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At least 415 records · Page 23
All sourcesNASA NTRSDOE OSTI
NASA NTRS2019

Mutual Orbit Orientations of Transneptunian Binaries

We present Keplerian orbit solutions for the mutual orbits of 17 transneptunian binary systems (TNBs). For ten of them, the orbit had not previously been known: 60458 2000 CM (sub 114), 119979 2002 WC (sub 19), 160091 2000 OL (sub 67), 160256 2002 PD (sub 149), 469514 2003 QA (sub 91), 469705 ǂKagara, 508788 2000 CQ (sub 114), 508869 2002 VT (sub 130), 1999 RT (sub 214), and 2002 XH (sub 91). Seven more are systems where the size, shape, and period of the orbit had been published, but new observations have now eliminated the sky plane mirror ambiguity in its orientation: 90482 Orcus, 120347 Salacia-Actaea, 1998 WW (sub 31), 1999 OJ (sub 4), 2000 QL (sub 251), 2001 XR (sub 254), and 2003 TJ (sub 58). The dynamical masses we obtain from TNB mutual orbits can be combined with estimates of the objects' sizes from thermal observations or stellar occultations to estimate their bulk densities. The ǂKagara system is currently undergoing mutual events in which one component casts its shadow upon the other and/or obstructs the view of the other. Such events provide valuable opportunities for further characterization of the system. Combining our new orbits with previously published orbits yields a sample of 35 binary orbits with known orientations that can provide important clues about the environment in which outer solar system planetesimals formed, as well as their subsequent evolutionary history. Among the relatively tight binaries, with semimajor axes less than about 5 percent of their Hill radii, prograde mutual orbits vastly outnumber retrograde orbits. This imbalance is not attributable to any known observational bias. We suggest that this distribution could be the signature of planetesimal formation through gravitational collapse of local density enhancements such as caused by the streaming instability. Wider binaries, with semimajor axes greater than 5 percent of their Hill radii, are somewhat more evenly distributed between prograde and retrograde orbits, but with mutual orbits that are aligned or anti-aligned with their heliocentric orbits. This pattern could perhaps result from Kozai-Lidov cycles coupled with tidal evolution eliminating high inclination wide binaries.

Grundy, W. M.↗
NASA NTRS2021

Multiwavelength Observations of the RV Tauri Variable System U Monocerotis: Long-term Variability Phenomena That Can Be Explained by Binary Interactions with a Circumbinary Disk

We present an X-ray through submillimeter observations of the classical RV Tauri(RVb-type)variable U Mon, apost-asymptotic giant branch(AGB)binary with a circumbinary disk(CBD). Our SMA observations indicate aCBD diameter of550 au. Our XMM-Newton observations make U Mon thefirst RV Tauri variable detected inX-rays. The X-ray emission is characteristic of a hot plasma(∼10 MK), withLX=5×1030erg s−1, and weconsider its possible origin from U Mon, its companion, and/or binary system interactions. Combining DASCHand AAVSO data, we extend the time-series photometric baseline back to the late 1880s andfind evidence thatU Mon has secular changes that appear to recur on a timescale of∼60 yr, possibly caused by a feature in the CBD.From literature radial velocities wefind that the binary companion is a∼2MeA-type main-sequence star. Theorientation of the binary’s orbit lies along our line of sight(ω=95°), such that apastron corresponds to photometricRVb minima, consistent with the post-AGB star becoming obscured by the near side of the CBD. In addition, wefind the size of the inner-CBD hole(∼4.5–9au)to be comparable to the binary separation, implying that one orboth stars may interact with the CBD at apastron. The obscuration of the post-AGB star implicates the companionas the likely source of the enhanced Hαobserved at RVb minima and of the X-ray emission that may arise fromaccreted material.

Laura D Vega↗
NASA NTRS2020

Properties and Astrophysical Implications of the 150 M Binary Black Hole Merger GW190521

The gravitational-wave signal GW190521 is consistent with a binary black hole (BBH) merger source at redshift 0.8 with unusually high component masses, 85 (+21,-14) Mꙩ and 66 (+17,-18) Mꙩ, compared to previously reported events, and shows mild evidence for spin-induced orbital precession. The primary falls in the mass gap predicted by (pulsational) pair-instability supernova theory, in the approximate range 65–120 Mꙩ. The probability that at least one of the black holes in GW190521 is in that range is 99.0%. The final mass of the merger (142 (+28,-16) Mꙩ) classifies it as an intermediate-mass black hole. Under the assumption of a quasi-circular BBH coalescence, we detail the physical properties of GW190521’s source binary and its post-merger remnant, including component masses and spin vectors. Three different waveform models, as well as direct comparison to numerical solutions of general relativity, yield consistent estimates of these properties. Tests of strong-field general relativity targeting the merger-ringdown stages of the coalescence indicate consistency of the observed signal with theoretical predictions. We estimate the merger rate of similar systems to be 0.13 (+0.30,-0.11)Gp/cu.c yr. We discuss the astrophysical implications of GW190521 for stellar collapse and for the possible formation of black holes in the pair-instability mass gap through various channels: via (multiple) stellar coalescences, or via hierarchical mergers of lower-mass black holes in star clusters or in active galactic nuclei. We find it to be unlikely that GW190521 is a strongly lensed signal of a lower-mass black hole binary merger. We also discuss more exotic possible sources for GW190521, including a highly eccentric black hole binary, or a primordial black hole binary.

R. Abbott↗
NASA NTRS2022

X-Ray Imaging Observations of the High-Mass γ-Ray Binary HESS J0632+057

The Chandra X-ray Observatory (CXO)imaged the high-massγ-ray binary (HMGB) HESS8J0632+057 with the Advanced CCD Imaging Spectrometer (ACIS). We analyzed the CXO data to-9gether with 967 ks of archival imaging Swift-XRT observations. On arcsecond scales we find a hint10of asymmetric extended emission. On arcminute scales, there is a region of extended emission (“the11blob”) which is located≈5.5′east of the binary. The blob is seen in both the CXO-ACIS and the12Swift-XRT images but it does not have a counterpart in the radio, NIR, IR, or optical images. The13ACIS spectrum of the blob fits either an absorbed power-law model with Γ'2.6, or a thermal plasma14model withkT'3 keV. Since the blob’s NH is significantly larger than that of the binary we conclude15that the blob and binary are not directly related. The somewhat larger very deep XRT image suggests16that the binary may be located within a shell (or cavity). The four ACIS spectra taken within the∼2017day interval near the light curve minimum suggests that the NH is varying on timescales of days, pos-18sibly due to the inhomogenous circumbinary environment. The XRT spectra extracted from the wider19orbital phase intervals support significant changes in NH near the light curve maximum/minimum,20which may be responsible for the substantial systematic residuals seen near 1 keV, and provide tenta-21tive evidence for a Fe line at 6.4 keV. We find no significant periodic signal in the ACIS data up to 0.156 Hz.

O Kargaltsev↗
DOE OSTI2014

Binary classification of items of interest in a repeatable process

A system includes host and learning machines in electrical communication with sensors positioned with respect to an item of interest, e.g., a weld, and memory. The host executes instructions from memory to predict a binary quality status of the item. The learning machine receives signals from the sensor(s), identifies candidate features, and extracts features from the candidates that are more predictive of the binary quality status relative to other candidate features. The learning machine maps the extracted features to a dimensional space that includes most of the items from a passing binary class and excludes all or most of the items from a failing binary class. The host also compares the received signals for a subsequent item of interest to the dimensional space to thereby predict, in real time, the binary quality status of the subsequent item of interest.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2015

Binary classification of items of interest in a repeatable process

A system includes host and learning machines. Each machine has a processor in electrical communication with at least one sensor. Instructions for predicting a binary quality status of an item of interest during a repeatable process are recorded in memory. The binary quality status includes passing and failing binary classes. The learning machine receives signals from the at least one sensor and identifies candidate features. Features are extracted from the candidate features, each more predictive of the binary quality status. The extracted features are mapped to a dimensional space having a number of dimensions proportional to the number of extracted features. The dimensional space includes most of the passing class and excludes at least 90 percent of the failing class. Received signals are compared to the boundaries of the recorded dimensional space to predict, in real time, the binary quality status of a subsequent item of interest.

97 MATHEMATICS AND COMPUTING↗
NASA NTRS2015

A Coordinated X-Ray and Optical Campaign of the Nearby Massive Binary Sigma Orionis Aa: X-Ray Variability - II

We present time-resolved and phase-resolved variability studies of an extensive X-ray high-resolution gratings spectral dataset of the Sigma Ori Aa binary system. The four observations, obtained with Chandra ACIS HETGS, have a total exposure time of approximately 479 kiloseconds and provide nearly complete binary phase coverage. Variability of the total X-ray flux in the range 5-25 angstroms is confirmed, with maximum amplitude of about plus or minus 15 percent within a single approximately 125 kiloseconds observation. Periods of 4.76 days and 2.04 days are found in the total X-ray flux, as well as an apparent overall increase in flux level throughout the 9-day observational campaign. Using 40 kiloseconds contiguous spectra derived from the original observations, we investigate variability of emission line parameters and ratios. Several emission lines are shown to be variable, including S XV, Si XIII, and Ne IX. For the first time, variations of the X-ray emission line widths as a function of the binary phase are found in a binary system, with the smallest widths at phi equals 0.0 when the secondary Aa2 is at inferior conjunction. We use the results of an SPH radiative transfer code model, customized for this project, to relate the presence of a low density cavity in the primary stellar wind embedded shock that is associated with the secondary star to the emission line width variability.

binaries: closeaEuro"binaries: eclipsingaEuro"star↗
DOE OSTI2018

Effect of alloying elements on defect evolution in Ni-20X binary alloys

The effect of alloying elements on radiation-induced microstructural evolution in Ni and Ni-20X (X = Fe, Cr, Mn and Pd) binary alloys was investigated using ion irradiation and cross-sectional transmission electron microscopy. The three-dimensional migration mode is identified to be the dominating migration mechanism for interstitial clusters in these binary alloys, contrary to the one-dimensional mode that dominates in the well-studied dilute alloys. The results reveal that: (1) the average size of defect clusters decreases as the solute atomic volume size factor increases. Smaller void size in Ni-20Cr is attributed to faster vacancy mobility in the near surface region, and weaker vacancy binding energy beyond the irradiation peak than Ni-20Fe. The smaller voids observed in Ni-20Mn and Ni-20Pd beyond the damage peak are due to the stronger Mn/Pd-vacancy binding effect of largely oversized solute atoms. (2) Oversized solutes can act as strong trapping sites for interstitials. The larger the solute atomic volume factor, the stronger the trapping force. This leads to a more significantly sluggish interstitial migration and smaller dislocation loop size. The average dislocation loop size in Ni-20Fe was four times larger than Ni-20Pd (atomic volume factor being 10.6% and 41.3%) but an order of magnitude lower in density. The smaller dislocation loop size in Ni-20Cr is attributed to stronger interstitial binding of Cr-Ni. In conclusion, overall, the alloying effect on defects is more significant in concentrated binary alloys than in dilute binary alloys, due to the concentration difference of alloying atoms and the interstitial dominant migration mechanisms in the main irradiated region.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Multi-messenger EOS constraints using binary NS mergers

Though nearly five decades in the making, the opening mark of gravitational wave (GW) astronomy has only just now sounded. This novel field holds great scientific promise in the upcoming years, and yet already with a single binary NS merger event — it has managed to deliver results beyond our hopes and expectations. A primary factor in this success is the fact that this first binary NS merger, GW170817, was successfully followed up and detected in wavelengths spanning the observable electromagnetic (EM) spectrum. This ‘multi-messenger’ view of binary NS mergers opens new windows of opportunity for maximizing the scientific return from these events, and has facilitated constraints on physics ranging from cosmology, to general relativity, and nuclear physics. In the following I review constraints on the equation of state (EOS) of dense nuclear matter which can be obtained from multi-messenger analyses of binary NS mergers, showing that these are complementary to alternative approaches of constraining the EOS using GW data alone, and summarizing the main results arising from GW170817.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2023

Thermodynamic analysis of a two-stage binary-fluid ejector heat pump water heater

Ejector heat pump water heaters (EHPWHs) could significantly increase the thermal efficiency of domestic water heating and reduce greenhouse gas emissions. This study addresses two major technical barriers to using EHPWHs in domestic water heating—low heating cycle coefficient of performance (COP) and low condensation temperatures—using binary fluid pairs as a working fluid in a two-stage ejector system. A comprehensive, geometry-free model of binary-fluid ejectors was built and validated to predict the entrainment ratios of binary-fluid ejectors. A thermodynamic model of a two-stage binary-fluid ejector EHPWH was built to predict the heating cycle COP of EHPWHs. The performance of the EHPWH was theoretically evaluated using HFE7000 and Novec649 as primary fluids and R600 and R1234ze(Z) as secondary fluids. HFE7000/R600 gave the highest heating cycle COP (i.e., 1.356) in producing domestic hot water at 60.0 °C. An optimum evaporation temperature of the primary fluid was identified for the maximum effective entrainment ratio and effective pressure lift ratio of two-stage ejectors. Here, the effective entrainment ratio of the two-stage ejector dominated the heating cycle COP of the EHPWH. Primary fluids with lower latent heats of evaporation and/or secondary fluids with higher latent heats of evaporation yielded higher heating cycle COPs of EHPWHs.

42 ENGINEERING↗
DOE OSTI2015

Ab initio atomistic thermodynamics study on the oxidation mechanism of binary and ternary alloy surfaces

Utilizing a combination of ab initio density-functional theory and thermodynamics formalism, we have established the microscopic mechanisms for oxidation of the binary and ternary alloy surfaces and provided a clear explanation for the experimental results of the oxidation. We construct three-dimensional surface phase diagrams (SPDs) for oxygen adsorption on three different Nb-X(110) (X = Ti, Al or Si) binary alloy surfaces. On the basis of the obtained SPDs, we conclude a general microscopic mechanism for the thermodynamic oxidation, that is, under O-rich conditions, a uniform single-phase SPD (type I) and a nonuniform double-phase SPD (type II) correspond to the sustained complete selective oxidation and the non-sustained partial selective oxidation by adding the X element, respectively. Furthermore, by revealing the framework of thermodynamics for the oxidation mechanism of ternary alloys through the comparison of the surface energies of two separated binary alloys, we provide an understanding for the selective oxidation behavior of the Nb ternary alloy surfaces. Using these general microscopic mechanisms, one could predict the oxidation behavior of any binary and multi-component alloy surfaces based on thermodynamics considerations.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Final binary star results from the ESO VLT Lunar occultations program

We report on 13 subarcsecond binaries, detected by means of lunar occultations in the near-infrared at the ESO Very Large Telescope (VLT). They are all first-time detections except for the visual binary HD 158122, which we resolved for the first time in the near-infrared. The primaries have magnitudes in the range K = 4.5-10.0, and companions in the range K = 6.8-11.1. The magnitude differences have a median value of 2.4, with the largest being 4.6. The projected separations are in the range of 4-168 mas, with a median of 13 mas. We discuss and compare our results with the available literature. With this paper, we conclude the mining for binary star detections in the 1226 occultations recorded at the VLT with the ISAAC instrument. We expect that the majority of these binaries may be unresolvable by adaptive optics on current telescopes, and they might be challenging for long-baseline interferometry. However, they constitute an interesting sample for future larger telescopes and for astrometric missions such as GAIA.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2014

From binaries to multiples. II. Hierarchical multiplicity of F and G dwarfs

Statistics of hierarchical multiplicity among solar-type dwarfs are studied using the distance-limited sample of 4847 targets presented in the accompanying Paper I. Known facts about binaries (multiplicity fraction 0.46, lognormal period distribution with median period 100 yr and logarithmic dispersion 2.4, and nearly uniform mass-ratio distribution independent of the period) are confirmed with a high statistical significance. The fraction of hierarchies with three or more components is 0.13 ± 0.01, and the fractions of targets with n = 1, 2, 3, ... components are 54:33:8:4:1. Subsystems in the secondary components are almost as frequent as in the primary components, but in half of such cases both inner pairs are present. The high frequency of those 2+2 hierarchies (4%) suggests that both inner pairs were formed by a common process. The statistics of hierarchies can be reproduced by simulations, assuming that the field is a mixture coming from binary-rich and binary-poor environments. Periods of the outer and inner binaries are selected recursively from the same lognormal distribution, subject to the stability constraint and accounting for the correlation between inner subsystems. The simulator can be used to evaluate the frequency of multiple systems with specified parameters. However, it does not reproduce the observed excess of inner periods shorter than 10 days, caused by tidal evolution.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2014

Photometric properties for selected algol-type binaries. VIII. The triple systems DI Peg and AF Gem revisited

New extensive photometry for two triple binary stars, DI Peg and AF Gem, was performed from 2012 October to 2013 January, with two small telescopes at Xinglong station (XLs) of NAOC. From new multi-color observations and previously published ones in literature, the photometric models were (re)deduced using the updated Wilson-Devinney code. The results indicated that the low third lights exist in two classic Algol-type binaries, whose fill-out factors for the more massive components are f{sub p} = 78.2(± 0.4)% for DI Peg, and f{sub p} = 69.0(± 0.3)% for AF Gem, respectively. Through analyzing the O–C curves, the orbital periods for two binaries change in the complicated mode. The period of DI Peg possibly appears to show two light-time orbits, whose modulated periods are P {sub 3} = 54.6(± 0.5) yr and P {sub 4} = 23.0(± 0.6) yr, respectively. The inferred minimum masses for the inner and outer sub-stellar companions are M {sub in} = 0.095 M {sub ☉} and M {sub out} = 0.170 M {sub ☉}, respectively. Therefore, DI Peg may be a quadruple star. The orbital period of AF Gem appears to show a continuous period decrease or a cyclic variation; the latter may be preferable. The cyclic oscillation, with a period of 120.3(± 2.5) yr, may be attributed to the light-time effect due to the third body. This kind of additional companion may extract angular momentum from the central system, which may play a key role in the evolution of the binary.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2014

The EB factory project. I. A fast, neural-net-based, general purpose light curve classifier optimized for eclipsing binaries

We describe a new neural-net-based light curve classifier and provide it with documentation as a ready-to-use tool for the community. While optimized for identification and classification of eclipsing binary stars, the classifier is general purpose, and has been developed for speed in the context of upcoming massive surveys such as the Large Synoptic Survey Telescope. A challenge for classifiers in the context of neural-net training and massive data sets is to minimize the number of parameters required to describe each light curve. We show that a simple and fast geometric representation that encodes the overall light curve shape, together with a chi-square parameter to capture higher-order morphology information results in efficient yet robust light curve classification, especially for eclipsing binaries. Testing the classifier on the ASAS light curve database, we achieve a retrieval rate of 98% and a false-positive rate of 2% for eclipsing binaries. We achieve similarly high retrieval rates for most other periodic variable-star classes, including RR Lyrae, Mira, and delta Scuti. However, the classifier currently has difficulty discriminating between different sub-classes of eclipsing binaries, and suffers a relatively low (∼60%) retrieval rate for multi-mode delta Cepheid stars. We find that it is imperative to train the classifier's neural network with exemplars that include the full range of light curve quality to which the classifier will be expected to perform; the classifier performs well on noisy light curves only when trained with noisy exemplars. The classifier source code, ancillary programs, a trained neural net, and a guide for use, are provided.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2014

AL Cassiopeiae: An F-type contact binary system with a cool stellar companion

According to the general catalog of variable stars, AL Cas was classified as an EW-type eclipsing binary with a spectral type of B and an orbital period of P = 0.5005555 days. The first photometric light curves of the close binary in the B, V, R, and I bands are presented. New low-resolution spectra indicate that its spectral type is about F7 rather than B-type. A photometric analysis with the Wilson-Devinney method suggests that it is a contact binary (f = 39.3%) with a mass ratio of 0.61. Using 17 newly determined eclipse times together with those collected from the literature, we found that the observed–calculated (O – C) curve of AL Cas shows a cyclic change with a period of 86.6 yr and an amplitude of 0.0181 days. The periodic variation was analyzed for the light-travel time effect via the presence of a third body. The mass of the third body was determined to be M {sub 3}sin i' = 0.29(± 0.05) M {sub ☉} when a total mass of 2.14 M {sub ☉} for AL Cas is adopted. It is expected that the cool companion star may have played an important role in the origin and evolution of the system by removing angular momentum from the central binary system during early dynamical interaction and/or late dynamical evolution. This causes the original detached system to have a low angular momentum and a short initial orbital period. Then it can evolve into the present contact configuration via a case A mass transfer.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2015

A new merging double degenerate binary in the solar neighborhood

Characterizing the local space density of double degenerate (DD) binary systems is a complementary approach to broad sky surveys of DDs to determine the expected rates of WD binary mergers, in particular those that may evolve into other observable phenomena such as extreme helium stars, Am CVn systems, and SNe Ia. However, there have been few such systems detected in local space. We report here the discovery that WD 1242–105, a nearby bright WD, is a double-line spectroscopic binary consisting of two degenerate DA WDs of similar mass and temperature, despite it previously having been spectroscopically characterized as a single degenerate. Follow-up photometry, spectroscopy, and trigonometric parallax have been obtained in an effort to determine the fundamental parameters of each component of this system. The binary has a mass ratio of 0.7 and a trigonometric parallax of 25.5 mas, placing it at a distance of 39 pc. The system’s total mass is 0.95 M{sub ⊙} and has an orbital period of 2.85 hr, making it the strongest known gravitational wave source (logh=−20.78) in the mHz regime. Because of its orbital period and total mass, WD 1242–105 is predicted to merge via gravitational radiation on a timescale of 740 Myr, which will most likely not result in a catastrophic explosion.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2014

Calibrating the updated overshoot mixing model on eclipsing binary stars: HY Vir, YZ Cas, χ{sup 2} Hya, and VV Crv

Detached eclipsing binary stars with convective cores provide a good tool to investigate convective core overshoot. It has been performed on some binary stars to restrict the classical overshoot model which simply extends the boundary of the fully mixed region. However, the classical overshoot model is physically unreasonable and inconsistent with helioseismic investigations. An updated model of overshoot mixing was established recently. There is a key parameter in the model. In this paper, we use observations of four eclipsing binary stars, i.e., HY Vir, YZ Cas, χ{sup 2} Hya, and VV Crv, to investigate a suitable value for the parameter. It is found that the value suggested by calibrations on eclipsing binary stars is the same as the value recommended by other methods. In addition, we have studied the effects of the updated overshoot model on the stellar structure. The diffusion coefficient of convective/overshoot mixing is very high in the convection zone, then quickly decreases near the convective boundary, and exponentially decreases in the overshoot region. The low value of the diffusion coefficient in the overshoot region leads to weak mixing and a partially mixed overshoot region. Semi-convection, which appears in the standard stellar models of low-mass stars with convective cores, is removed by partial overshoot mixing.

79 ASTRONOMY AND ASTROPHYSICS↗