X-Ray Sources in Close Binary Systems

1974 ◽  
pp. 89-107 ◽  
Author(s):  
M. J. Rees
Keyword(s):  
Binary Systems ◽  
Close Binary ◽  
X Ray ◽  
Close Binary Systems

scholarly journals X-Ray Sources in Close Binary Systems

1974 ◽  
Vol 3 ◽  
pp. 89-107
Author(s):  
M. J. Rees
Keyword(s):  
Binary Systems ◽  
Close Binary ◽  
Rapid Variability ◽  
X Ray ◽  
Close Binary Systems ◽  
General Order ◽  
Typical Distances ◽  
Astronomical Research ◽  
Orbital Periods ◽  
Galactic Sources

The discovery by Giacconi and his colleagues of variable X-ray sources in close binary systems certainly ranks as one of the highlights of astronomical research during the last 3 years. These remarkable objects have already been extensively studied, by optical and radio observations as well as in the X-ray band; and they seem likely to prove as significant and far-reaching in their implications as pulsars.The ‘Third Uhuru Catalogue’ (Giacconi et al., 1973a) contains about 160 sources, of which about 100 lie in our Galaxy. Their distribution over the sky (together with other arguments) suggests that these sources have luminosities of the general order 1036–1038 erg s−1, and that their typical distances are ˜ 10kpc. These galactic sources generally display rapid variability. Little else is known about most of them, but they are probably of the same general class as systems such as Her X1, Cen X3, Cyg X1 and Cyg X3. These sources have been investigated in detail, and in all cases one infers a system where the X-ray source is orbiting around a relatively ordinary star. Six sources have been optically identified, and there are some others whose binary nature is established by the occurrence of an X-ray eclipse. Orbital periods range from 4.8 h (Cyg X3) up to ˜ 10 days.

scholarly journals Radio Aspects of Stellar Activity in Close Binaries

1980 ◽  
Vol 5 ◽  
pp. 857-857 ◽  
Author(s):  
R. M. Hjellming
Keyword(s):  
Circular Polarization ◽  
Binary Systems ◽  
Close Binary ◽  
Close Binaries ◽  
Radiation Mechanisms ◽  
Dynamo Action ◽  
Stellar Activity ◽  
X Ray ◽  
Close Binary Systems ◽  
Decay Times

Excluding single stars, star systems with very strong X-ray sources, thermally radiating winds and circumstellar envelopes, marginal detections, and binary systems that are far from “normal”, there are about 21 close binary systems that show clear signs of stellar activity in the form of variable radio emission. Sixteen of these are RS CVn binaries. Typical events are smoothly varying with time scales of from a few hours to a few days. In the RS CVn binaries UX Ari and V711 Tau variable circular polarization is sometimes observed, with occasional appearence of components with only one frequency and one circular polarization, part of which shows “oscillations” with “periods” of about 4 minutes. Different stars and different events typically have inferred electron energies of about 5 MeV and inferred magnetic fields of 1 - 30 Gauss. The radiation mechanisms are usually assumed to be synchrotron or gyro-synchrotron; however, radiation from plasma processes cannot be ruled out in some cases, and it will be very important to establish or rule out this possibility. Most radio binary events show clear signs of self-absorption, so the variations appear most strongly at the higher frequencies. Typical rise times of events are about 30% of decay times. Maximum radio luminosities range from 1013 to a few times 1017 ergs s-1 Hz-1. Most radio flares are mainly at cm-wavelenghts and have observable and inferred energies 104 - 106 times those for the largest solar events, a scaling which is similar to that for X-ray emission measures of these stars when compared to solar coronal loop emission measures. Most importantly, VLBI measurements of Algol indicate that the sizes of the radio emitting regions for very strong events are of the order of 2 - 3 stellar radii. Single stars appear to be active at radio wavelengths much less commonly than close binary systems. In many cases this may be due to the way dynamo action and convection near the surface are affected by increased rotation forced by the synchronization induced by the binary system.

scholarly journals Polarimetry of Close Binary Systems; Observations and Interpretations

1980 ◽  
Vol 88 ◽  
pp. 65-70
Author(s):  
Ian S. McLean
Keyword(s):  
Binary Systems ◽  
Stokes Parameters ◽  
Close Binary ◽  
Stellar Winds ◽  
Line Profiles ◽  
Orbital Inclination ◽  
X Ray ◽  
Close Binary Systems ◽  
A New Technique ◽  
X Ray Binaries

Polarization caused by scattering of starlight on gaseous extrastellar material in close binary systems is reviewed. A simple physical derivation is given to illustrate how in principle, variations synchronous with the orbital period of the Stokes parameters of the linear polarization can yield the orbital inclination and other parameters. High resolution multichannel spectropolarimetry across the emission line profiles of binaries is discussed as a new technique in studying the physics and kinematics of gaseous streams and stellar winds. The methods have application to a range of binary objects including systems like Algol and Beta Lyrae, X-ray binaries, Of and Wolf-Rayet binaries, VV Cephei stars and symbiotic stars. Some new observational results are presented.

scholarly journals Radio Emission from Close Binary Systems and Novae

1977 ◽  
Vol 42 ◽  
pp. 279-291
Author(s):  
R.M. Hjellming
Keyword(s):  
Magnetic Fields ◽  
Radio Emission ◽  
Binary Systems ◽  
Close Binary ◽  
X Ray ◽  
Close Binary Systems ◽  
Nova Shells ◽  
The Subject ◽  
Continuum Radio ◽  
Relativistic Particles

This review of the radio emission properties of close binary systems and novae will be partly concerned with surveying the star systems that exhibit continuum radio emission, and partly concerned with discussing the implications of the observed radio emission. The phenomena we will encounter will range from purely thermal continuum radio emission for the case of ionized nova shells to strong, non-thermal continuum radio emission produced by relativistic particles in both ‘normal’ and X-ray emitting close binary systems. In keeping with the subject of this symposium, let me emphasize that all regions involving radio emission are from the portions of the stellar environment where Ne ≤ 1010cm-3, generally rather high in the stellar or systemic atmosphere; however, events more closely associated with the stars themselves are the root causes of the phenomena, supplying energy, mass, magnetic fields, and relativistic particles.

scholarly journals Collapse of White Dwarfs in Close Binary Systems

1979 ◽  
Vol 53 ◽  
pp. 52-55
Author(s):  
R. Canal ◽  
J. Isern
Keyword(s):  
Neutron Star ◽  
White Dwarf ◽  
Binary Systems ◽  
Critical Density ◽  
Close Binary ◽  
Type I ◽  
X Ray ◽  
Close Binary Systems ◽  
Chandrasekhar Limit ◽  
Thermonuclear Runaway

The presence of neutron stars in close binary systems, shown by the pulsating X-ray sources, poses the problem of their origin. In the case of the low-mass (M1 + M2 ≤ 5 M⊙) X-ray binaries, the neutron star might have originated from a massive white dwarf, driven over the Chandrasekhar limit by mass transfer (Schatzman 1974). A similar scenario had been put forward by Whelan and Iben (1973) for type I supernovae. To solve the problem of the very low eccentricities observed for the orbits, and to facilitate keeping the system bound after neutron star formation, Canal and Schatzman (1976) suggested a non explosive collapse of the white dwarf to a neutron star. The occurence of this kind of collapse depended on the possibility of avoiding thermonuclear ignition by means of neutronization. Since there is a density interval where the electron captures on carbon go faster than the pycnonuclear reactions, just above the critical density for the beginning of the collapse, there seemed also to be a chance of escape from thermonuclear runaway. A closer examination of this picture leads, however, to significant changes.

scholarly journals Are there prominences around binary systems?

1996 ◽  
Vol 176 ◽  
pp. 461-468
Author(s):  
R. D. Jeffries
Keyword(s):  
Coronal Loop ◽  
Binary Systems ◽  
Light Curves ◽  
Close Binary ◽  
Gravitational Attraction ◽  
X Ray ◽  
Circumstellar Material ◽  
Close Binary Systems ◽  
Thermal Perturbations ◽  
Coronal Structures

I examine the possibility that large, cool prominences can be formed in close binary systems, when coronal structures grow beyond the point where centrifugal force balances gravitational attraction. X-ray light curves of the eclipsing binary XY UMa indicate that an extended corona is probably present and this is likely to reach heights > 1.5 R⊙, where centrifugal compression may render plasma in the coronal loop apexes unstable to thermal perturbations. Cool condensations could form, explaining features such as the dips in the X-ray light curves of V471 Tau, and the circumstellar material deduced to be present in several close binary systems.

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