Double Stars Research Articles

Long-term Evolution of a Supernova Remnant Hosting a Double Neutron Star Binary

An ultra-stripped supernova (USSN) is a type of core-collapse supernova explosion proposed to be a candidate formation site of a double neutron star (DNS) binary. We investigate the dynamical evolution of an ultra-stripped supernova remnant (USSNR), which should host a DNS at its center. By accounting for the mass-loss history of the progenitor binary using a model developed by a previous study, we construct the large-scale structure of the circumstellar medium (CSM) up to a radius ∼100 pc, and simulate the explosion and subsequent evolution of a USSN surrounded by such a CSM environment. We find that the CSM encompasses an extended region characterized by a hot plasma with a temperature ∼108 K located around the termination shock of the wind from the progenitor binary (∼10 pc), and the USSNR blast wave is drastically weakened while penetrating through this hot plasma. Radio continuum emission from a young USSNR is sufficiently bright to be detectable if it inhabits our galaxy but faint compared to the observed Galactic supernova remnants (SNRs), and thereafter declines in luminosity through adiabatic cooling. Within our parameter space, USSNRs typically exhibit a low radio luminosity and surface brightness compared to the known Galactic SNRs. Due to the small event rate of USSNe and their relatively short observable life span, we calculate that USSNRs account for only ∼0.1%–1% of the total SNR population. This is consistent with the fact that no SNR hosting a DNS binary has been discovered in the Milky Way so far.

Yet another star in the Albireo system

Context. Albireo is a well-known bright visual double star. It is still unclear if the components A and B form a gravitationally bound system. The component Albireo A is itself a binary star. The orbital parameters of the Albireo Aa, Ac system have been determined only recently. Thus, Albireo is still of interest for current research. Aims. We aim to present evidence for the detection of a new member in the Albireo system. Furthermore, we aim to determine the orbital parameters and to find further conclusions for the Albireo system. Methods. We used spectroscopic observations of Albireo A obtained with the TIGRE telescope and determined the radial velocities during a period of over three years. We analyzed the radial velocity curve with RadVel to determine the orbital parameters. In addition, we determined the stellar parameters of Albireo Aa with iSpec. Results. We found clear evidence for yet another star in the Albireo system orbiting Albireo Aa with a period of about P = 371 days. Several alternative explanations for the periodic radial velocity signal could be discarded. The new companion Albireo Ad is a low mass star of about 0.085 M⊙. Conclusions. We conclude that Albireo is a hierarchical multiple star system and remains an interesting object for future observations and studies.

Compact star merger events with stars composed of interacting strange quark matter

ABSTRACT We investigate the properties of stars participating in double compact star merger events considering interacting model of stable strange quark matter. We model the matter making it compatible with the recent astrophysical observations of compact star mass–radius and gravitational wave events. In this context, we consider modified MIT bag model and vector bag model with and without self-interaction. We find new upper bound on tidal deformability of $1.4\, {\rm M}_\odot$ strange star corresponding to the upper bound of effective tidal deformability inferred from gravitational wave event. Range of compactness of $1.4\, {\rm M}_\odot$ strange star is obtained as 0.175 ≤ C1.4 ≤ 0.199. Radius range of $1.5\, {\rm M}_\odot$ primary star is deduced to be 10.57 km ≤ R1.5 ≤ 12.04 km, following stringent GW170817 constraints. GW190425 constraints provide with upper limit on radius of 1.7 solar mass strange star that it should be less than $13.41\, \text{km}$.

Assignment-Control Plots: A Visual Companion for Causal Inference Study Design

An important step for any causal inference study design is understanding the distribution of the subjects in terms of measured baseline covariates. However, not all baseline variation is equally important. We propose a set of visualizations that reduce the space of measured covariates into two components of baseline variation important to the design of an observational causal inference study: a propensity score summarizing baseline variation associated with treatment assignment and a prognostic score summarizing baseline variation associated with the untreated potential outcome. These assignment-control plots and variations thereof visualize study design tradeoffs and illustrate core methodological concepts in causal inference. As a practical demonstration, we apply assignment-control plots to a hypothetical study of cardiothoracic surgery. To demonstrate how these plots can be used to illustrate nuanced concepts, we use them to visualize unmeasured confounding and to consider the relationship between propensity scores and instrumental variables. While the family of visualization tools for studies of causality is relatively sparse, simple visual tools can be an asset to education, application, and methods development.

Сommodity and Money Flows in Russian Empire in the Second half of the Nineteenth Century: Network and Geoinformation Analysis

This article deals with the domestic interregional cash flows in the Russian Empire, which flowed in the opposite direction to the flows of commodities and services; thus, they can be used as proxies of the resource allocation and uneven development of regions. This study is based on the statistics of transfers between branches of the State Bank of the Russian Empire, and it conducts a network and geoinformation analysis for 1868, 1878, 1888, and 1898. The study proves that the top segment of the payment network, including ties with St. Petersburg and Moscow, was organized like a “double star” (i.e., a star-type network with centers in two capitals with a huge flow between them). From St. Petersburg, the largest proportion of payments for goods and services were dispersed throughout the country, while Moscow was primarily a nationwide center for buying goods or receiving payments. The metropolitan segment always serviced more than half of all settlements in the country. In the European part of the empire, the largest regional ties (beyond the capitals) looked like the flows in the “pre-railway” period (1868); then, the largest flows were redistributed along the principal railways (1878); later, the flows compressed during the depression (1888); and then, the intraregional (local) flows increased sharply due to the expansion of local railroads (1898). Large interregional flows in the Asian part of the empire were inferior in size to those in the European part; until the 1890s, their main axis was the ties between Tomsk and Irkutsk as well as access to Nizhny Novgorod in the European part (through Yekaterinburg from the 1870s onwards). In the 1890s, new segments appeared in the Far East, in the Steppe Region (Kazakhstan), and in Central Asia.

Improved Monochromatic Double Stars in Edge Colorings

We give a slight improvement on the size of a monochromatic double star we can guarantee in every r-coloring of the edges of K_n.

Group inverses of matrices associated with certain graph classes

We obtain formulae for group inverses of matrices that are associated with a new class of digraphs obtained from stars. This new class contains both bipartite and non-bipartite graphs. Expressions for the group inverse of matrices corresponding to double star digraphs and the adjacency matrix of certain undirected multi-star graphs are also proven. A blockwise representation of the inverse or group inverse of the adjacency matrix of the Dutch windmill graph is presented.

The High Time Resolution Universe Pulsar Survey – XVII. PSR J1325−6253, a low eccentricity double neutron star system from an ultra-stripped supernova

ABSTRACT The observable population of double neutron star (DNS) systems in the Milky Way allow us to understand the nature of supernovae and binary stellar evolution. Until now, all DNS systems in wide orbits (Porb > 1 d) have been found to have orbital eccentricities, e > 0.1. In this paper, we report the discovery of pulsar PSR J1325−6253: a DNS system in a 1.81-d orbit with a surprisingly low eccentricity of just e = 0.064. Through, 1.4 yr of dedicated timing with the Parkes radio telescope we have been able to measure its rate of advance of periastron, $\dot{\omega }=0{_{.}^{\circ}}138\pm 0{_{.}^{\circ}}002\, \mathrm{yr}^{-1}$. If this induced $\dot{\omega }$ is solely due to general relativity then the total mass of the system is, Msys = 2.57 ± 0.06 M⊙. Assuming an edge-on orbit the minimum companion mass is constrained to be Mc, min > 0.98 M⊙ which implies the pulsar mass is Mp, max < 1.59 M⊙. Its location in the P–$\dot{P}$ diagram suggests that, like other DNS systems, PSR J1325−6253 is a recycled pulsar and if its mass is similar to the known examples (>1.3 M⊙), then the companion neutron star is probably less than ∼1.25 M⊙ and the system is inclined at about 50°–60°. The low eccentricity along with the wide orbit of the system strongly favours a formation scenario involving an ultra-stripped supernova explosion.

CHANG-ES – XXVII. A radio/X-ray catalogue of compact sources in and around edge-on galaxies

ABSTRACT We present catalogues of discrete, compact radio sources in and around the discs of 35 edge-on galaxies in the Continuum Halos in Nearby Galaxies – an EVLA Survey. The sources were extracted using the pybdsf program at both 1.6 GHz (L band) and 6.0 GHz (C band) from matching resolution (≈3 arcsec) data. We also present catalogues of X-ray sources from Chandra data sets for 27 of the galaxies. The sources at the two radio frequency bands were positionally cross-correlated with each other, and the result cross-correlated with the X-ray sources. All catalogues are included for download with this paper. We detect a total of 2507 sources at L band and 1413 sources at C band. 75 sources have been successfully cross-correlated in both radio bands plus X-ray. Three new nuclear sources are candidates for low luminosity active galactic nuclei in NGC 3877, NGC 4192, and NGC 5792; the one in NGC 3877 also appears to be variable. We also find new nuclear sources in two companion galaxies: NGC 4435 (companion to NGC 4438) and NGC 4298 (companion to NGC 4302). We have also discovered what appears to be a foreground double star; each star has X-ray emission and there is radio emission at both L band and C band in between them. This could be a colliding wind binary system. Suggestions for follow-up studies are offered.

Some results on generalized self-complementary graphs

Let [Formula: see text] be a partition of vertex set [Formula: see text] of order [Formula: see text] of a graph [Formula: see text]. The [Formula: see text]-complement of [Formula: see text] denoted by [Formula: see text] is defined as for all [Formula: see text] and [Formula: see text] in [Formula: see text], [Formula: see text], remove the edges between [Formula: see text] and [Formula: see text] in [Formula: see text] and add the edges between [Formula: see text] and [Formula: see text] which are not in [Formula: see text]. The graph [Formula: see text] is called [Formula: see text]-self-complementary if [Formula: see text]. For a graph [Formula: see text], [Formula: see text]-complement of [Formula: see text] denoted by [Formula: see text] is defined as for each [Formula: see text] remove the edges of [Formula: see text] inside [Formula: see text] and add the edges of [Formula: see text] by joining the vertices of [Formula: see text]. The graph [Formula: see text] is called [Formula: see text]-self-complementary if [Formula: see text] for some partition [Formula: see text] of order [Formula: see text]. In this paper, we determine generalized self-complementary graphs of forest, double star and unicyclic graphs.

Planet Hunters TESS IV: a massive, compact hierarchical triple star system TIC 470710327

ABSTRACTWe report the discovery and analysis of a massive, compact, hierarchical triple system (TIC 470710327) initially identified by citizen scientists in data obtained by NASA’s Transiting Exoplanet Survey Satellite (TESS). Spectroscopic follow-up observations obtained with the hermes spectrograph, combined with eclipse-timing variations (ETVs), confirm that the system is comprised of three OB stars, with a compact 1.10 d eclipsing binary and a non-eclipsing tertiary on a 52.04 d orbit. Dynamical modelling of the system (from radial velocity and ETVs) reveal a rare configuration wherein the tertiary star (O9.5-B0.5V; 14–17 M⊙) is more massive than the combined mass of the inner binary (10.9–13.2 M⊙). Given the high mass of the tertiary, we predict that this system will undergo multiple phases of mass transfer in the future, and likely end up as a double neutron star gravitational wave progenitor or an exotic Thorne–Żytkow object. Further observational characterization of this system promises constraints on both formation scenarios of massive stars as well as their exotic evolutionary end-products.

Orbital Elements of visual binary stars with very short arcs: With application to double stars from the 1829 southern double star catalog of James Dunlop

Binary double stars are those whose binding energies are less than zero. Obtaining binary star orbits from short arcs has been a long-standing problem in astrophysics. A method is presented and tested here, which addresses the problem by using space-based astrometry, photometry, and astrophysical data, together with historic measures, to generate and constrain a range of possible first-order Grade 5 orbits. After testing the method on an established binary star, we apply the method to eight double stars from the first published catalog of southern double stars, that of Dunlop (1829) and generate orbits for five. The mean orbital period is ∼81,000 years, and the mean semi-major axis is ∼76″ with a typical uncertainty of the Orbital Elements of ∼37%. Their Orbital Elements and associated plots are also presented.

A Single-lined Spectroscopic Binary Companion to an Active and Deep Contact Binary in a Quintuple Stellar System

Abstract V410 Aur is a known deep and low-mass-ratio contact binary with a spectroscopically tertiary component and a visual companion. However, the physical and orbital properties of the tertiary are unknown. We constructed (O − C) curve with 117 new eclipse times and those collected from the literature, which shows a cyclical variation with a period of 25.44 (±1.17) yr and a projected semimajor axis of 0.0348 (±0.0021) days while it undergoes a long-term period decrease at a rate of dP/dt = −1.58 × 10−7daysyr−1. The cyclical variation is analyzed for the light-travel time effect. The minimum mass of the third body is determined as 1.39 (±0.13) M ⊙ that is much larger than the inferred value (0.97 M ⊙) of spectroscopic investigation, which indicates that the spectroscopically tertiary is a single-lined spectroscopic binary with an unseen component. The maximum orbital semimajor axis 6.19 (±0.67) au of the third body is determined. Gaia detected a visual companion to V410 Aur at practically the same distance from the Sun nicely confirming the physical bond. These results reveal that V410 Aur contains a single-lined spectroscopic binary with a visual companion in a quintuple stellar system. TESS photometric solutions confirmed that V410 Aur is a deep overcontact binary with a fill-out factor of 73.83(88)% where the additional light contribution is about 24.80(18)%. The continuous variations of light curves are explained by the evolution of a dark spot on the more massive component. The parabolic variation in the (O − C) curve may be caused by the mass transfer from the massive component to the less massive one in the deep overcontact binary.

Reliable and Low-Power Communications System Based on IR-UWB for Offshore Wind Turbines

In this paper, we propose the design of a low-power wireless sensor network architecture that enables robust communications inside offshore wind turbines. This research work is in the scope of the WATEREYE EU Project, where we have designed a corrosion monitoring solution to work unattended. The architecture is composed of several fixed sensor nodes, one mobile sensor node, several anchors and the WATEREYE Computer (WEC). Our approach is based on Impulse Radio Ultra wideband (IR-UWB) technology offering reliable and low-power communications in these harsh environments. On top of that, we propose a double star network using two UWB channels for the following purposes: one network for communications to send the sensor data and another one for ranging estimations to calculate the indoor positioning of the mobile sensor node. The power strategies applied to our system, at Hardware (HW) and Firmware (FW) levels, are described in detail. Furthermore, we present power consumption measurements obtaining the power profiles and the autonomy of the most important components of the proposed architecture supplied by battery. On the other hand, we describe the methodology to analyze the range, reliability and continuity of the two UWB links providing the packet loss and gaps as a function of distance. The proposed communications system has been validated in three different scenarios considering two of them very hostile environments. Furthermore, one of the scenarios is a real offshore wind turbine.

Total neighborhood prime labeling of some trees

Let G be a graph with p vertices and q edges. A total neighborhood prime labeling of G is a labeling in which the vertices and edges are assigned labels from 1 to p + q such that the gcd of labeling in the neighborhood of each non degree 1 vertex is equal to 1 and the gcd of labeling in the edges of each non degree 1 vertex is equal to 1. A graph that admits a total neighborhood prime labeling is called a total neighborhood prime graph. In this paper, we examine total neighborhood prime labeling of trees such as (n, k, m) double star trees, spiders, caterpillars and firecrackers.

Stellar response after stripping as a model for common-envelope outcomes

ABSTRACT Binary neutron stars have been observed as millisecond pulsars, gravitational-wave sources, and as the progenitors of short gamma-ray bursts and kilonovae. Massive stellar binaries that evolve into merging double neutron stars are believed to experience a common-envelope episode. During this episode, the envelope of a giant star engulfs the whole binary. The energy transferred from the orbit to the envelope by drag forces or from other energy sources can eject the envelope from the binary system, leading to a stripped short-period binary. In this paper, we use one-dimensional single stellar evolution to explore the final stages of the common-envelope phase in progenitors of neutron star binaries. We consider an instantaneously stripped donor star as a proxy for the common-envelope phase and study the star’s subsequent radial evolution. We determine a range of stripping boundaries that allow the star to avoid significant rapid re-expansion and that thus represent plausible boundaries for the termination of the common-envelope episode. We find that these boundaries lie above the maximum compression point, a commonly used location of the core/envelope boundary. We conclude that stars may retain fractions of a solar mass of hydrogen-rich material even after the common-envelope episode. If we consider orbital energy as the only energy source available, all of our models would overfill their Roche lobe after ejecting the envelope, whose binding energy includes gravitational, thermal, radiation, and recombination energy terms.

The rainbow vertex antimagic coloring of tree graphs

Let G(V (G),E(G)) be a connected, simple, and finite graph. Let f be a bijective function of labeling on graph G from the edge set E(G) to natural number up to the number of edges of G. A rainbow vertex antimagic labeling of graph G is a function f under the condition all internal vertices of a path u – υ, Ɐu, υ ∈ V (G) have different weight (denoted by w(u)), where w(u) = ∑ uu′∈E(G)f (uu′). If G has a rainbow vertex antimagic labeling, then G is a rainbow vertex antimagic coloring, where the every vertex is assigned with the color w(u). The rvac(G) is a notation of rainbow vertex antimagic connection number of graph G which means the minimum colors taken over all rainbow vertex antimagic coloring induced by rainbow vertex antimagic labeling of graph G. The results of this research are the exact value of the rainbow vertex antimagic connection number of star (Sn ), double star (DSn ), and broom graph (Brn, m ).

The influence of initial orbital period on helium and carbon-oxygen core masses in massive case a binary systems with low accretion efficiency

The evolutionary models of 33 massive Case A binary systems in mass range from 30M? to 40M? with initial orbital periods of 3, 4 and 5 days, accretion efficiency of 10% and at the solar metallicity are presented. The models are obtained with the MESA (Modules for Experiments in Stellar Astrophysics) numerical code. The evolution is followed from a double O-type star, through Case A and Case mass transfer, to the formation of a carbon-oxygen (CO) core in the primary. The evolution of the secondary star in each binary system is further modeled with the same numerical code in an approximation of a single star, also to the formation of a carbon-oxygen core. The resulting helium core masses are in the range of 7.94M? - 13.19M? and 12.30M? and 19.12M? for primary and secondary stars, respectively. The carbon-oxygen core masses are between 5.26M? and 10M? for primaries and between 8.96M? and 15.32M? for secondaries. A clear influence of the initial orbital period on the resulting helium and CO core masses is demonstrated: primary stars in binary systems with initial orbital periods of 3, 4 and 5 days have on average about 15%, 8% and 2.5% smaller CO cores than single stars with the same initial masses. On the other hand, it was found that the correlation between the CO and helium core mass does not depend on the initial orbital period and can be approximated with the same linear fit for all binary systems. The CO/helium core mass ratio is found to be larger in binary systems than for single stars. It is also shown that the black hole formation limit for primary stars depends on the initial orbit and is between 33M? - 34M?, 32M? - 33M? and 30M? - 31M?, for the initial orbital periods of 3, 4 and 5 days, respectively. The resulting double compact objects are of two types: mixed neutron star - black hole systems (6 models) and double black holes (27 models). The resulting black hole masses are estimated to be in the range of 5M? to 17M?.

Magnetospheric Physics in China: 2020–2021

In the past two years, many progresses have been made in magnetospheric physics by using the data of Double Star Program, Cluster, THEMIS and RBSP missions, or by computer simulations. This paper briefly reviews these works based on papers selected from the 126 publications from March 2012 to March 2014. The subjects cover various sub-branches of magnetospheric physics,including geomagnetic storm, magnetospheric substorm and magnetic reconnection.

Massive Multi‐Mission Statistical Study and Analytical Modeling of the Earth's Magnetopause: 1. A Gradient Boosting Based Automatic Detection of Near‐Earth Regions

AbstractWe present an automatic classification method of the three near‐Earth regions, the magnetosphere, the magnetosheath and the solar wind from their in situ data measurement by multiple spacecraft. Based on gradient boosting classifier, this very simple and very fast method outperforms the detection routines based on manually set thresholds. The method is used to identify 15,062 magnetopause crossings and 17,227 bow shock crossings in the data of 11 different spacecraft of the THEMIS, ARTEMIS, Cluster, MMS, and Double Star missions and for a total of 83 cumulated years. These multi‐mission catalogs are easily reproducible, can be automatically enlarged with additional data and their elaboration paves the way for future massive statistical analysis of near‐Earth boundaries.