One of the most mysterious astrophysical states is common envelope (CE) phase binary evolution, in which two stars are enshrouded by shed one them. Interactions between and shrinks orbit. The CE can lead to mergers or a subsequent interactions. Mergers may involve any combination compact objects and/or stars. Some involving white dwarfs, produce Type Ia supernovae, while merging neutron yield gamma-ray bursts, all kinds gravitational radiation. Since CEs arise from variety different initial...

We present a catalogue containing 839 candidate post common envelope systems. Common evolution is very important in stellar astrophysics, particularly the context of compact and short-period binaries, including cataclysmic variables, as progenitors e.g. supernovae type Ia or mergers black holes and/or neutron stars. At same time it barely understood process binary evolution. Due to limitations, since partially remedied, on direct simulation, early investigations were mainly focused providing...

An accurate short-term prediction of time series data is critical to operational decision-making. While most forecasts are made based on one selected model according certain criteria, there developments that harness the advantages different models by combining them together in process. Following from existing work, this paper applies six selection criteria and averaging (MA) a structural change vector Autoregressive model, compares terms both theoretical background empirical results. A case...

Since ARCH and GARCH models are presented, more authors interested in the study of volatilities financial markets with models. Method for estimating coefficients is mainly maximum likelihood estimation. Now we consider another method—MCMC method to substitute estimation method. Then compare three based on it. MCMC developed Markov chain, which one kind straggling time state random process no offspring imitates. It attracts extensive attention because its applications many fields. In this...

Type Ia supernovae luminosities can be corrected to render them useful as standard candles able probe the expansion history of universe. This technique was successful applied discover present acceleration As number SNe observed at high redshift increases and analysis techniques are perfected, people aim use this equation state dark energy. Nevertheless, nature progenitors remains controversial concerns persist about possible evolution effects that may larger harder characterize than more...

Barium stars have been studied extensively over the past few decades, yet our current understanding of how these intriguing objects formed leaves much to be desired. Many trends observed in systems containing barium cannot satisfactorily explained by classical binary evolution models, naturally raising question whether triples and other higher-order multiples can give rise such exotic objects. In this paper, we study possibility that a Roche Lobe overflow from tertiary hierarchical triple...

Studying the correlation of Type Ia supernova rates (SNRs) with host galaxy properties is an important step in understanding exact nature supernovae (SNe Ia). We use SNe from SDSS-II sample, spectroscopically determined masses and star formation rates, a new maximum likelihood method, to fit Scannapieco Bildsten rate model SNR = A × M + B SFR, where mass SFR rate. find 3.5+0.9−0.7 10−14 (SNe/yr)(M☉)−1 1.3+0.4−0.3 10−3 (SNe/yr)(M☉ yr−1)−1, assuming overall efficiency 0.5. This reasonable...

Stellar systems consisting of multiple stars tend to undergo tidal interactions when the separations between are short. While phenomena have been extensively studied, a certain effect exclusive hierarchical triples (triples in which one component star has much wider orbit than others) hardly received any attention, mainly due its complexity and consequent resistance being modelled. This is perturbation tertiary by inner binary, turn depletes orbital energy from causing binary separation...

Abstract We study how type Ia supernovae (SNe Ia) are spatially distributed within their host galaxies, using data taken from the Sloan Digital Sky Survey (SDSS). This paper specifically tests hypothesis that SNe rate traces r -band light of morphological component to which belong. A sample is SDSS SN Survey, and galaxies identified. Each galaxy decomposed into a bulge disk, distribution compared disk light. Our methodology relatively unaffected by seeing. find that, in dominated light,...

Existing theory and models suggest that a Type I (merger) GRB should have larger jet beaming angle than II (collapsar) GRB, but so far no statistical evidence is available to support this suggestion. In paper, we obtain sample of 37 angles calculate the probability true. A correction also devised account for scarcity GRBs in our sample. The calculated be 83% without 71% with it.

Abstract Important progress has been made with model averaging methods over the past decades. For spatial data, however, idea of not applied well. This article studies for geostatistical linear model. A Mallows criterion is developed to choose weights estimator. The resulting estimator can achieve asymptotic optimality in terms L 2 loss. Simulation experiments reveal that our proposed superior by ordinary models [Hansen, 2007] and selection using corrected Akaike's information criterion,...

Tertiary tides (TTs), or the continuous tidal distortion of tertiary in a hierarchical triple system, can extract energy from inner binary, inducing within it proclivity to merge. Despite previous work on subject, which established that is significant for certain close systems, still not well-understood process. A portion our ignorance this regard stems inability integrate simulation phenomenon into conventional stellar evolution codes, since full calculations these interactions are...

Recent studies on hypervelocity stars (HVSs) have generated a need to understand the high velocity limits of binary systems. If runaway systems with movement speeds well in excess 200km/s were exist, it would implications how HVS candidates are selected, and our current understanding they form needs be reinforced. In this paper, we explore possibility that such binaries (HVRBs) can engendered by supernova explosions tertiary close hierarchical triple We find lead significant remnant...

Several dozen hypervelocity star (HVS) candidates have been reported based on the second data release of Gaia (Gaia DR2). However, it has proven that radial velocities some HVS are not reliable. In this paper, we employ refined astrometric criteria to re-examine DR2, arriving at a more reliable sample and high velocity than those found by previous authors.We develop method called Binary Escape Probability Analysis identify candidates. This allows us work with stars having only two epochs...

Estimation of sinusoid frequency is a key research problem related to radar, sonar, and communication systems. The results numerous investigations on estimation have been reported in the literature. Nevertheless, best our knowledge, none them dealt with credibility evaluation, which used decide whether an individual estimate accurate or not. In this study, modeled as hypothesis test based Chebyshev’s inequality (CI). correlation calculated from received signal reference generated according...

ABSTRACT Many stars live in hierarchical triple systems, but the physics of such systems are still poorly understood. One understudied physical aspect these is tertiary tides, wherein tidal deformation a drains energy from inner binary, causing binary’s orbital separation to decrease. This process difficult observe directly, since an observation requires very compact triple, which must be almost large enough fill its Roche lobe at epoch observation. Concurrently, recently discovered stellar...

We study how type Ia supernovae (SNe Ia) are spatially distributed within their host galaxies, using data taken from the Sloan Digital Sky Survey (SDSS). This paper specifically tests hypothesis that SNe rate traces r-band light of morphological component to which belong. A sample is SDSS SN Survey, and galaxies identified. Each galaxy decomposed into a bulge disk, distribution compared disk light. Our methodology relatively unaffected by seeing. find in dominated trace closely. The...