bluuebunny/crossref_metadata_2025_split huggingface dataset:
DETERMINING THE AGE OF THE KEPLER OPEN CLUSTER NGC 6819 WITH A NEW TRIPLE SYSTEM AND OTHER ECLIPSING BINARY STARS*
Authors: Brewer Lauren N. , Sandquist Eric L. , Mathieu Robert D. , Milliman Katelyn , Geller Aaron M. , Jeffries, Jr. Mark W. , Orosz Jerome A. , Brogaard Karsten , Platais Imants , Bruntt Hans , Grundahl Frank , Stello Dennis , Frandsen Søren 
Published: February 2016

ABSTRACT
As part of our study of the old (∼2.5 Gyr) open cluster NGC 6819 in the Kepler field, we present photometric (Kepler and ground-based BVR

C

I

C
) and spectroscopic observations of the detached eclipsing binary WOCS 24009 (Auner 665; KIC 5023948) with a short orbital period of 3.6 days. WOCS 24009 is a triple-lined system, and we verify that the brightest star is physically orbiting the eclipsing binary using radial velocities and eclipse timing variations. The eclipsing binary components have masses M

B
= 1.090 ± 0.010 M
⊙ and M

C
= 1.075 ± 0.013 M
⊙, and radii R

B
= 1.099 ± 0.006 ± 0.005 R
⊙ and R

C
= 1.069 ± 0.006 ± 0.013 R
⊙. The bright non-eclipsing star resides at the cluster turnoff, and ultimately its mass will directly constrain the turnoff mass: our preliminary determination is M

A
= 1.251 ± 0.057 M
⊙. A careful examination of the light curves indicates that the fainter star in the eclipsing binary undergoes a very brief period of total eclipse, which enables us to precisely decompose the light of the three stars and place them in the color–magnitude diagram (CMD). We also present improved analysis of two previously discussed detached eclipsing stars in NGC 6819 (WOCS 40007 and WOCS 23009) en route to a combined determination of the cluster’s distance modulus (m − M)
V
= 12.38 ± 0.04. Because this paper significantly increases the number of measured stars in the cluster, we can better constrain the age of the CMD to be 2.21 ± 0.10 ± 0.20 Gyr. Additionally, using all measured eclipsing binary star masses and radii, we constrain the age to 2.38 ± 0.05 ± 0.22 Gyr. The quoted uncertainties are estimates of measurement and systematic uncertainties (due to model physics differences and metal content), respectively.
A SOFT X-RAY SPECTRAL EPISODE FOR THE CLOCKED BURSTER, GS 1826–24 AS MEASURED BY SWIFT AND NuSTAR
Authors: Chenevez J. , Galloway D. K. , in ’t Zand J. J. M. , Tomsick J. A. , Barret D. , Chakrabarty D. , Fürst F. , Boggs S. E. , Christensen F. E. , Craig W. W. , Hailey C. J. , Harrison F. A. , Romano P. , Stern D. , Zhang W. W. 
Published: February 2016

ABSTRACT
We report on NuSTAR and Swift observations of a soft state of the neutron star low-mass X-ray binary GS 1826–24, commonly known as the “clocked” burster. The transition to the soft state was recorded in 2014 June through an increase of the 2–20 keV source intensity measured by MAXI, simultaneous with a decrease of the 15–50 keV intensity measured by Swift/BAT. The episode lasted approximately two months, after which the source returned to its usual hard state. We analyze the broadband spectrum measured by Swift/XRT and NuSTAR and estimate the accretion rate during the soft episode to be

, within the range of previous observations. However, the best-fit spectral model, adopting the double Comptonization used previously, exhibits significantly softer components. We detect seven type-I X-ray bursts, all significantly weaker (and with shorter rise and decay times) than observed previously. The burst profiles and recurrence times vary significantly, ruling out the regular bursts that are typical for this source. One burst exhibited photospheric radius expansion and we estimate the source distance as

kpc, where ξ

b
parameterizes the possible anisotropy of the burst emission. The observed soft state may most likely be interpreted as a change in accretion geometry at about similar bolometric luminosity as in the hard state. The different burst behavior can therefore be attributed to this change in accretion flow geometry, but the fundamental cause and process for this effect remain unclear.
Fe LINE DIAGNOSTICS OF CATACLYSMIC VARIABLES AND GALACTIC RIDGE X-RAY EMISSION
Authors: Xu Xiao-jie , Wang Q. Daniel , Li Xiang-Dong 
Published: February 2016

ABSTRACT
The properties of the Galactic Ridge X-ray Emission (GRXE) observed in the 2–10 keV band place fundamental constraints on various types of X-ray sources in the Milky Way. Although the primarily discrete origin of the emission is now well established, the responsible populations of these sources remain uncertain, especially at relatively low fluxes. To provide insights into this issue, we systematically characterize the Fe emission line properties of the candidate types of the sources in the solar neighborhood and compare them with those measured for the GRXE. Our source sample includes 6 symbiotic stars, 16 intermediate polars (IPs), 3 polars, 16 quiescent dwarf novae, and 4 active binaries (ABs); they are all observed with the Suzaku X-ray Observatory. The data of about one-fourth of these sources are analyzed for the first time. We find that the mean equivalent width (EW6.7) of the 6.7 keV line and the mean 7.0/6.7 keV line ratio are 107 ± 16.0 eV and 0.71 ± 0.04 for IPs and 221 ± 135 eV and 0.44 ± 0.14 for polars, respectively, which are all substantially different from those (490 ± 15 eV and 0.2 ± 0.08) for the GRXE. Instead, the GRXE values are better agreed by the EW6.7 (438 ± 84.6 eV) and the ratio (0.27 ± 0.06) observed for the DNe. We further find that the EW6.7 is strongly correlated with the 2–10 keV luminosity of the DNe, which can be characterized by the relation

. Accounting for this correlation, the agreement can be improved further, especially when the contributions from other class sources to the GRXE are considered, which all have low EW6.7 values. We conclude that the GRXE mostly consists of typically faint but numerous DNe, plus ABs, while magnetic cataclysmic variables are probably mainly the high-flux representatives of the responsible populations and dominate the GRXE only in harder energy bands.
SPECTROPOLARIMETRY CONFIRMS CENTRAL POWERING IN A Lyα NEBULA AT z = 3.09
Authors: Beck Melanie , Scarlata Claudia , Hayes Matthew , Dijkstra Mark , Jones Terry J. 
Published: February 2016

ABSTRACT
We present a follow-up study to the imaging polarimetry performed by Hayes et al. on LAB1 in the SSA22 protocluster region. Arguably the most well-known Lyα “blob,” this radio-quiet emission-line nebula likely hosts a galaxy that either is undergoing significant star formation or hosts an active galactic nucleus, or both. We obtain deep, spatially resolved spectropolarimetry of the Lyα emission and detect integrated linear polarization of 9%–13% ± 2%–3% at a distance of approximately 15 kpc north and south of the peak of the Lyα surface brightness with polarization vectors lying tangential to the galactic central source. In these same regions, we also detect a wavelength dependence in the polarization that is low at the center of the Lyα line profile and rises substantially in the wings of the profile. These polarization signatures are easily explained by a weak outflowing shell model. The spectral dependence of the polarization presented here provides a framework for future observations and interpretations of the southern portion of LAB1 in that any model for this system must be able to reproduce this particular spectral dependence. However, questions still remain for the northernmost spur of LAB1. In this region we detect total linear polarization of between 3% and 20% at the 5% significance level. Simulations predict that polarization should increase with radius for a symmetric geometry. That the northern spur does not suggests either that this region is not symmetric (which is likely) and exhibits variations in columns density or that it is kinematically distinct from the rest of LAB1 and powered by another mechanism altogether.
RECOVERY OF LARGE ANGULAR SCALE CMB POLARIZATION FOR INSTRUMENTS EMPLOYING VARIABLE-DELAY POLARIZATION MODULATORS
Authors: Miller N. J. , Chuss D. T. , Marriage T. A. , Wollack E. J. , Appel J. W. , Bennett C. L. , Eimer J. , Essinger-Hileman T. , Fixsen D. J. , Harrington K. , Moseley S. H. , Rostem K. , Switzer E. R. , Watts D. J. 
Published: February 2016

ABSTRACT
Variable-delay Polarization Modulators (VPMs) are currently being implemented in experiments designed to measure the polarization of the cosmic microwave background on large angular scales because of their capability for providing rapid, front-end polarization modulation and control over systematic errors. Despite the advantages provided by the VPM, it is important to identify and mitigate any time-varying effects that leak into the synchronously modulated component of the signal. In this paper, the effect of emission from a 300 K VPM on the system performance is considered and addressed. Though instrument design can greatly reduce the influence of modulated VPM emission, some residual modulated signal is expected. VPM emission is treated in the presence of rotational misalignments and temperature variation. Simulations of time-ordered data are used to evaluate the effect of these residual errors on the power spectrum. The analysis and modeling in this paper guides experimentalists on the critical aspects of observations using VPMs as front-end modulators. By implementing the characterizations and controls as described, front-end VPM modulation can be very powerful for mitigating 1/f noise in large angular scale polarimetric surveys. None of the systematic errors studied fundamentally limit the detection and characterization of B-modes on large scales for a tensor-to-scalar ratio of r = 0.01. Indeed, r < 0.01 is achievable with commensurately improved characterizations and controls.
MAGNETO-THERMAL DISK WINDS FROM PROTOPLANETARY DISKS
Authors: Bai Xue-Ning , Ye Jiani , Goodman Jeremy , Yuan Feng 
Published: February 2016

ABSTRACT
The global evolution and dispersal of protoplanetary disks (PPDs) are governed by disk angular-momentum transport and mass-loss processes. Recent numerical studies suggest that angular-momentum transport in the inner region of PPDs is largely driven by magnetized disk wind, yet the wind mass-loss rate remains unconstrained. On the other hand, disk mass loss has conventionally been attributed to photoevaporation, where external heating on the disk surface drives a thermal wind. We unify the two scenarios by developing a one-dimensional model of magnetized disk winds with a simple treatment of thermodynamics as a proxy for external heating. The wind properties largely depend on (1) the magnetic field strength at the wind base, characterized by the poloidal Alfvén speed v
Ap, (2) the sound speed c
s near the wind base, and (3) how rapidly poloidal field lines diverge (achieve

scaling). When

, corotation is enforced near the wind base, resulting in centrifugal acceleration. Otherwise, the wind is accelerated mainly by the pressure of the toroidal magnetic field. In both cases, the dominant role played by magnetic forces likely yields wind outflow rates that exceed purely hydrodynamical mechanisms. For typical PPD accretion-rate and wind-launching conditions, we expect v
Ap to be comparable to c
s at the wind base. The resulting wind is heavily loaded, with a total wind mass-loss rate likely reaching a considerable fraction of the wind-driven accretion rate. Implications for modeling global disk evolution and planet formation are also discussed.
CONSTRAINING THE RADIATION AND PLASMA ENVIRONMENT OF THE KEPLER CIRCUMBINARY HABITABLE-ZONE PLANETS
Authors: Zuluaga Jorge I. , Mason Paul A. , Cuartas-Restrepo Pablo A. 
Published: February 2016

ABSTRACT
The discovery of many planets using the Kepler telescope includes 10 planets orbiting eight binary stars. Three binaries, Kepler-16, Kepler-47, and Kepler-453, have at least one planet in the circumbinary habitable zone (BHZ). We constrain the level of high-energy radiation and the plasma environment in the BHZ of these systems. With this aim, BHZ limits in these Kepler binaries are calculated as a function of time, and the habitability lifetimes are estimated for hypothetical terrestrial planets and/or moons within the BHZ. With the time-dependent BHZ limits established, a self-consistent model is developed describing the evolution of stellar activity and radiation properties as proxies for stellar aggression toward planetary atmospheres. Modeling binary stellar rotation evolution, including the effect of tidal interaction between stars in binaries, is key to establishing the environment around these systems. We find that Kepler-16 and its binary analogs provide a plasma environment favorable for the survival of atmospheres of putative Mars-sized planets and exomoons. Tides have modified the rotation of the stars in Kepler-47, making its radiation environment less harsh in comparison to the solar system. This is a good example of the mechanism first proposed by Mason et al. Kepler-453 has an environment similar to that of the solar system with slightly better than Earth radiation conditions at the inner edge of the BHZ. These results can be reproduced and even reparameterized as stellar evolution and binary tidal models progress, using our online tool http://bhmcalc.net.
THE NANOGRAV NINE-YEAR DATA SET: MONITORING INTERSTELLAR SCATTERING DELAYS
Authors: Levin Lina , McLaughlin Maura A. , Jones Glenn , Cordes James M. , Stinebring Daniel R. , Chatterjee Shami , Dolch Timothy , Lam Michael T. , Lazio T. Joseph W. , Palliyaguru Nipuni , Arzoumanian Zaven , Crowter Kathryn , Demorest Paul B. , Ellis Justin A. , Ferdman Robert D. , Fonseca Emmanuel , Gonzalez Marjorie E. , Jones Megan L. , Nice David J. , Pennucci Timothy T. , Ransom Scott M. , Stairs Ingrid H. , Stovall Kevin , Swiggum Joseph K. , Zhu Weiwei 
Published: February 2016

ABSTRACT
We report on an effort to extract and monitor interstellar scintillation parameters in regular timing observations collected for the North American Nanohertz Observatory for Gravitational Waves pulsar timing array. Scattering delays are measured by creating dynamic spectra for each pulsar and observing epoch of wide-band observations centered near 1500 MHz and carried out at the Green Bank Telescope and the Arecibo Observatory. The ∼800 MHz wide frequency bands imply dramatic changes in scintillation bandwidth across the bandpass, and a stretching routine has been included to account for this scaling. For most of the 10 pulsars for which the scaling has been measured, the bandwidths scale with frequency less steeply than expected for a Kolmogorov medium. We find estimated scattering delay values that vary with time by up to an order of magnitude. The mean measured scattering delays are similar to previously published values and are slightly higher than predicted by interstellar medium models. We investigate the possibility of increasing the timing precision by mitigating timing errors introduced by the scattering delays. For most of the pulsars, the uncertainty in the time of arrival of a single timing point is much larger than the maximum variation of the scattering delay, suggesting that diffractive scintillation remains as only a negligible part of their noise budget.
HINTS OF A ROTATING SPIRAL STRUCTURE IN THE INNERMOST REGIONS AROUND IRC +10216
Authors: Quintana-Lacaci G. , Cernicharo J. , Agúndez M. , Prieto L. Velilla , Castro-Carrizo A. , Marcelino N. , Cabezas C. , Peña I. , Alonso J. L. , Zúñiga J. , Requena A. , Bastida A. , Kalugina Y. , Lique F. , Guélin M. 
Published: February 2016

ABSTRACT
The Atacama Large Millimeter/submillimeter Array is allowing us to study the innermost regions of the circumstellar envelopes of evolved stars with unprecedented precision and sensitivity. Key processes in the ejection of matter and dust from these objects occur in their inner zones. In this work, we present sub-arcsecond interferometric maps of transitions of metal-bearing molecules toward the prototypical C-rich evolved star IRC +10216. While Al-bearing molecules seem to be present as a roughly spherical shell, the molecular emission from the salts NaCl and KCl presents an elongation in the inner regions with a central minimum. In order to accurately analyze the emission from the NaCl rotational lines, we present new calculations of the collisional rates for this molecule based on new spectroscopic constants. The most plausible interpretation for the spatial distribution of the salts is a spiral with a NaCl mass of 0.08

. Alternatively, a torus of gas and dust would result in structures similar to those observed. From the torus scenario we derive a mass of ∼1.1 × 10−4

. In both cases, the spiral and the torus, the NaCl structure presents an inner minimum of 27 AU. In the case of the torus, the outer radius is 73 AU. The kinematics of both the spiral and the torus suggests that they are slowly expanding and rotating. Alternative explanations for the presence of the elongation are explored. The presence of these features only in KCl and NaCl might be a result of their comparatively high dipole moment with respect to the Al-bearing species.
A MASSIVE MOLECULAR GAS RESERVOIR IN THE z = 2.221 TYPE-2 QUASAR HOST GALAXY SMM J0939+8315 LENSED BY THE RADIO GALAXY 3C220.3
Authors: Leung T. K. Daisy , Riechers Dominik A. 
Published: February 2016

ABSTRACT
We report the detection of CO(J = 3

2) line emission in the strongly lensed submillimeter galaxy (SMG) SMM J0939+8315 at z = 2.221, using the Combined Array for Research in Millimeter-wave Astronomy. SMM J0939+8315 hosts a type-2 quasar, and is gravitationally lensed by the radio galaxy 3C220.3 and its companion galaxy at z = 0.685. The 104 GHz continuum emission underlying the CO line is detected toward 3C220.3 with an integrated flux density of S
cont = 7.4 ± 1.4 mJy. Using the CO(J = 3

2) line intensity of I
CO(3-2) = (12.6 ± 2.0) Jy km s−1, we derive a lensing- and excitation-corrected CO line luminosity of

= (3.4 ± 0.7) × 1010 (10.1/μ
L) K km s−1 pc2 for the SMG, where μ
L is the lensing magnification factor inferred from our lens modeling. This translates to a molecular gas mass of M
gas = (2.7 ± 0.6) × 1010 (10.1/μ
L) M
⊙. Fitting spectral energy distribution models to the (sub)-millimeter data of this SMG yields a dust temperature of T = 63.1

K, a dust mass of M
dust = (5.2 ± 2.1) × 108 (10.1/μ
L) M
⊙, and a total infrared luminosity of L
IR = (9.1 ± 1.2) ×1012 (10.1/μ
L) L
⊙. We find that the properties of the interstellar medium of SMM J0939+8315 overlap with both SMGs and type-2 quasars. Hence, SMM J0939+8315 may be transitioning from a starbursting phase to an unobscured quasar phase as described by the “evolutionary link” model, according to which this system may represent an intermediate stage in the evolution of present-day galaxies at an earlier epoch.
HIGH DYNAMIC RANGE OBSERVATIONS OF SOLAR CORONAL TRANSIENTS AT LOW RADIO FREQUENCIES WITH A SPECTRO-CORRELATOR
Authors: Hariharan K. , Ramesh R. , Kathiravan C. , Abhilash H. N. , Rajalingam M. 
Published: February 2016

ABSTRACT
A new antenna system with a digital spectro-correlator that provides high temporal, spectral, and amplitude resolutions has been commissioned at the Gauribidanur Observatory near Bangalore in India. Presently, it is used for observations of the solar coronal transients in the scarcely explored frequency range ≈30–15 MHz. The details of the antenna system, the associated receiver setup, and the initial observational results are reported. Some of the observed transients exhibited quasi-periodicity in their time profiles at discrete frequencies. Estimates of the associated magnetic field strength (B) indicate that B ≈ 0.06–1 G at a typical frequency such as 19.5 MHz.
ULTRA-LOW-TEMPERATURE REACTIONS OF CARBON ATOMS WITH HYDROGEN MOLECULES
Authors: Krasnokutski S. A. , Kuhn M. , Renzler M. , Jäger C. , Henning Th. , Scheier P. 
Published: February 2016

ABSTRACT
The reactions of carbon atoms with dihydrogen have been investigated in liquid helium droplets at T = 0.37 K. A calorimetric technique was applied to monitor the energy released in the reaction. The barrierless reaction between a single carbon atom and a single dihydrogen molecule was detected. Reactions between dihydrogen clusters and carbon atoms have been studied by high-resolution mass spectrometry. The formation of hydrocarbon cations of the type

with m = 1–4 and n = 1–15 was observed. With enhanced concentration of dihydrogen, the mass spectra demonstrated the main “magic” peak assigned to the

cation. A simple formation pathway and the high stability of this cation suggest its high abundance in the interstellar medium.
High Serum HCV RNA in Chronic Hepatitis C Patients Coinfected with HIV despite Successful Antiretroviral Therapy
Authors: Barreiro Pablo , Labarga Pablo , de Mendoza Carmen , Benítez-Gutiérrez Laura , Fernandez-Montero José V , Peña José M , Soriano Vicente 
Published: February 2016

Background Baseline serum HCV RNA predicts treatment success in chronic hepatitis C patients. Thresholds at 0.8, 2, 4 and 6 million IU/ml discriminate treatment outcomes using distinct antiviral regimens. Compared to the general population, immunosuppressed individuals exhibit greater viral load values. This has been confirmed in HIV– HCV-coinfected patients, although little is known about the influence of antiretroviral therapy. Methods Serum HCV RNA results recorded from all chronic hepatitis C patients who consecutively attended at our clinic were analysed. Results A total of 813 patients with detectable HCV RNA were identified. HIV coinfection was present in 78.7%, of whom 91% were on antiretroviral therapy. Overall, 467 (57%), 273 (34%), 170 (21%) and 127 (16%) had HCV RNA >0.8, >2, >4 and >6 million IU/ml, respectively. These high viral load values were found in 60%/36%/23%/18% of HIV-positive versus 47%/25%/11%/6% of HIV-negative individuals ( P≤0.01), respectively. In multivariate analysis, the greatest HCV RNA values were only significantly associated with HIV coinfection and HCV genotypes-1 or -4. Greater HCV RNA values were paradoxically found in HIV patients on than off antiretroviral therapy. Conclusions Serum HCV RNA values above 0.8, 2, 4 and 6 million IU/ml are roughly seen in 47%, 25%, 11% and 6% of chronic hepatitis C monoinfected patients, respectively. Despite being on antiretroviral therapy, the corresponding figures are 1.3- to 3.0-fold greater in HIV–HCV-coinfected patients, who may benefit less frequently from shorter oral HCV treatment lengths.
Vitamin D insufficiency among children with cancer in India
Authors: Mohan Ram , Mohan Gem , Scott Julius , Rajendran Aruna , Paramasivam Venkatraman , Ravindran Manipriya 
Published: February 2016

Abstract
Background: Vitamin D plays an important role in regulating various homeostatic mechanisms and has yet untapped potential in cancer prevention and prognosis. Only a few studies have been done worldwide in relating the Vitamin D levels in pediatric cancer patients to the general population but none so far in an Indian setting to the best of our knowledge. Objective: To compare the Vitamin D levels in a group of children with cancer to that of the general pediatric population and to note differences in the prevalence of Vitamin D insufficiency and make inferences arising from demographic and therapeutic variations. Materials and Methods: Vitamin D levels were found by immuno-chemilumino-metric assay in 102 children (51 cases and 51 controls) over a 6 months period. Results: In comparing the Vitamin D levels of children with cancer and controls from a healthy population we found an increased incidence of Vitamin D insufficiency in cancer children (80.39%) when compared to controls (50.98%) and a much lower mean Vitamin D value in cancer children (22.8 ng/ml) when compared to controls (33 ng/dl). It was also found that cancer children above 6 years had a greater chance for developing Vitamin D insufficiency (P = 0.038) as did children suffering from hematological malignancies (P = 0.025). Conclusion: Our study showed an increased prevalence of Vitamin D insufficiency in children with cancer and hence we suggest routine measurement of Vitamin D levels in children with cancer and subsequent supplementation.