized clinical trial
Authors: Aliabadi Ehsan , Tavanafar Saeid , Hayati Mehdi 
Published: July 2019

Abstract
Objectives: Third molar surgeries are a routine procedure in oral and maxillofacial surgery and its associated pain is bothersome to patients. The purpose of this study was to compare the analgesic effect of Gelofen and naproxen in lower third molar surgery. Materials and Methods: A single-blinded randomized clinical trial was designed, and patients were randomly allocated into four groups (n = 20 cases in each group): pre-Gelofen group: 400 mg Gelofen 30 min preoperative and continuing every 6 h, Gelofen group: 400 mg Gelofen immediately postoperative and continuing every 6 h, pre-naproxen group: 500 mg naproxen 30 min preoperative and every 8 h, and naproxen group: 500 mg naproxen immediately postoperative and every 8 h. The pain intensity was recorded using the visual analog scale at 2, 6, 12, and 24 h after surgery. Results: Pain intensity decreased in a linear pattern in all groups after 2, 6, 12, and 24 h. In pre-naproxen group, pain decreased suddenly between 2 and 6 h, but after 6 h, pain relief was slower than other groups. The mean pain intensity at 2 h postoperative for the pre-naproxen group was significantly lower than Gelofen group, and at 6 h, it was less than all other groups. At 12 and 24 h after surgery, pain intensity in all groups was similar except for the Gelofen group. Conclusion: Under limitation of the present study, preoperative intake of naproxen showed more effective pain relief than other groups.
Delivering on the Promise: Exploring Training Characteristics and Graduate Career Pursuits of Primary Care Internal Medicine Residency Programs and Tracks
Authors: Klein Robin , Alonso Samantha , Anderson Caitlin , Vaidya Akanksha , Chams Nour , Kurl Anu , Lim Katryna , Taylor Caitlin , Higgins Stacy M. 
Published: July 2019

ABSTRACT

Background
Specialized primary care internal medicine (PC IM) residency programs and tracks aim to provide dedicated PC training. How programs deliver this is unclear.

Objective
We explored how PC IM programs and tracks provide ambulatory training.

Methods
We conducted a cross-sectional survey from 2012 to 2013 of PC IM program and track leaders via a search of national databases and program websites. We reported PC IM curricular content, clinical experiences, and graduate career pursuits, and assessed correlation between career pursuits and curricular content and clinical experiences.

Results
Forty-five of 70 (64%) identified PC IM programs and tracks completed the survey. PC IM programs provide a breadth of curricular content and clinical experiences, including a mean 22.8 weeks ambulatory training and a mean 69.4 continuity clinics per year. Of PC IM graduates within 5 years, 55.8% pursue PC or general internal medicine (GIM) careers and 23.1% pursue traditional subspecialty fellowship training. Curricular content and clinical experiences correlate weakly with career choices. PC IM graduates pursuing PC or GIM careers correlated with ambulatory rotation in women's health (correlation coefficient [rho] = 0.36, P = .034) and mental health (rho = 0.38, P = .023) and curricular content in teaching and medical education (rho = 0.35, P = .035). PC IM graduates pursuing subspecialty fellowship negatively correlated with curricular content in leadership and teams (rho = -0.48, P = .003) and ambulatory training time (rho = -0.38, P = .024).

Conclusions
PC IM programs and tracks largely deliver on the promise to provide PC training and education and produce graduates engaged in PC and GIM.