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Journal articles on the topic 'Binary star structure'
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1
S. Brickhouse, Nancy. "Structures of Binary Star Coronae." Symposium - International Astronomical Union 219 (2004): 199–210. http://dx.doi.org/10.1017/s0074180900182129.
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Stellar coronae in binary star systems offer both a puzzle and an opportunity. We might expect that large magnetic loop structures on close binaries, such as RS CVn systems and contact binaries, would show evidence for interactions between the stars. While some radio studies support this scenario, there is surprisingly little evidence from EUV and X-ray observations for differences between binary and single star systems. Meanwhile, the binary systems offer observational opportunities through rotational modulation and eclipses of flaring and non-flaring regions. Localizing the sources of coronal emission is key to making the magnetic connection to the underlying photosphere. We discuss the structure of stellar coronae from the perspective of studies of binary systems.
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Podsiadlowski, Philipp. "Binary Effects on Supernovae." Proceedings of the International Astronomical Union 9, S296 (2013): 45–52. http://dx.doi.org/10.1017/s1743921313009216.
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AbstractHere we review how binary interactions affect the final pre-supernova structure of massive stars and the resulting supernova explosions. (1) Binary-induced mass loss and mass accretion determine the final envelope structure, the mass, radius and chemical composition, which are mainly responsible for the supernova appearance and supernova (sub-)type. (2) Mass loss can also drastically change the core evolution and hence the final fate of a star; specifically, around 10 M⊙, it determines whether a star explodes in a supernova or forms a white dwarf, while for larger masses it can dramatically increase the minimum main-sequence mass above which a star is expected to collapse to a black hole. (3) Mass loss before the supernova directly affects the circumstellar medium (CSM) which can affect the supernova spectrum (e.g. account for the IIn phenomenon), produce powerful radio emission and, in extreme cases, lead to a strong interaction with the supernova ejecta and thus strongly modify the lightcurve shape; it may even be responsible for some of the superluminous supernovae that have recently been discovered.
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Liu, Boyuan, and Volker Bromm. "Gravitational waves from the remnants of the first stars in nuclear star clusters." Monthly Notices of the Royal Astronomical Society 506, no. 4 (2021): 5451–67. http://dx.doi.org/10.1093/mnras/stab2028.
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ABSTRACT We study Population III (Pop III) binary remnant mergers in nuclear star clusters (NSCs) with a semi-analytical approach for early structure formation. Within this framework, we keep track of the dynamics of Pop III binary (compact object) remnants during cosmic structure formation, and construct the population of Pop III binary remnants that fall into NSCs by dynamical friction of field stars. The subsequent evolution within NSCs is then derived from three-body encounters and gravitational-wave (GW) emission. We find that 7.5 per cent of Pop III binary remnants will fall into the centres ($\lt 3\ \rm pc$) of galaxies. About 5–50 per cent of these binaries will merge at z > 0 in NSCs, including those with very large initial separations (up to 1 pc). The merger rate density (MRD) peaks at z ∼ 5–7 with ${\sim} 0.4\!-\!10\ \rm yr^{-1}\ \rm Gpc^{-3}$, leading to a promising detection rate of ${\sim} 170\!-\!2700\ \rm yr^{-1}$ for third-generation GW detectors that can reach z ∼ 10. Low-mass (${\lesssim} 10^{6}\ \rm M_{\odot }$) NSCs formed at high redshifts (z ≳ 4.5) host most (≳90 per cent) of our mergers, which mainly consist of black holes (BHs) with masses of ${\sim} 40\!-\!85\ \rm M_{\odot }$, similar to the most massive BHs found in LIGO events. Particularly, our model can produce events like GW190521 involving BHs in the standard mass gap for pulsational pair-instability supernovae with an MRD of ${\sim} 0.01\!-\!0.09\ \rm yr^{-1}\ Gpc^{-3}$ at z ∼ 1, consistent with that inferred by LIGO.
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Nagase, Fumiaki. "Photoionized Plasmas in X-Ray Binary Pulsars: ASCA Observations." Symposium - International Astronomical Union 188 (1998): 101–4. http://dx.doi.org/10.1017/s0074180900114524.
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Massive X-ray binary pulsars have often evolved early-type companion stars which emanate strong stellar winds. X-rays emitted from the accreting neutron star irradiate and ionize the surrounding stellar wind, thus forming a photoionized sphere surrounding the neutron star. The photoionization structure of matter surrounding the neutron star was calculated by Hatchett and McCray (1977) and McCray et al. (1984), for Cen X-3 and Vela X-1 respectively.
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Patton, Rachel A., and Tuguldur Sukhbold. "Towards a realistic explosion landscape for binary population synthesis." Monthly Notices of the Royal Astronomical Society 499, no. 2 (2020): 2803–16. http://dx.doi.org/10.1093/mnras/staa3029.
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ABSTRACT A crucial ingredient in population synthesis studies involving massive stars is the determination of whether they explode or implode in the end. While the final fate of a massive star is sensitive to its core structure at the onset of collapse, the existing binary population synthesis studies do not reach core collapse. Instead, they employ simple prescriptions to infer their final fates without knowing the pre-supernova core structure. We explore a potential solution to this problem by treating the carbon-oxygen (CO) core independently from the rest of the star. Using the implicit hydrodynamics code $\mathrm{\tt {KEPLER}}$, we have computed an extensive grid of 3496 CO-core models from a diverse range of initial conditions, each evolved from carbon ignition until core collapse. The final core structure, and thus the explodability, varies non-monotonically and depends sensitively on both the mass and initial composition of the CO core. Although bare CO cores are not perfect substitutes for cores embedded in massive stars, our models compare well both with $\mathrm{\tt {MESA}}$ and full hydrogenic and helium star calculations. Our results can be used to infer the pre-supernova core structures from population synthesis estimates of CO-core properties, thus to determine the final outcomes based on the results of modern neutrino-driven explosion simulations. A sample application is presented for a population of Type-IIb supernova progenitors.
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Ionov, D. E., D. V. Bisikalo, P. V. Kaygorodov, and V. I. Shematovich. "Gas Dynamic Simulation of the Star-Planet Interaction using a Binary Star Model." Proceedings of the International Astronomical Union 7, S282 (2011): 545–46. http://dx.doi.org/10.1017/s1743921311028341.
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AbstractWe have performed numerical simulations of the interaction between a “hot Jupiter” planet and gas of the stellar wind using a numerical code developed for investigations of binary stars. With this code, we have modeled the structure of the gaseous flow in the system HD 209458. The results have been used to explain observations of this system performed with the COS instrument on-board the HST.
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Kovaleva, D., P. Kaygorodov, O. Malkov, B. Debray, and E. Oblak. "Binary star DataBase BDB development: Structure, algorithms, and VO standards implementation." Astronomy and Computing 11 (June 2015): 119–25. http://dx.doi.org/10.1016/j.ascom.2015.02.007.
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Reed, Phillip A. "The Effects of Eccentric Accretion Structures on the Light Curves of Interacting Algol-type Binary Stars." Proceedings of the International Astronomical Union 7, S282 (2011): 325–26. http://dx.doi.org/10.1017/s1743921311027736.
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AbstractThe light curves of many Algol-type binary stars are complicated with strange variations. Secular variations are due to the transient nature of the accretion structure, while the phase-dependent features, such as outside-of-eclipse dips, are likely geometrical effects of the accretion structure eclipsing the primary star. Presented here is a model of the ultraviolet light curve of R Arae that explains these variations through the combination of an eccentric accretion structure and the system's orbital inclination.The orbital period of R Ara is 4.4 days, which is too long to allow for direct impact of the mass transfer stream onto the primary star, but not long enough for a stable accretion disk to form. Such intermediate-period Algols are good candidates in which to find transient and eccentric accretion structures. Other examples of interacting Algols that exhibit outside-of-eclipse dips in their light curves include RV Oph (Porb.=3.7 days) and Y Psc (Porb.=3.9 days).In order to more accurately model eccentric accretion structures with synthetic light curves, especially at visible (and longer) wavelengths, more work must be done to account for emission by the parts of the accretion structure that are not in the line of sight to the primary star. The model presented here accounts only for the eclipsing regions of the accretion structure.
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McCray, Richard. "Compact Binary X-Ray Sources." International Astronomical Union Colloquium 89 (1986): 184–97. http://dx.doi.org/10.1017/s0252921100086085.
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AbstractCompact binary X-ray sources include white dwarfs, neutron stars, and black holes that are accreting matter from a companion star. The X-ray emission from these systems is produced by the accreting matter as it flows through an accretion disk and strikes the surface of the compact object. The emitting regions have opacities dominated by electron scattering, and radiation pressure is likely to play an important role in the hydrodynamics. Strong magnetic fields greatly modify the hydrodynamics and radiation transfer in the pulsating neutron star sources. Accretion disks have complex structure, including an electron scattering corona, a cool outer region, and possibly a thick torus in their inner region. The structure and stability properties of accretion disks are only partially understood. Major problems exist with the interpretation of the spectra and luminosities of the X-ray burst sources. The pulsed X-ray emission from the pulsating binary X-ray sources probably comes from “mounds” of accreting gas at the magnetic poles of neutron stars, in which the accreting matter is decelerated by radiation pressure. The physics of these systems is reviewed, with an emphasis on problems for which hydrodynamical simulations may be especially useful.
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Hummel, W., S. Štefl та Th Rivinius. "The Circumstellar Structure of the Be Shell Star ϕ Per". International Astronomical Union Colloquium 175 (2000): 577–80. http://dx.doi.org/10.1017/s0252921100056554.
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AbstractWe present phase resolved spectra of the Be binary ϕ Per. It is shown that orbital phase variations of the He I line profiles are due to a sector emission region in the circumprimary disk facing the secondary. The increasing asymmetry of Fe II emission lines indicates a density inhomogeneity in the circumprimary disk that developed after 1996.
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Ebrová, I., M. Bílek, M. K. Yıldız, and J. Eliášek. "NGC 4993, the shell galaxy host of GW170817: constraints on the recent galactic merger." Astronomy & Astrophysics 634 (February 2020): A73. http://dx.doi.org/10.1051/0004-6361/201935219.
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Context. NGC 4993 is the shell galaxy host of the GRB170817A short gamma-ray burst and the GW170817 gravitational-wave event produced during a binary-neutron-star coalescence. Aims. The galaxy shows signs, including the stellar shells, that it has recently accreted a smaller, late-type galaxy. The accreted galaxy might be the original host of the binary neutron star. Methods. We measured the positions of the stellar shells of NGC 4993 in an HST/ACS archival image and use the shell positions to constrain the time of the galactic merger. Results. According to the analytical model of the evolution of the shell structure in the expected gravitational potential of NGC 4993, the galactic merger happened at least 200 Myr ago, with a probable time roughly around 400 Myr, and the estimates higher than 600 Myr being improbable. This constitutes the lower limit on the age of the binary neutron star, because the host galaxy was probably quenched even before the galactic merger, and the merger has likely shut down the star formation in the accreted galaxy. We roughly estimate the probability that the binary neutron star originates in the accreted galaxy to be around 30%.
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Cyr, Isabelle H., C. E. Jones, A. C. Carciofi, C. Steckel, C. Tycner, and A. T. Okazaki. "Spiral density enhancements in Be binary systems." Monthly Notices of the Royal Astronomical Society 497, no. 3 (2020): 3525–36. http://dx.doi.org/10.1093/mnras/staa2176.
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ABSTRACT We use a smoothed particle hydrodynamics (SPH) code to examine the effects of a binary companion on a Be star disc for a range of disc viscosities and misalignment angles, i.e. the angle between the orbital plane and the primary star’s spin axis. The density structures in the disc due to the tidal interaction with the binary companion are investigated. Expanding on our previous work, the shape and density structure of density enhancements due to the binary companion are analysed and the changes in observed interferometric features due to these orbiting enhancements are also predicted. We find that larger misalignment angles and viscosity values result in more tightly wound spiral arms with densities that fall-off more slowly with radial distance from the central star. We show that the orbital phase has very little effect on the structure of the spiral density enhancements. We demonstrate that these spiral features can be detected with an interferometer in H α and K-band emission. We also show that the spiral features affect the axis ratios determined by interferometry depending on the orientation of these features and the observer. For example, our simulations show that the axis ratios can vary by 20 per cent for our co-planar binary disc system depending on the location of the disc density enhancements.
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Castellanos-Ramírez, A., A. Rodríguez-González, Z. Meliani, P. R. Rivera-Ortiz, A. C. Raga, and J. Cantó. "Two-wind interactions in binaries with two orbiting giant stars." Monthly Notices of the Royal Astronomical Society 507, no. 3 (2021): 4044–52. http://dx.doi.org/10.1093/mnras/stab2373.
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ABSTRACT Some red giant envelopes present spiral structures (seen either in dust-scattered stellar continuum or in molecular line emission), the most striking example probably being AFGL 3068. This object has been modeled (both analytically and numerically) in terms of a wind ejected from a star in orbit around a binary companion. We revisit both analytical models and 3D simulations of a wind from an orbiting red giant star, and extend the numerical simulations to the case of a binary with two red giants with strong winds. We find that most two-wind models on the orbital plane show a ‘double spiral’ structure close to the binary source, and that these two arms merge into a single spiral structure at larger distances. However, for the case of a binary with two identical winds, the two spiral arms are still present at large distances from the binary source. We also find that for models of two (not identical) dynamically important winds, a region close to the orbital plane has material from both winds. Also, an approximately conical region centered on the orbital axis is filled exclusively by the wind with larger momentum rate. These two structures lead to morphologies reminiscent of the so-called ‘hour glass’ planetary nebulae. Finally, we find that increasing wind velocity disparities lead to the formation of clumpy structures along the spiral arms. Observations of ‘clumpy spirals’ are therefore likely to indicate the presence of two strong winds from the stars in the central binary system.
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Hanauske, Matthias, Jan Steinheimer, Anton Motornenko, et al. "Neutron Star Mergers: Probing the EoS of Hot, Dense Matter by Gravitational Waves." Particles 2, no. 1 (2019): 44–56. http://dx.doi.org/10.3390/particles2010004.
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Gravitational waves, electromagnetic radiation, and the emission of high energy particles probe the phase structure of the equation of state of dense matter produced at the crossroad of the closely related relativistic collisions of heavy ions and of binary neutron stars mergers. 3 + 1 dimensional special- and general relativistic hydrodynamic simulation studies reveal a unique window of opportunity to observe phase transitions in compressed baryon matter by laboratory based experiments and by astrophysical multimessenger observations. The astrophysical consequences of a hadron-quark phase transition in the interior of a compact star will be focused within this article. Especially with a future detection of the post-merger gravitational wave emission emanated from a binary neutron star merger event, it would be possible to explore the phase structure of quantum chromodynamics. The astrophysical observables of a hadron-quark phase transition in a single compact star system and binary hybrid star merger scenario will be summarized within this article. The FAIR facility at GSI Helmholtzzentrum allows one to study the universe in the laboratory, and several astrophysical signatures of the quark-gluon plasma have been found in relativistic collisions of heavy ions and will be explored in future experiments.
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Guinan, Edward F., Petr Harmanec, and William Hartkopf. "Introduction & Overview to Symposium 240: Binary Stars as Critical Tools and Tests in Contemporary Astrophysics." Proceedings of the International Astronomical Union 2, S240 (2006): 5–16. http://dx.doi.org/10.1017/s1743921307003730.
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AbstractAn overview is presented of the many new and exciting developments in binary and multiple star studies that were discussed at IAU Symposium 240. Impacts on binary and multiple star studies from new technologies, techniques, instruments, missions and theory are highlighted. It is crucial to study binary and multiple stars because the vast majority of stars (>60%) in our Galaxy and in other galaxies consist, not of single stars, but of double and multiple star systems. To understand galaxies we need to understand stars, but since most are members of binary and multiple star systems, we need to study and understand binary stars. The major advances in technology, instrumentation, computers, and theory have revolutionized what we know (and also don't know) about binary and multiple star systems. Data now available from interferometry (with milliarcsecond [mas] and sub-mas precisions), high-precision radial velocities (∼1-2 m/s) and high precision photometry (<1–2 milli-mag) as well as the wealth of new data that are pouring in from panoramic optical and infrared surveys (e.g., > 10,000 new binaries found since 1995), have led to a renaissance in binary star and multiple star studies. For example, advances have lead to the discovery of new classes of binary systems with planet and brown dwarf components (over 200 systems). Also, extremely valuable data about binary stars are available across the entire electromagnetic spectrum — from gamma-ray to IR space missions and from the ground using increasingly more powerful and plentiful optical and radio telescopes as well as robotic telescopes. In the immediate future, spectral coverage could even be extended beyond the radio to the first detection of gravity waves from interacting close binaries. Also, both the quality and quantity of data now available on binary and multiple stars are making it possible to gain unprecedented new insights into the structure, and formation and evolution of binary stars, as well as providing valuable astrophysical information (like precise stellar masses, radii, ages, luminosities and distances) to test and constrain current astrophysical theory. These major advances permit tests of current theories and ideas in stellar astrophysics and provide the foundations for the next steps in modeling and improvements in theory to be taken.
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Hilditch, Ron W., Tim J. Harries, and Ian D. Howarth. "Eclipsing Spectroscopic Binaries in the SMC." Highlights of Astronomy 13 (2005): 455. http://dx.doi.org/10.1017/s153929960001621x.
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The OGLE survey of the SMC has discovered ~1500 eclipsing binaries thereby providing an excellent platform to study the evolution of close binary systems through case A and case B mass-exchange processes. The complementary spectroscopic radial-velocity studies of these binaries are now in progress and are revealing many interesting systems which challenge current theoretical models of close binary star evolution. These studies also provide excellent direct determinations of distances to these binary stars leading to an improved understanding of the mean distance to the SMC and its 3-D structure. Comparisons between these binary-star distances and other methods of determining the mean distance to the SMC will also be made.
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Hartmann, Lee. "Testing the Paradigm of Low Mass Star Formation." Symposium - International Astronomical Union 221 (2004): 201–12. http://dx.doi.org/10.1017/s0074180900241600.
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Protostellar core formation is probably much more dynamic, and magnetic fields are probably much less important, than has been previously assumed in the standard model of low-mass star formation. This revised picture has important consequences: it is easier to understand the observed rapidity of star formation in molecular clouds; cores are more likely to have structures favoring high infall rates at early times, helping to explain the differences between Class 0 and Class I protostars; and core structure and asymmetry will strongly favor post-collapse fragmentation into binary and multiple stellar systems.
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Song, Ren, Xiangcun Meng, Philipp Podsiadlowski, and Yingzhen Cui. "Structure of a massive common envelope in the common-envelope wind model for Type Ia supernovae." Astronomy & Astrophysics 633 (January 2020): A41. http://dx.doi.org/10.1051/0004-6361/201936526.
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Context. Although Type Ia supernovae (SNe Ia) are important in many astrophysical fields, the nature of their progenitors is still unclear. A new version of the single-degenerate model has been developed recently, the common-envelope wind (CEW) model, in which the binary is enshrouded in a common envelope (CE) during the main accretion phase. This model is still in development and has a number of open issues, for example what is the exact appearance of such a system during the CE phase? Aims. In this paper we investigate this question for a system with a massive CE. Methods. We use a thermally pulsing asymptotic giant branch (TPAGB) star with a CO core of 0.976 M⊙ and an envelope of 0.6 M⊙ to represent the binary system. The effects of the companion’s gravity and the rotation of the CE are mimicked by modifying the gravitational constant. The energy input from the friction between the binary and the CE is taken into account by an extra heating source. Results. For a thick envelope, the modified TPAGB star looks similar to a canonical TPAGB star but with a smaller radius, a higher effective temperature, and a higher surface luminosity. This is primarily caused by the effect of the companion’s gravity, which is the dominant factor in changing the envelope structure. The mixing length at the position of the companion can be larger than the local radius, implying a breakdown of mixing-length theory and suggesting the need for more turbulence in this region. The modified TPAGB star is more stable than the canonical TPAGB star and the CE density around the companion is significantly higher than that assumed in the original CEW model. Conclusions. Future work will require the modelling of systems with lower envelope masses and the inclusion of hydrodynamical effects during the CE phase.
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Sargsyan, V. V., H. Lenske, G. G. Adamian, and N. V. Antonenko. "From dinuclear systems to close binary stars: Application to mass transfer." International Journal of Modern Physics E 27, no. 07 (2018): 1850063. http://dx.doi.org/10.1142/s0218301318500635.
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Applying the microscopic nuclear physics ideas to macroscopic stellar systems, we study the evolution of the compact di-stars in mass asymmetry (transfer) coordinate. Depending on the internal structure of constituent stars, the initial mass asymmetry, total mass, and orbital angular momentum, the close di-star system can either exist in symmetric configuration or fuse into mono-star. The limitations for the formation of stable symmetric binary stars are analyzed.
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M. Walter, Frederick. "Resolving Atmospheric Structure in V471 Tauri." Symposium - International Astronomical Union 219 (2004): 233–37. http://dx.doi.org/10.1017/s0074180900182166.
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The K2V-DA binary V471 Tau has an extended atmosphere. By using the DA white dwarf as a probe, we can probe the atmosphere along the line of sight to the white dwarf with a spatial resolution of order 10,000 km. We observe absorption lines from C II through N V in absorption against the DA photospheric continuum. The velocities are those of gas in co-rotation with the K star.
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Bermúdez-Bustamante, Luis C., G. García-Segura, W. Steffen, and L. Sabin. "AGB winds in interacting binary stars." Monthly Notices of the Royal Astronomical Society 493, no. 2 (2020): 2606–17. http://dx.doi.org/10.1093/mnras/staa403.
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ABSTRACT We perform numerical simulations to investigate the stellar wind from interacting binary stars. Our aim is to find analytical formulae describing the outflow structure. In each binary system the more massive star is in the asymptotic giant branch (AGB) and its wind is driven by a combination of pulsations in the stellar surface layers and radiation pressure on dust, while the less massive star is in the main sequence. Time averages of density and outflow velocity of the stellar wind are calculated and plotted as profiles against distance from the centre of mass and colatitude angle. We find that mass is lost mainly through the outer Lagrangian point L2. The resultant outflow develops into a spiral at low distances from the binary. The outflowing spiral is quickly smoothed out by shocks and becomes an excretion disc at larger distances. This leads to the formation of an outflow structure with an equatorial density excess, which is greater in binaries with smaller orbital separation. The pole-to-equator density ratio reaches a maximum value of ∼105 at Roche lobe overflow state. We also find that the gas stream leaving L2 does not form a circumbinary ring for stellar mass ratios above 0.78, when radiation pressure on dust is taken into account. Analytical formulae are obtained by curve fitting the two-dimensional, azimuthally averaged density and outflow velocity profiles. The formulae can be used in future studies to set-up the initial outflow structure in hydrodynamic simulations of common-envelope evolution and formation of planetary nebulae.
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Saraswat, Priyamvada, and Krishna M. V. Apparao. "Be star disk structure as implied by X-ray observations." Symposium - International Astronomical Union 162 (1994): 213–15. http://dx.doi.org/10.1017/s0074180900214897.
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Compared to several other Be/X-ray binaries, 4U1907+09 has been observed more frequently due to the fact that it is found in an ‘on’ state more often. It also has a short orbital period of ~ 8 days as compared to the long orbital periods commonly found in these binaries. But despite the attention it has received, the exact nature of the primary remains elusive. While some observers maintain it to be a Be/X-ray binary, others prefer to put it into the class of OB supergiants.
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SIGALOTTI, LEONARDO DI G., and JAIME KLAPP. "GRAVITATIONAL COLLAPSE AND FRAGMENTATION OF MOLECULAR CLOUD CORES." International Journal of Modern Physics D 10, no. 02 (2001): 115–211. http://dx.doi.org/10.1142/s0218271801000706.
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The detected multiplicity of main-sequence and pre-main-sequence stars along with the emerging evidence for binary and multiple protostars, imply that stars may ultimately form by fragmentation of collapsing molecular cloud cores. These discoveries, coupled with recent observational knowledge of the structure of dense cloud cores and of the properties of young binary stars, provide serious constraints to the theory of star formation. Most theoretical progress in the field of star formation is largely based on numerical calculations of the early collapse and fragmentation of protostellar clouds. Although these models have been quite successful at predicting the formation of binary protostars, a direct comparison between theory and observations has not yet been established. The results of recent observations as well as of early and recent analytic and numerical models, on which the present theory of star formation is based, are reviewed here in a self-consistent manner.
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Poblete, Pedro P., Josh Calcino, Nicolás Cuello, et al. "Binary-induced spiral arms inside the disc cavity of AB Aurigae." Monthly Notices of the Royal Astronomical Society 496, no. 2 (2020): 2362–71. http://dx.doi.org/10.1093/mnras/staa1655.
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ABSTRACT In this work we demonstrate that the inner spiral structure observed in AB Aurigae can be created by a binary star orbiting inside the dust cavity. We find that a companion with a mass-ratio of 0.25, semimajor axis of 40 au, eccentricity of 0.5, and inclination of 90° produces gaseous spirals closely matching the ones observed in 12CO (2-1) line emission. Based on dust dynamics in circumbinary discs (Poblete, Cuello & Cuadra 2019), we constrain the inclination of the binary with respect to the circumbinary disc to range between 60° and 90°. We predict that the stellar companion is located roughly 0.18 arcsec from the central star towards the east-southeast, above the plane of the disc. Should this companion be detected in the near future, our model indicates that it should be moving away from the primary star at a rate of 6 mas yr−1 on the plane of the sky. Since our companion is inclined, we also predict that the spiral structure will appear to change with time, and not simply corotate with the companion.
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Aerts, Conny. "Asteroseismology of Close Binary Stars." Proceedings of the International Astronomical Union 2, S240 (2006): 432–41. http://dx.doi.org/10.1017/s1743921307004413.
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AbstractIn this review paper, we summarise the goals of asteroseismic studies of close binary stars. We first briefly recall the basic principles of asteroseismology, and highlight how the binarity of a star can be an asset, but also a complication, for the interpretation of the stellar oscillations. We discuss a few sample studies of pulsations in close binaries and summarise some case studies. This leads us to conclude that asteroseismology of close binaries is a challenging field of research, but with large potential for the improvement of current stellar structure theory. Finally, we highlight the best observing strategy to make efficient progress in the near future.
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Zwitter, Tomaž, Sandro D'Odorico, Tom Oosterloo, and Massimo Calvani. "On the Masses and on the Mass Transfer in the Interactive Binary SS 433." Symposium - International Astronomical Union 151 (1992): 465–67. http://dx.doi.org/10.1017/s0074180900122739.
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Recent spectroscopic observations of the interactive binary SS 433 with the ESO's New Technology Telescope show that the compact object is a neutron star. We note that the huge mass transfer rate (which may well be the reason for the uniqueness of SS 433) suggests that a significant fraction of the mass lost from the normal star actually settles on the neutron star. This may have important consequences for the structure of the accretion disk and for the formation of jets in this peculiar system.
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Wijers, Ralph A. M. J. "Diagnosing Structure and Evolution of Clusters with Neutron Star Binaries." Symposium - International Astronomical Union 174 (1996): 203–12. http://dx.doi.org/10.1017/s0074180900001546.
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A key problem in using binaries as a tool for diagnosing cluster evolution is that the tool itself is not very well understood. The theory of binary evolution, despite real successes that can be exploited, has serious problems in many areas relevant to cluster evolution. At least as important but often neglected are connective problems, which arise when theoretical model binaries need to be related to observed classes of object, which often requires poorly understood parts of their physics which can be quite irrelevant to their bulk properties. I shall discuss these issues in general briefly, and then illustrate them with the specific example of X-ray binaries and millisecond pulsars.
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Chatterjee, Tapan K. "Enhanced Star Formation rates in Binary Interacting Elliptical Galaxies." Symposium - International Astronomical Union 164 (1995): 452. http://dx.doi.org/10.1017/s0074180900109623.
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We study the stellar orbits, as a function of the binary motion of two identical ellipticals, under initial conditions marginally sufficient for strong interaction. The stars were initially given circularly symmetric velocities. The tidal effects cause a redistribution of stellar orbits, resulting in crowding of stars in shells; the same attaining its maximum intensity slightly after a pericentric passage. As the galaxies recede, the structure disperses gradually by expanding; but is restored, intensified and forms at a shorter radial distance as the galaxies return for a subsequent approach in a shrinking orbit. We give the stellar positions, projected perpendicular to the orbital plane, shortly after the first (t≈0.5) and second (t≈6) pericentric passages in the figures; (time being given in dimensionless units corresponding to mass=l, radius=l, G=4.50). On the basis of the cooling gas inflow model, the gas will be compressed and shocked in these regions of enhanced stellar density, leading to bursts of star formation. The interval between the two successive starbursts is found to be of the same order as the trapping time needed by the galaxy to incorporate the gas ejected by stars in its cooling flow.
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Okazaki, Atsuo T., Shigehiro Nagataki, Tsuguya Naito та ін. "Interaction between the Be star and the compact companion in TeV γ-ray binaries". Proceedings of the International Astronomical Union 6, S272 (2010): 628–29. http://dx.doi.org/10.1017/s174392131101163x.
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AbstractWe report on the results from 3-D SPH simulations of TeV binaries with Be stars. Since there is only one TeV binary (B 1259-63) where the nature of the compact companion has been established, we mainly focus on this Be-pulsar system. From simulations of B 1259-63 around periastron, we find that the pulsar wind dominates the Be-star wind and strips off an outer part of the Be-star disk, causing a strongly asymmetric, phase-dependent structure of the circumstellar material around the Be star. Such a large modulation may be detected by optical, IR, and/or UV observations at phases near periastron. We also discuss the results from simulations of another TeV binary LS I+61 303, for which the nature of the compact object is not yet known.
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Qin, Y., T. Fragos, G. Meynet, J. Andrews, M. Sørensen, and H. F. Song. "The spin of the second-born black hole in coalescing binary black holes." Astronomy & Astrophysics 616 (August 2018): A28. http://dx.doi.org/10.1051/0004-6361/201832839.
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Context. Various binary black hole formation channels have been proposed since the first gravitational event GW150914 was discovered by the Advanced Laser Interferometer Gravitational-Wave Observatory (AdLIGO). The immediate progenitor of the binary black hole is a close binary system composed of a black hole and a helium star, which can be the outcome of the classical isolated binary evolution through the common envelope, or alternatively of the massive close evolution through chemically homogeneous channel. Aims. We study the spin angular momentum evolution of the helium star in order to constrain the spin of the second-born black hole. This work focuses on the common envelope formation channel, however, some of our conclusions are also relevant for the chemically homogeneous evolution channel. Methods. We perform detailed stellar structure and binary evolution calculations that take into account, mass-loss, internal differential rotation, and tidal interactions between the helium star and the black hole companion, where we also calculate the strength of the tidal interactions from first principles based on the structure of the helium stars. We systematically explore the parameter space of initial binary properties, including initial black hole and helium star masses, initial rotation of the helium star as well as metallicity. Results. We argue that the natal spin of the first-born black hole through the common envelope scenario is negligible (≲0.1), and therefore the second-born black hole’s spin dominates the measured effective spin, χeff, from gravitational wave events of double black hole mergers. We find that tides can be only important when orbital periods are shorter than 2 days. Upon core collapse, the helium star produces a black hole (the second-born black hole in the system) with a spin that can span the entire range from zero to maximally spinning. We show that the bimodal distribution of the spin of the second-born black hole obtained in recent papers is mainly due to oversimplifying assumptions. We find an anti-correlation between the merging timescale of the two black holes, Tmerger, and the effective spin χeff. Finally, we provide new prescriptions for the tidal coefficient E2 for both H-rich and the He-rich stars. Conclusions. To understand the spin of the second-born black hole, careful treatment of both tides and stellar winds is needed. We predict that, with future improvements to AdLIGO’s sensitivity, the sample of merging binary black hole systems will show an overdensity of sources with positive but small χeff originating from lower-mass black hole mergers born at low redshift.
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Manilova (Volkova), G. V. "The Gaseous Envelope Structure of the Eclipsing Binary System V448 Cyg." International Astronomical Union Colloquium 135 (1992): 333–35. http://dx.doi.org/10.1017/s0252921100006710.
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V448 Cyg (HD 190967 = BD+34°3871) represents rather an uncommon case, where the primary component (indicated by stronger lines in the combined spectrum) is the star exhibiting mass loss. The system has a circumstellar envelope, formed by mass flow from a primary component filling its Roche lobe, and by a stellar wind that is stimulated by the duplicity of this system of two hot stars (BO Ib + O9.5 V — see Glazunova et al. 1963). Ultraviolet, polarimetric, and spectral observations of V448 Cyg permitted us to form a model of the structure and parameters of this system’s circumstellar envelope.
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Ergma, E., M. J. Sarna, and J. Antipova. "An Evolutionary Scenario for Short Period (≤10 Days) Millisecond Binary Pulsars." International Astronomical Union Colloquium 158 (1996): 473–74. http://dx.doi.org/10.1017/s0252921100039476.
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We present numerical calculations that simulate the evolution of a low mass (1M⊙) star transfering mass to a compact object (Muslimov & Sarna 1993; Ergma & Sarna 1996). Mass transfer starts when the secondary turns off the main sequence (having a small helium core). We have calculated 14 evolutionary sequences with the assumption of non-conservative or conservative evolution. We can conclude that near the bifurcation point the evolution is very sensitive to: (i) the assumption of conservative or non-conservative evolution, (ii) the structure of the mass losing star. Small changes in the initial period when the secondary fills its Roche lobe will lead to large changes in the final period and final mass of the remnant. Presently there are 40 known low-mass binary pulsars (LMBP). The evolutionary scenario for the wider systems (10 < Porb(d) < 1000) is connected with that of wide low-mass X-ray binaries (LMXB) in which the donor star will fill its Roche lobe after helium core formation.
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Rivinius, Th, D. Baade, P. Hadrava, M. Heida, and R. Klement. "A naked-eye triple system with a nonaccreting black hole in the inner binary." Astronomy & Astrophysics 637 (May 2020): L3. http://dx.doi.org/10.1051/0004-6361/202038020.
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Several dozen optical echelle spectra demonstrate that HR 6819 is a hierarchical triple. A classical Be star is in a wide orbit with an unconstrained period around an inner 40 d binary consisting of a B3 III star and an unseen companion in a circular orbit. The radial-velocity semi-amplitude of 61.3 km s−1 of the inner star and its minimum (probable) mass of 5.0 M⊙ (6.3 ± 0.7 M⊙) imply a mass of the unseen object of ≥4.2 M⊙ (≥5.0 ± 0.4 M⊙), that is, a black hole (BH). The spectroscopic time series is stunningly similar to observations of LB-1. A similar triple-star architecture of LB-1 would reduce the mass of the BH in LB-1 from ∼70 M⊙ to a level more typical of Galactic stellar remnant BHs. The BH in HR 6819 probably is the closest known BH to the Sun, and together with LB-1, suggests a population of quiet BHs. Its embedment in a hierarchical triple structure may be of interest for models of merging double BHs or BH + neutron star binaries. Other triple stars with an outer Be star but without BH are identified; through stripping, such systems may become a source of single Be stars.
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Randall, S. K., A. Trejo, E. M. L. Humphreys, et al. "Discovery of a complex spiral-shell structure around the oxygen-rich AGB star GX Monocerotis." Astronomy & Astrophysics 636 (April 2020): A123. http://dx.doi.org/10.1051/0004-6361/201935787.
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The circumstellar envelopes of asymptotic giant branch (AGB) stars exhibit a wide range of morphologies and chemical compositions that can be exploited to unravel their mass-loss history as well as binary status. Here, we present ALMA Band 6 observations centred upon the oxygen-rich, high mass-loss rate AGB star GX Mon. The resulting CO (2–1) map reveals an intricate, complex circumstellar spiral-arc structure consistent with hydrodynamical models for an AGB experiencing mass loss in a highly eccentric, close binary system with an orbital period of around 140 years. Several other transitions (including SiO, SiS, SO2, and CS) are detected in the data, however only the SO (5–4) map shows a similar – although much weaker – distribution as imaged for the CO.
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Margutti, Raffaella, and Ryan Chornock. "First Multimessenger Observations of a Neutron Star Merger." Annual Review of Astronomy and Astrophysics 59, no. 1 (2021): 155–202. http://dx.doi.org/10.1146/annurev-astro-112420-030742.
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We describe the first observations of the same celestial object with gravitational waves and light. ▪ GW170817 was the first detection of a neutron star merger with gravitational waves. ▪ The detection of a spatially coincident weak burst of gamma-rays (GRB 170817A) 1.7 s after the merger constituted the first electromagnetic detection of a gravitational wave source and established a connection between at least some cosmic short gamma-ray bursts (SGRBs) and binary neutron star mergers. ▪ A fast-evolving optical and near-infrared transient (AT 2017gfo) associated with the event can be interpreted as resulting from the ejection of ∼0.05 M⊙ of material enriched in r-process elements, finally establishing binary neutron star mergers as at least one source of r-process nucleosynthesis. ▪ Radio and X-ray observations revealed a long-rising source that peaked ∼160,d after the merger. Combined with the apparent superluminal motion of the associated very long baseline interferometry source, these observations show that the merger produced a relativistic structured jet whose core was oriented ≈20 deg from the line of sight and with properties similar to SGRBs. The jet structure likely results from interaction between the jet and the merger ejecta. ▪ The electromagnetic and gravitational wave information can be combined to produce constraints on the expansion rate of the Universe and the equation of state of dense nuclear matter. These multimessenger endeavors will be a major emphasis of future work.
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Hayasaki, Kimitake, and Atsuo T. Okazaki. "Disk Structure and Evolution Around the Neutron Star in Be/X-Ray Binaries." International Astronomical Union Colloquium 194 (July 2004): 230. http://dx.doi.org/10.1017/s0252921100152753.
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We investigate the accretion flow around the neutron star in Be/X-ray binaries, using a 3D SPH code and the data imported from simulations by Okazaki et al. (2002) and Okazaki & Hayasaki (2004) for both a coplanar system and a misaligned system in which the Bo-star disk is inclined from the binary orbital plane by 30 degrees, with a short period (Porb = 24.3 days) and moderate eccentricity (e = 0.34). We find that a non-steady accretion disk is formed around the neutron star in the misaligned case as well as in the coplanar case. The disk size in the misaligned system is significantly larger because of its higher angular momentum than that in the coplanar system. We also find that the disk also evolves via a two-stage process, which consists of the initial developing stage and the latar developed stage.
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Rosu, S., G. Rauw, K. E. Conroy, E. Gosset, J. Manfroid, and P. Royer. "Apsidal motion in the massive binary HD 152248." Astronomy & Astrophysics 635 (March 2020): A145. http://dx.doi.org/10.1051/0004-6361/201937285.
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Context. The eccentric massive binary HD 152248 (also known as V1007 Sco), which hosts two O7.5 III-II(f) stars, is the most emblematic eclipsing O-star binary in the very young and rich open cluster NGC 6231. Its properties render the system an interesting target for studying tidally induced apsidal motion. Aims. Measuring the rate of apsidal motion in such a binary system gives insight into the internal structure and evolutionary state of the stars composing it. Methods. A large set of optical spectra was used to reconstruct the spectra of the individual binary components and establish their radial velocities using a disentangling code. Radial velocities measured over seven decades were used to establish the rate of apsidal motion. We furthermore analysed the reconstructed spectra with the CMFGEN model atmosphere code to determine stellar and wind properties of the system. Optical photometry was analysed with the Nightfall binary star code. A complete photometric and radial velocity model was constructed in PHOEBE 2 to determine robust uncertainties. Results. We find a rate of apsidal motion of (1.843−0.083+0.064)° yr−1. The photometric data indicate an orbital inclination of (67.6−0.1+0.2)° and Roche-lobe filling factors of both stars of about 0.86. Absolute masses of 29.5−0.4+0.5 M⊙ and mean stellar radii of 15.07−0.12+0.08 R⊙ are derived for both stars. We infer an observational value for the internal structure constant of both stars of 0.0010 ± 0.0001. Conclusions. Our in-depth analysis of the massive binary HD 152248 and the redetermination of its fundamental parameters can serve as a basis for the construction of stellar evolution models to determine theoretical rates of apsidal motion to be compared with the observational one. In addition, the system hosts two twin stars, which offers a unique opportunity to obtain direct insight into the internal structure of the stars.
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Langer, Norbert. "Structure and evolution of massive single stars and their relevance for close binary systems." Symposium - International Astronomical Union 163 (1995): 15–23. http://dx.doi.org/10.1017/s0074180900201514.
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Differences in the evolution of massive single stars and components of massive close binary systems are investigated. While for stars above the red supergiant luminosity limit, single star and case B primary evolution merge into a single scenario, large differences for less massive stars are demonstrated to occur at the example of MZAMS = 40M⊙, concerning the various WR subtypes, the nucleosynthesis yields, and the supernova stage.
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Giannakis, O., E. T. Harlaftis, P. G. Niarchos, et al. "Mapping of the Disc Structure of the Neutron Star X-ray Binary X1822-371." Astrophysics and Space Science 304, no. 1-4 (2006): 321–22. http://dx.doi.org/10.1007/s10509-006-9142-8.
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Warren-Smith, R. F., P. W. Draper, and S. M. Scarrott. "Evidence from optical polarimetry for spiral structure in the magnetic field and cloud density around newly-formed stars." Symposium - International Astronomical Union 122 (1987): 129–30. http://dx.doi.org/10.1017/s0074180900156219.
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Deep CCD imaging of the Serpens bipolar nebula shows it to be surrounded by molecular cloud material having spiral density structure. Polarization mapping indicates that the magnetic field in this material also exhibits spiral structure and we interpret this as the remains of the magnetically-braked collapse of a protostellar cloud. A binary star system has formed in the cloud core.
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Guinan, Edward F., та Laurence E. DeWarf. "Toward Solving the Mysteries of the Exotic Eclipsing Binary є Aurigae: Two Thousand years of Observations and Future Possibilities". International Astronomical Union Colloquium 187 (2002): 121–42. http://dx.doi.org/10.1017/s0252921100001317.
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AbstractThe long period (P = 27.1 yr) eclipsing binary є Aurigae (F0 Ia + disk?) is truly an exotic star. It has a deep eclipse that lasts for nearly two years. This eclipse arises as a huge, cool, flattened disk transits the F-supergiant star. Modeling of the eclipse observations shows that the disk has a radius as large as ∼ 9 AU. Infrared observations indicate that the disk is cool with temperatures between 450 − 1000 K. Yet there is evidence of significant FUV emission also originating from the disk.At present, our knowledge of the mass and luminosity of the binary is still too uncertain to distinguish between two competing models of the system. The high mass model assumes that the F0 supergiant is a normal Pop. I star with a mass appropriate for its spectral type of M ∽ 15 M⊙. It is accompanied by a flattened disk companion with a slightly smaller mass. In this model the disk object is a young proto-stellar or protoplanetary disk. In the low mass model, the F0I star is assumed to be a bloated, old, solar mass post-AGB star. In this case the secondary object is an accretion disk with a mass of 4-5 M⊙. This disk is a remnant of postmain sequence mass transfer that occurred within the last few thousand years. In both models there are still problems explaining the object (or objects) at the center of the disk. Candidates include a pre-main sequence object, a black hole, or a close binary.In this paper we review the properties of ϵ Aurigae and discuss the advances in our understanding of this enigmatic star from observations made since its last eclipse in 1982-1984. With new technologies and advanced instrumentation it is possible that the physical properties of this puzzling binary star will be found during the next decade. Once found, then ϵ Aurigae and its eclipses can be used as a laboratory for exploring (and testing) current astrophysical concepts and theories that include rapid stages of stellar evolution, binary star evolution, and the structure and dynamics of large disks.
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Kroupa, Pavel. "The universality hypothesis: binary and stellar populations in star clusters and galaxies." Proceedings of the International Astronomical Union 6, S270 (2010): 141–49. http://dx.doi.org/10.1017/s1743921311000305.
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AbstractIt is possible to extract, from the observations, distribution functions of the birth dynamical properties of a stellar population, and to also infer that these are quite invariant to the physical conditions of star formation. The most famous example is the stellar IMF, and the initial binary population (IBP) seems to follow suit. A compact mathematical formulation of the IBP can be derived from the data. It has three broad parts: the IBP of the dominant stellar population (0.08–2M⊙), the IBP of the more-massive stars and the IBP of brown dwarfs. These three mass regimes correspond to different physical regimes of star formation but not to structure in the IMF. With this formulation of the IBP it becomes possible to synthesize the stellar-population of whole galaxies.
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Pasquali, A., A. Nota, N. Langer, R. E. Schulte-Ladbeck, and M. Clampin. "The Nebula Surrounding the B[e] Supergiant R4." International Astronomical Union Colloquium 175 (2000): 100–102. http://dx.doi.org/10.1017/s025292110005569x.
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AbstractNew, NTT observations of the B[e] supergiant RMC4 in the Small Magellanic Cloud show that the star is embedded in a circumstellar nebula, whose velocity structure is typical of a bipolar outflow. The nebula is kinematically associated with RMC4 and expanding at 100 km/s on average. Its diameter as computed from the spatial extension of its spectral lines is of 8.6″ which corresponds to a linear size of 2.4 pc and gives a dynamical age of 12500 yr. The line ratio [NII]λ6584/[SII]λ6717 indicates that the nebula is nitrogen enriched as it is expected for ejected nebulae. This is the first bipolar outflow detected around a well-established B[e] supergiant which also belongs to a binary system. The nebular morphology and chemistry are consistent with the picture of a binary merger in which RMC4 was composed by a close pair and a third star (the observed companion). The close pair merged into a single star (the present B[e] supergiant) and produced a circumstellar nebula to be later shaped by the ensuing B star wind (cf. Langer & Heger 1998).
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Sternberg, Assaf. "Evidence for Circumstellar Material in Type Ia Supernovae via Sodium Absorption Features." Proceedings of the International Astronomical Union 7, S281 (2011): 299–302. http://dx.doi.org/10.1017/s1743921312015232.
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AbstractType Ia supernovae are very good tools for measuring distances on a cosmic scale. The consensus view is that mass transfer onto a white dwarf in a close binary system leads to a thermonuclear explosion, though the nature of the mass donor is still uncertain. In the single-degenerate model it is a main-sequence star or an evolved star. In the double-degenerate model it is another white dwarf. We study the velocity structure of absorbing material along the line of sight to 35 Type Ia supernovae and find a statistical preference for blueshifted structures, likely arising in gas outflows from the supernova progenitor systems, consistent with a single-degenerate progenitor for a substantial fraction of Type Ia supernovae in nearby spiral galaxies.
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Stee, Ph, D. Bonneau, F. Morand, D. Mourard, and F. Vakili. "Current studies and future prospects in stellar-structure imaging with the GI2T." Symposium - International Astronomical Union 176 (1996): 191–98. http://dx.doi.org/10.1017/s0074180900083224.
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The capability of optical long baseline interferometry for measuring the angular diameter of stars or binary separation is now well established. However, for the imaging of photospheric disk structures one needs very long baseline interferometers operated in the multi-telescope phase-closure technique. In this paper we will stress the capability of spectro-interferometric measurements to constrain the physics of hot stars. We will report our study of the interacting binary, β Lyrae, and the mass-losing Be star γ Cassiopeiae. We will look at the interpretation of both the modulus and phase data recorded by the long baseline interferometer GI2T in the southern France. The performances and limitations of spectro-interferometric techniques will also be discussed through some of the most exciting prospects within the reach of current interferometers.
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Hurley, Jarrod R. "Models of M 67." Proceedings of the International Astronomical Union 2, no. 14 (2006): 442–43. http://dx.doi.org/10.1017/s1743921307011283.
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AbstractThe old open cluster M 67 is an ideal test case for current star cluster evolution models because of its dynamically evolved structure and rich stellar populations that show clear signs of interaction between stellar, binary and cluster evolution. Here we discuss a direct N-body model of M 67. This model of 12,000 single stars and 12,000 binaries is evolved from zero-age and takes full account of cluster dynamics as well as stellar and binary evolution. At an age of 4 Gyr the model cluster matches the mass and structure of M 67 as constrained by observations. We discuss the role of the primordial binary population and the cluster environment in shaping the nature of the stellar populations of M 67, with a focus on X-ray binaries and blue stragglers.
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Vermeulen, R. C., R. T. Schilizzi, V. Icke, I. Fejes, and R. E. Spencer. "Evolving radio structure of the binary star SS433 at a resolution of 15 marc s." Nature 328, no. 6128 (1987): 309–13. http://dx.doi.org/10.1038/328309a0.
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Marchenko, Sergey V., Anthony F. J. Moffat, and Yves Grosdidier. "Dust-formation episode of the long-period WC+O binary WR 137: direct imaging with HST-NICMOS2." Symposium - International Astronomical Union 193 (1999): 368–69. http://dx.doi.org/10.1017/s0074180900205779.
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We have resolved, for the first time in any WR+OB system, IR-emitting dust in the close environment of the long-period binary WR 137. The dust emission occurs in a few clumps within about 0″.5 of the star, as well as in a jet-like structure with total extension of about 0″.25.
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Zhekov, Svetozar A., A. V. Myasnikov, and E. V. Barsky. "Colliding stellar winds: magnetic field structure in the interaction region." Symposium - International Astronomical Union 193 (1999): 400–401. http://dx.doi.org/10.1017/s0074180900205937.
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The geometry structure of the magnetic field in colliding stellar winds is studied. It is shown that the magnetic field influence in the interaction region depends mainly on the ratio of the wind ram pressures of the components, the ratio of the stellar linear rotational velocity to the wind velocity of the magnetized star, and the stellar separation. For the radiative colliding winds the magnetic field influence increases with the importance of the radiative losses. An asymmetric magnetic field structure appears for a given set of binary parameters and the interaction region might be an asymmetric source of non-thermal radio emission.
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Saleem, M. "Prospects of joint detections of neutron star mergers and short GRBs with Gaussian structured jets." Monthly Notices of the Royal Astronomical Society 493, no. 2 (2020): 1633–39. http://dx.doi.org/10.1093/mnras/staa303.
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ABSTRACT GW170817 was the first ever joint detection of gravitational waves (GW) from a binary neutron star (BNS) merger with the detections of short γ-ray burst (SGRB) counterparts. Analysis of the multiband afterglow observations of over more than a year revealed that the outflow from the merger end product was consistent with structured relativistic jet models with the core of the jet narrowly collimated to half-opening angles ∼5○. In this work, assuming that all the BNS mergers produce Gaussian structured jets with properties as inferred for GW170817, we explore the prospects of joint detections of BNS mergers and prompt γ-ray emission, expected during the current and upcoming upgrades of LIGO–Virgo–KAGRA detectors. We discuss three specific observational aspects: 1) the distribution of detected binary inclination angles, 2) the distance reach, and 3) the detection rates. Unlike GW-only detections, the joint detections are greatly restricted at large inclination angles, due to the structure of the jets. We find that at lower inclination angles (say below 20○), the distance reach as well as the detection rates of the joint detections are limited by GW detectability while at larger inclinations (say above 20○), they are limited by the γ-ray detectability.