Binary Star Systems Research Articles

On the Earth’s Electric Field Components Spectrally Localized at the Gravitational Waves of the Relativistic Binary Star Systems

On the Earth’s Electric Field Components Spectrally Localized at the Gravitational Waves of the Relativistic Binary Star Systems

The Missing Link: Testing Galactic Chemical Evolution Models with the First Multi-isotopic Abundances in Solar Twin Stars

We present the first isotopic abundances of both 13CO and C18O in solar twin stars and test the results against several galactic chemical evolution (GCE) models with different nucleosynthesis prescriptions. First, we compare M-band spectra from IRTF/iSHELL to synthetic spectra generated from custom solar atmosphere models using the PHOENIX atmosphere code. Next, we compare our calculated abundances to GCE models that consider isotopic yields from massive stars, asymptotic giant branch stars, and fast-rotating stars. The 12C/13C ratios determined for this sample of solar twins are consistent with predictions from the selected GCE models; however, the 16O/18O ratios tentatively contradict these predictions. This project constitutes the first in a stellar chemical abundance series seeking to (1) support the James Webb Space Telescope as it characterizes exoplanet atmospheres, interiors, and biosignatures by providing host star abundances; (2) identify how unexplored stellar abundances reveal the process of galactic chemical evolution and correlate with star formation, interior, age, metallicity, and activity; and (3) provide improved stellar ages using stellar abundance measurements. By measuring elemental and isotopic abundances in a variety of stars, we not only supply refined host star parameters, but also provide the necessary foundations for complementary exoplanet characterization studies—and ultimately contribute to the exploration of galactic, stellar, and planetary origins and evolution.

Analytic Understanding of the Resonant Nature of Kozai–Lidov Cycles with a Precessing Quadrupole Potential

The very long-term evolution of the hierarchical restricted three-body problem with a slightly aligned precessing quadrupole potential is studied analytically. This problem describes the evolution of a star and a planet that are perturbed either by a (circular and not too inclined) binary star system or by one other star and a second more distant star, as well as a perturbation by one distant star and the host galaxy or a compact-object binary system orbiting a massive black hole in nonspherical nuclear star clusters. Previous numerical experiments have shown that when the precession frequency is comparable to the Kozai–Lidov timescale, long-term evolution emerges that involves extremely high eccentricities with potential applications for a broad scope of astrophysical phenomena, including systems with merging black holes, neutron stars, or white dwarfs. By averaging the secular equations of motion over the Kozai–Lidov cycles (KLCs), we solve the problem analytically in the neighborhood of the KLC fixed point where the eccentricity vector is close to unity and aligned with the quadrupole axis and for a precession rate similar to the Kozai–Lidov timescale. In this regime the dynamics is dominated by a resonance between the perturbation frequency and the precession frequency of the eccentricity vector. While the quantitative evolution of the system is not reproduced by the solution far away from this fixed point, it sheds light on the qualitative behavior.

Complete analysis of the subgiant stellar system: HIP 102029

In this work, we present a detailed analysis of the individual components of the visual binary system HIP 102029 (R.A. = 20:40:35.32, Dec. = +15:38:35.63). The system was discovered during the European Space Agency Hipparcos mission and has a separation of 220 mas. The analysis uses the ORBITX code and Al-Wardat’s method to estimate the orbital, atmospheric, and fundamental parameters of the individual components. The positions of the components on the H-R diagram, evolutionary tracks, and isochrones are determined using the estimated parameters. The age of the system is estimated to be 1.415 Gyr with a higher metallicity than the Sun Z=0.030 based on the Gaia BP/RP spectrum. The results show that component A has evolved from the main sequence to the sub-giant stage, while component B has started to evolve off the main sequence. This study provides valuable insights into the properties and evolution of binary star systems, which can contribute to our broader understanding of stellar evolution in the subgiant stage.

Discovery and characterization of two Neptune-mass planets orbiting HD 212729 with TESS

ABSTRACT We report the discovery of two exoplanets orbiting around HD 212729 (TOI 1052, TIC 317060587), a Teff = 6146 K star with V = 9.51 observed by TESS in Sectors 1 and 13. One exoplanet, TOI-1052b, is Neptune-mass and transits the star, and an additional planet TOI-1052c is observed in radial velocities but not seen to transit. We confirm the planetary nature of TOI-1052b using precise radial velocity observations from HARPS and determined its parameters in a joint RV and photometry analysis. TOI-1052b has a radius of $2.87^{+0.29}_{-0.24}$ R⊕, a mass of 16.9 ± 1.7 M⊕, and an orbital period of 9.14 d. TOI-1052c does not show any transits in the TESS data, and has a minimum mass of $34.3^{+4.1}_{-3.7}$ M⊕ and an orbital period of 35.8 d, placing it just interior to the 4:1 mean-motion resonance. Both planets are best fit by relatively high but only marginally significant eccentricities of $0.18^{+0.09}_{-0.07}$ for planet b and $0.24^{+0.09}_{-0.08}$ for planet c. We perform a dynamical analysis and internal structure model of the planets as well as deriving stellar parameters and chemical abundances. The mean density of TOI-1052b is $3.9^{+1.7}_{-1.3}$ g cm−3 consistent with an internal structure similar to Neptune. A nearby star is observed in Gaia DR3 with the same distance and proper motion as TOI-1052, at a sky projected separation of $\scriptstyle \sim$1500 au, making this a potential wide binary star system.

Everything that glitters is not gold: V1315 Cas is not a dormant black hole

ABSTRACT The quest for quiet or dormant black holes has been ongoing since several decades. Ellipsoidal variables possibly indicate the existence of a very high-mass invisible companion and are thought to be one of the best ways to find such dormant black holes. This, however, is not a panacea as we show here with one example. We indeed report the discovery of a new semidetached interacting binary, V1315 Cas, discovered as an ellipsoidal variable. Using data from photometric surveys (ASAS-SN, TESS) and high-resolution spectroscopy, we derived a nearly circular orbit with an orbital period of Porb = 34.54 d. The binary system consists of an evolved F-type star primary that is likely still filling its Roche lobe and a B-type star secondary. Using phoebe2, we derived the following masses and radii: for the primary, $M_p =0.84 \pm 0.03 \, \rm {M}_{\odot}$ and $R_p =18.51^{+0.12}_{-0.07} \, \rm {R}_{\odot}$; for the secondary, $M_s =7.3 \pm 0.3 \, \rm {M}_{\odot}$ and $R_s =4.02^{+2.3}_{-2.0}\, \rm {R}_{\odot}$. Modelling the evolution of the system with mesa, we found an age of ∼7.7 × 107 yr. The system is at the end of a period of rapid non-conservative mass transfer that reversed its mass ratio, while significantly widening its orbit. The primary shows carbon depletion and nitrogen overabundance, indicative of CNO-processed material being exposed due to mass transfer. An infrared excess and stationary H α emission suggest the presence of a circumstellar or circumbinary disc. V1315 Cas will likely become a detached stripped star binary.

Using grey sirens to resolve the Hubble–Lemaître tension

ABSTRACT The measurement of the Hubble–Lemaître constant (H0) from the cosmic microwave background and the Type IA supernovae are at odds with each other. One way to resolve this tension is to use an independent way to measure H0. This can be accomplished by using gravitational-wave (GW) observations. Previous works have shown that with the onset of the next generation of GW detector networks, it will be possible to constrain H0 to better than 2 per cent precision (which is enough to resolve the tension) with binary black hole systems that are extremely well localized in the sky, also called golden dark sirens. Bright sirens like binary neutron star systems can also help resolve the tension if both the GW and the following electromagnetic counterpart are detected. In this work, we show that neutron star-black hole (NSBH) mergers can act both as golden dark sirens as well as bright sirens, thus, assigning them the term grey sirens. We assess the potential of using NSBH mergers to measure H0 and find that the Voyager network might be able to resolve the tension in an observation span of 5 yr. The next generation networks, which include the Cosmic Explorer detectors and the Einstein Telescope will be able to measure H0 to sub-per cent level just by using NSBH mergers.

Searching For Black Holes Using Auto Differentiation

This study presents GravAD, a novel approach for detecting gravitational waves using automatic differentiation and JAX. GravAD demonstrates comparable signal-to-noise ratio and mass values to established LIGO pipelines with a significant reduction in the number of templates. Limitations include the inability to handle binary neutron star systems and some lower-mass black holes. Leveraging JAX’s acceleration, GravAD offers potential as a rapid preliminary tool for gravitational wave detection. Future work includes further optimisation of functions, exploration of alternative optimisation algorithms, real-time data analysis adaptation, and expanding the scope to handle a broader range of astrophysical sources.

Radio Observations of Six Young Type Ia Supernovae

Type Ia supernovae (SNe Ia) are important cosmological tools, probes of binary star evolution, and contributors to cosmic metal enrichment; yet, a definitive understanding of the binary star systems that produce them remains elusive. Of particular interest is the identity of the mass-donor companion to the exploding carbon–oxygen white dwarf (CO WD). In this work, we present early-time (first observation within 10 days post-explosion) radio observations of six nearby (within 40 Mpc) SNe Ia taken by the Jansky Very Large Array, which are used to constrain the presence of synchrotron emission from the interaction between ejecta and circumstellar material (CSM). The two motivations for these early-time observations are: (1) to constrain the presence of low-density winds and (2) to provide an additional avenue of investigation for those SNe Ia observed to have early-time optical/UV excesses that may be due to CSM interaction. We detect no radio emission from any of our targets. Toward our first aim, these non-detections further increase the sample of SNe Ia that rule out winds from symbiotic binaries and strongly accreting white dwarfs. and discuss the dependence on underlying model assumptions and how our observations represent a large increase in the sample of SNe Ia with low-density wind constraints. For the second aim, we present a radiation hydrodynamics simulation to explore radio emission from an SN Ia interacting with a compact shell of CSM, and find that relativistic electrons cannot survive to produce radio emission despite the rapid expansion of the shocked shell after shock breakout. The effects of model assumptions are discussed for both the wind and compact shell conclusions.

Precise Age for the Binary Star System 12 Com in the Coma Berenices Cluster

We present measurements of the interferometrically resolved binary star system 12 Com and the single giant star 31 Com in the cluster Coma Berenices. 12 Com is a double-lined spectroscopic binary system consisting of a G7 giant and an A3 dwarf at the cluster turnoff. Using an extensive radial velocity data set and interferometric measurements from the Palomar Testbed Interferometer and the Center for High Angular Resolution Astronomy array, we measured masses M 1 = 2.64 ± 0.07M ⊙ and M 2 = 2.10 ± 0.03M ⊙. Interferometry also allows us to resolve the giant and measure its size as R 1 = 9.12 ± 0.12 ± 0.01R ⊙. With the measured masses and radii, we find an age of 533 ± 41 ± 42 Myr. For comparison, we measure the radius of 31 Com to be 8.36 ± 0.15 R ⊙. Based on the photometry and radius measurements, 12 Com A is likely the most evolved bright star in the cluster, large enough to be in the red giant phase, but too small to have core helium burning. Simultaneous knowledge of 12 Com A’s mass and photometry puts strong constraints on convective core overshooting during the main-sequence phase, which in turn reduces systematic uncertainties in the age. Increased precision in measuring this system also improves our knowledge of the progenitor of the cluster white dwarf WD1216+260.

Jet-environment interplay in magnetized binary neutron star mergers

ABSTRACT GRB 170817A, the first short gamma-ray burst (sGRB) to be detected in coincidence with a gravitational wave signal, demonstrated that merging binary neutron star (BNS) systems can power collimated ultra-relativistic jets, and in turn, produce sGRBs. Moreover, it revealed that sGRB jets possess an intrinsic angular structure that is imprinted in the observable prompt and afterglow emission. Advanced numerical simulations represent the leading approach to investigate the physical processes underlying the evolution of sGRB jets breaking out of post-merger environments, and thus connect the final angular structure and energetics with specific jet launching conditions. In a previous paper, we carried out the first 3D special-relativistic hydrodynamic simulations of incipient (top-hat) sGRB jets propagating across the realistic environment resulting from a general-relativistic (GR) hydrodynamic BNS merger simulation. While the earlier work marked an important step toward a consistent end-to-end description of sGRB jets from BNS mergers, those simulations did not account for the presence of magnetic fields, which are expected to play a key role. Here, we overcome this limitation, reporting the first 3D special-relativistic magnetohydrodynamic (MHD) simulation of a magnetized (structured and rotating) sGRB jet piercing through a realistic magnetized post-merger environment, wherein the initial conditions of the latter are directly imported from the outcome of a previous GRMHD BNS merger simulation.

Reconnection-Powered Fast Radio Transients from Coalescing Neutron Star Binaries.

It is an open question whether and how gravitational wave events involving neutron stars can be preceded by electromagnetic counterparts. This Letter shows that the collision of two neutron stars with magnetic fields well below magnetar-level strengths can produce millisecond fast-radio-burst-like transients. Using global force-free electrodynamics simulations, we identify the coherent emission mechanism that might operate in the common magnetosphere of a binary neutron star system prior to merger. We predict that the emission show have frequencies in the range of 10-20GHz for magnetic fields of B^{*}=10^{11} G at the surfaces of the stars.

Signatures of quark deconfinement through the r -modes of twin stars

The observation and distinction of two compact stars with an identical mass but a different radius would be a clear sign of hadron-quark phase transition in nuclear matter. Motivated by studies searching for significant deviations in the observables of twin stars, we investigate the differences that manifest in their $r$-mode instability windows and spin-down evolution. Firstly, we obtain a set of hybrid equations of state (which predict the existence of a third stable branch of compact objects) by employing the well-known Maxwell construction within the phenomenological framework of constant speed of sound parametrization. Then, we systematically study the influence of certain parameters, such as the energy density jump (in the resulting hybrid equation of state) and the crust elasticity, on the deviations appearing in the $r$-mode instability windows and spin-down evolution of twin stars. We conclude that two stars with an identical mass and fairly similar spin frequency and temperature, may behave differently with respect to $r$-modes. Thus, the future possible detection of gravitational waves (due to unstable $r$-modes) from a star laying in the stable region of the frequency-temperature plane would be a strong indication for the existence of twin stars. Furthermore, we consider current data for the spin frequencies and temperatures of observed pulsars and compare them to the predictions made from equations of state employed in this study. We find that, depending on the transition density and the rigidness of the crust, hybrid equations of state may be a viable solution for the explanation of existing data.

Radial-velocity discovery of a second planet in the TOI-1338/BEBOP-1 circumbinary system

We report the detection of a gas-giant planet in orbit around both stars of an eclipsing binary star system that also contains the smaller, inner transiting planet TOI-1338b. The new planet, called TOI-1338/BEBOP-1c, was discovered using radial-velocity data collected with the HARPS and ESPRESSO spectrographs. Our analysis reveals it is a $65.2~\rm{M_{\oplus}}$ circumbinary planet with a period of $215.5~$days. This is the first detection of a circumbinary planet using radial-velocity observations alone, and makes TOI-1338/BEBOP-1 only the second confirmed multiplanet circumbinary system to date. We do not detect the smaller inner transiting planet with radial-velocity data, and can place an upper limit on the inner planet's mass at $21.8~\mathrm{M}_\oplus$ with $99\%$ confidence. The inner planet is the first circumbinary planet amenable for atmospheric characterisation, using the James Webb Space Telescope.

Unraveling information about supranuclear-dense matter from the complete binary neutron star coalescence process using future gravitational-wave detector networks

Gravitational waves provide us with an extraordinary tool to study the matter inside neutron stars. In particular, the postmerger signal probes an extreme temperature and density regime and will help reveal information about the equation of state of supranuclear-dense matter. Although current detectors are most sensitive to the signal emitted by binary neutron stars before the merger, the upgrades of existing detectors and the construction of the next generation of detectors will make postmerger detections feasible. For this purpose, we present a new analytical, frequency-domain model for the inspiral-merger-postmerger signal emitted by binary neutron star systems. The inspiral and merger parts of the signals are modeled with IMRPhenomD_NRTidalv2, and we describe the main emission peak of the postmerger with a three-parameter Lorentzian, using two different approaches: one in which the Lorentzian parameters are kept free, and one in which we model them via quasiuniversal relations. We test the performance of our new complete waveform model in parameter estimation analyses, studying simulated signals obtained both from our developed model and by injecting numerical relativity waveforms. We investigate the performance of different detector networks to determine the improvement that future detectors will bring to our analysis. We consider Advanced $\mathrm{LIGO}+$ and Advanced $\mathrm{Virgo}+$, KAGRA, and LIGO-India. We also study the possible impact of a detector with high sensitivity in the kilohertz band like NEMO, and finally we compare these results to the ones we obtain with third-generation detectors, the Einstein Telescope and the Cosmic Explorer.

Betelgeuse: a review

Abstract Was Betelgeuse once in a binary star system? What causes it to vary over a vast range of timescales? Why did it dim dramatically in 2020? When and how will it explode? J. Craig Wheeler and Manos Chatzopoulos present a host of challenges to both observers and theorists.

Spectroscopic Follow-up of Gaia Exoplanet Candidates: Impostor Binary Stars Invade the Gaia DR3 Astrometric Exoplanet Candidates

In this paper, we report on the follow-up of six potential exoplanets detected with Gaia astrometry and provide an overview of what is currently known about the nature of the entire Gaia astrometric exoplanet candidate sample, 72 systems in total. We discuss the primary false-positive scenario for astrometric planet detections: binary systems with alike components that produce small photocenter motions, mimicking exoplanets. These false positives can be identified as double-lined binaries (SB2) through analysis of high-resolution spectra. Doing so we find that three systems, Gaia DR3 1916454200349735680, Gaia DR3 2052469973468984192, and Gaia DR3 5122670101678217728, are indeed near-equal-mass double-star systems rather than exoplanetary systems. The spectra of the other two analyzed systems, HD 40503 and HIP 66074, are consistent with the exoplanet scenario in that no second set of lines can be found in the time series of publicly available high-resolution spectra. However, their Gaia astrometric solutions imply radial-velocity semiamplitudes ∼3 (HD 40503) and ∼15 (HIP 66074) larger than what was observed with ground-based spectrographs. The Gaia astrometry orbital solutions and ground-based radial-velocity measurements exhibit inconsistencies in six out of a total of 12 exoplanet candidate systems where such data are available, primarily due to substantial differences between observed ground-based radial-velocity semiamplitudes and those implied by the Gaia orbits. We investigated various hypotheses as to why this might be the case, and although we found no clear perpetrator, we note that a mismatch in orbital inclination offers the most straightforward explanation.

The Spatial-Temporal Evolution on County Accessibility and Economic Impact of Baoding High-Speed Railway Network

The districts and counties in the Baoding region are the subjects of this study, with an emphasis on the accessibility and economic relations between the core city, the Xiong’an New Area, and periphery districts and counties. By taking into account intracity transportation connections and passengers’ travel behavior choices, a mix of weighted average travel time, economic potential, and spatial autocorrelation analysis methodologies is applied. The accessibility modifications and evolution of the spatial distribution pattern of economic activity in the Baoding region as a result of the high-speed railway (HSR) construction are analyzed at multiscale. The findings indicate that (1) the accessibility level of the central city, the Xiong’an New Area, and counties in Baoding has been significantly improved, and a spatial distribution pattern of rings and branches has been formed, with the Beijing-Guangzhou and Xiong’an-Kunming directions serving as axes for expansion outward. The accessibility level is high in the east and high in the northwest. (2) The accessibility level is characterized by a high eastern component and a low western component. The economic potential of the core counties along the HSR line is substantially greater than that of the periphery counties, generating a geographical pattern of “twin stars” with the central city and the Xiong’an New Area at the apex and a diminishing circle radiating outward from the center. At the same time, due to the convergence of multiple HSR line. (3) Economic activities in Baoding districts and counties spread out more and more as the reachability time range widens. The optimal radiation range is within 1 hour. Economic activities in the Baoding region are not randomly distributed.

GANBISS: a new GPU accelerated N-body code for binary star systems

We present a GPU accelerated N-body integrator using the Bulirsch–Stoer method, called GANBISS (GPU accelerated n-body code for binary star systems). It is designed to simulate the dynamical evolution of planetesimal disks in binary star systems which contain some thousand disk objects. However, it can also be used for studies of non-interacting massless bodies where up to 50 million objects can be studied in a simulation. GANBISS shows the energy and angular momentum conservation behavior of non-symplectic integration methods. The code is written in CUDA C and can be run on NVIDIA GPUs of compute capability of at least 3.5. A comparison of GPU and CPU computations indicates a speed-up of the GPU performance of up to 100 times—depending on the number of disk objects.

The Detection Scheme and Applications of Gravitational Waves

In recent years, gravitational waves have already attracted attention as the gateway to a new era in physics since they were first directly detected and observed. This paper summarizes the development of gravitational waves from the first proposed to the present and the main observation methods, as well as the main uses and significance of the detection of them. To be specific, in this paper, the most popular laser interferometer technique for the detection based on Michelson interferometer is discussed, and several purposes of the detection of gravitational waves are given. The detection signatures are available to adopt to the analysis of the collision of binary star systems. Gravitational radiation or primordial gravitational radiation can carry more information about black holes or the Big Bang than electromagnetic waves. The gravitational wave astronomy created by gravitational waves has opened a new horizon for astronomers to explore the universe, and the detection of them is an integral part of the future development of physics and astronomy. To sum up, these results shed light on guiding further exploration of gravitational waves detection as well as applications of them.