The origin of the radio emission from <i>β</i> Lyrae

Umana, G.; Leone, F.; Trigilio, C.

doi:10.1051/0004-6361:20020878

Cited by 9 publications

(9 citation statements)

References 26 publications

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“…They proposed a detailed model in which the UV continuum originates from the accretion disk, and is scattered by the bipolar outflow, the Hα and Hβ being emitted mainly in the polar flow, despite a significant contribution from the equatorial environment and the hot spot, and the HeI 6678 Å originates from the mass flow between the gainer and the donor. The material possibly connected with the bipolar flow is also inferred by the resolved radio nebula observed around β Lyr (Umana et al 2000(Umana et al , 2002). An extensive spectroscopic and photometric study (Ak et al 2007) has given new support to the presence of a thick disk and bipolar jets in this system.…”

Section: Introductionmentioning

confidence: 79%

A large Hαline forming region for the massive interacting binaries β Lyrae and υ Sagitarii

Bonneau¹,

Chesneau²,

Mourard³

et al. 2011

A&A

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Aims. This study aims at constraining the properties of two interacting binary systems by measuring their continuum-forming region in the visible and the forming regions of some emission lines, in particular Hα, using optical interferometry. Methods. We have obtained visible medium (R ∼ 1000) spectral resolution interferometric observations of β Lyr and of υ Sgr using the VEGA instrument of the CHARA array. For both systems, visible continuum (520/640 nm) visibilities were estimated and differential interferometry data were obtained in the Hα emission line at several epochs of their orbital period. For β Lyr, dispersed visibilities and phases were also obtained in the Hβ and the HeI 6678 Å lines. Results. As expected, for baselines shorter than 60 m, the system of β Lyr is unresolved in the visible continuum, but the source associated with the Hα, the Hβ and the HeI 6678 Å lines appears to be well resolved at any orbital phase. The differential visibilities through these lines are lower during eclipses, indicating that significant emission originates close to the stars. The Hα line forming region appears to be made up of a compact source located near the orbital plane (possibly linked with the "hot point") and an extended source (i.e. ≥2 mas, i.e. 125 R ) out of the orbital plane (possibly associated to the "jet-like feature"). The υ Sgr continuum visibilities are at a similar level for short (20-25 m) and long (90-110 m) baselines. This is interpreted as the presence of an extended structure surrounding a compact bright source. No binary signal was detected, excluding a flux ratio between the stellar components of the system larger than 0.1 from 500 to 700 nm. The radius of the brightest star is estimated to be 0.33 ± 0.16 mas, i.e. 21 ± 10 R using the latest Hipparcos distance. By contrast, the Hα line forming region is very extended (i.e. ≥6 mas, i.e. 400 R ) and found to be off-center from the brightest star, following the orbital motion of the hidden companion. Conclusions. In both cases, the extension of the Hα line forming region is much larger than the size of the system, which is indicative of a non-conservative evolution. Although a large circumbinary disk surrounds the evolved system υ Sgr, storing a considerable part of the lost material, a substantial part of the Hα, Hβ, and the HeI 6678 Å line emission derives from regions perpendicular to the orbital plane of β Lyr.

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Section: Introductionmentioning

confidence: 79%

A large Hαline forming region for the massive interacting binaries β Lyrae and υ Sagitarii

Bonneau¹,

Chesneau²,

Mourard³

et al. 2011

A&A

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“…A binary class in this spectral range that is thought to be intermediate in evolution between the young semi-detached B-type β Lyr system that shows radio evidence for large systemic wind mass loss (Umana et al 2000), and evolved normal Algol binaries with non-thermal coronal emission is defined by the rather inhomogeneous sample of Serpentid stars or "Peculiar Emission Line Algols" (PELAs). These typically consist of an A−B type primary and a F−K type companion with strong mass transfer into a geometrically thick accretion disk around the early-type star, and a common, thin envelope.…”

Section: Stars At the Interface Between Hot Winds And Coro-naementioning

confidence: 99%

Stellar Radio Astronomy: Probing Stellar Atmospheres from Protostars to Giants

Guêdel

2002

Annu. Rev. Astron. Astrophys.

338

350

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▪ Abstract Radio astronomy has provided evidence for the presence of ionized atmospheres around almost all classes of nondegenerate stars. Magnetically confined coronae dominate in the cool half of the Hertzsprung-Russell diagram. Their radio emission is predominantly of nonthermal origin and has been identified as gyrosynchrotron radiation from mildly relativistic electrons, apart from some coherent emission mechanisms. Ionized winds are found in hot stars and in red giants. They are detected through their thermal, optically thick radiation, but synchrotron emission has been found in many systems as well. The latter is emitted presumably by shock-accelerated electrons in weak magnetic fields in the outer wind regions. Radio emission is also frequently detected in pre–main sequence stars and protostars and has recently been discovered in brown dwarfs. This review summarizes the radio view of the atmospheres of nondegenerate stars, focusing on energy release physics in cool coronal stars, wind phenomenology in hot stars and cool giants, and emission observed from young and forming stars. Eines habe ich in einem langen Leben gelernt, nämlich, dass unsere ganze Wissenschaft, an den Dingen gemessen, von kindlicher Primitivität ist—und doch ist es das Köstlichste, was wir haben. One thing I have learned in a long life: that all our science, measured against reality, is primitive and childlike—and yet it is the most precious thing we have. A. Einstein 1951, in a letter to H. Mühsam, Einstein Archive 36-610

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“…They may be classified into four groups: bipolar jets (Umana et al 2000(Umana et al , 2002Ak et al 2007;Lomax & Hoffman 2011), enhanced winds (Chap. 4 of Maeder 2009;Tout & Pringle 1992), losses through the outer Lagrangian point L 3 (Sytov et al 2007), and "hotspot".…”

Section: Introductionmentioning

confidence: 99%

Non-conservative evolution in Algols: where is the matter?

Deschamps

Braun

Jorissen

et al. 2015

A&A

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Context. There is indirect evidence of non-conservative evolutions in Algols. However, the systemic mass-loss rate is poorly constrained by observations and generally set as a free parameter in binary-star evolution simulations. Moreover, systemic mass loss may lead to observational signatures that still need to be found. Aims. Within the "hotspot" ejection mechanism, some of the material that is initially transferred from the companion star via an accretion stream is expelled from the system due to the radiative energy released on the gainer's surface by the impacting material. The objective of this paper is to retrieve observable quantities from this process and to compare them with observations. Methods. We investigate the impact of the outflowing gas and the possible presence of dust grains on the spectral energy distribution (SED). We used the 1D plasma code Cloudy and compared the results with the 3D Monte-Carlo radiative transfer code Skirt for dusty simulations. The circumbinary mass-distribution and binary parameters were computed with state-of-the-art binary calculations done with the Binstar evolution code. Results. The outflowing material reduces the continuum flux level of the stellar SED in the optical and UV. Because of the timedependence of this effect, it may help to distinguish between different ejection mechanisms. If present, dust leads to observable infrared excesses, even with low dust-to-gas ratios, and traces the cold material at large distances from the star. By searching for this dust emission in the WISE catalogue, we found a small number of Algols showing infrared excesses, among which the two rather surprising objects SX Aur and CZ Vel. We find that some binary B[e] stars show the same strong Balmer continuum as we predict with our models. However, direct evidence of systemic mass loss is probably not observable in genuine Algols, since these systems no longer eject mass through the hotspot mechanism. Furthermore, owing to its high velocity, the outflowing material dissipates in a few hundred years. If hot enough, the hotspot may produce highly ionised species, such as Si iv, and observable characteristics that are typical of W Ser systems. Conclusions. If present, systemic mass loss leads to clear observational imprints. These signatures are not to be found in genuine Algols but in the closely related β Lyraes, W Serpentis stars, double periodic variables, symbiotic Algols, and binary B[e] stars. We emphasise the need for further observations of such objects where systemic mass loss is most likely to occur.

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The origin of the radio emission from β Lyrae

Cited by 9 publications

References 26 publications

A large Hαline forming region for the massive interacting binaries β Lyrae and υ Sagitarii

A large Hαline forming region for the massive interacting binaries β Lyrae and υ Sagitarii

Stellar Radio Astronomy: Probing Stellar Atmospheres from Protostars to Giants

Non-conservative evolution in Algols: where is the matter?

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