Formation of magnetized spatial structures in the Beta Lyrae system III. Reflection of magnetically controlled matter in circumbinary structures in helium lines, in particular arising from metastable levels
aa r X i v : . [ a s t r o - ph . S R ] F e b Contrib. Astron. Obs. Skalnat´e Pleso , 7 – 40, (2021)https://doi.org/10.31577/caosp.2021.51.1.7 Formation of magnetized spatial structures inthe Beta Lyrae system
III. Reflection of magnetically controlled matter incircumbinary structures in helium lines, in particulararising from metastable levels
M.Yu. Skulskyy
Lviv Polytechnic National University, Department of Physics, 79013, Lviv,Ukraine (E-mail: [email protected])
Received: October 7, 2020; Accepted: November 3, 2020
Abstract.
Spatial gaseous structures in the Beta Lyrae system have beenstudied with the fact of change in the longitudinal component of the donor’smagnetic field during the orbital period in mind. The investigation was basedprimarily on the study of the dynamics of the circumstellar structures sur-rounding the binary system as a whole. The special emphasis was placed onthe study of complex helium lines, in particular those arising from metastablelevels. A number of different observable facts from the ultraviolet to the redspectral region were analyzed. The configuration of the donor magnetic fieldis a factor that not only enhances mass transfer and influences the forma-tion of spatial gas structures between stellar components but, to some extent,also affects the outflow of matter and the formation of external gas structuresaround this interacting binary system. Together with previous articles (Skul-skyy, 2020a,b), the pieces of evidence of this work, confirming the reflection ofmagnetically controlled matter in circumbinary structures, define the basis fora coherent picture of the mass exchange between components and outflows ofmatter outwards.
Key words: binaries: individual: Beta Lyrae – emission-line: magnetic field:mass-loss
1. Introduction
In previous papers, the focus was on the research of the relationship betweenthe structure of the donor magnetic field and its reflection in the characteristicphysical parameters of the visible and infrared Beta Lyrae spectra (Skulskyy,2020a,b). Taking into account the spatial configuration of the donor magneticfield, the emphasis was put on certain facts of its reflection in the moving mag-netized accretions structures between the stellar components of this binary sys-tem. The data of absolute spectrophotometry and spectral analysis, changesalong with the orbital phases of the radial velocities and intensities of complex
M.Yu. Skulskyy emission-absorption lines were examined, primarily based on the own spectraland spectrophotometric observations in the visual range spectrum. This was dueto a series of conscious and consistent spectral observations and relevant studiesconducted mainly in 1980-1995, after the discovery of the donor magnetic field.Such a method of approach has already made it possible to make certain gener-alizations and reflect moving magnetized structures as the original phenomenonof mass transfer, which is inherent to this binary system.It is clear that by the time when nothing was known about the donor’smagnetic field and its possible effect on the physical conditions in the near andfar gas structures of this binary system, a number of significant scientific studieshad been completed. Some physical characteristics and certain parameters ofradiating gas structures near both stellar components or in the common shellwere often described by the known paradigms, which were later rejected ormodified. This is especially true of researchers who have studied the spectrallines of the shell and the characteristics of the spectrum in the far ultravioletregion. A large number of scientific materials are available for their coverage andfurther rethinking. In this article, special attention is paid to the scientific worksin order to investigate the influence of the magnetic field on the dynamics ofthe circumstellar structure surrounding this binary system as a whole. Clearly,to create a coherent picture, such studies should be conducted in comparisonwith the already obtained results of the investigation of the magnetized gasstructures both near the donor and the gainer and between them.The previous researches of Skulskyy (2020a,b) demonstrate an efficient col-lision of magnetized plasma in the phases of observation of magnetic poles onthe donor surface. These shock collisions with the accretion disk in the phasesof the secondary quadrature, in which the high-temperature environment andthe system of formed accretion flows are observed, are especially noted. Thereare obvious correlations between the phase variability of the donor magneticfield and the corresponding variability of dynamic and energy characteristics ofdifferent complex lines, but above all the strongest emission lines H α and He I λ ormation of magnetized spatial structures in the Beta Lyrae system
2. Magnetic field and gaseous structures surrounding thebinary system
The gas shell surrounding the Beta Lyrae system was discovered long ago and itsstructure has always been studied on the basis of helium lines originating frommetastable levels. First of all, it concerned the strongest emission-absorptionline of the He I λ λ λ λλ S. This levelis highly populated with electrons and the effects of collision are crucial for themanifestation of these lines in the spectrum. Indeed, absorption componentsof these triplet lines of helium are well visible in the diluted shell structurearound this binary system. At the same time, these helium lines have a verystrong emission component in their contours, in many respects similar to thosein lines H α and He I λ λλ M.Yu. Skulskyy
Based on the concept of the existing configuration of the donor’s magnetic field,the careful work of Sahade et al. (1959) can be considered as one of the mostconsistent and informative studies of the He I λ λλ λ α and He I λ λ α and He I λ λ λ λ α andHe I λ α and He I λ ormation of magnetized spatial structures in the Beta Lyrae system Figure 1.
Radial velocities from the shell (triplet) line at He I λ (2020b). These maxima at the 0.35 P and 0.85 P phases match clearly the phasesof the two maxima on the curve of the effective magnetic field strength of thedonor (see also Fig. 1 in Skulskyy, 2020b). Being synchronized in orbital phases,all these emission components have clear similarities, their physical nature andspatial interconnection seem indisputable. It can be assumed that the formationof red peaks in these lines, including such for the line He I λ α and He I λ λ M.Yu. Skulskyy
Figure 2.
Radial velocities from the emission ”peak” at He I λ Sahade et al. (1959), is -15.2 km/s. The γ - velocity determined in Table 9, forthe set of orbital elements of Beta Lyrae computed on the basis of all 192 spec-tral plates in the summer of 1955, is -16.0 km/s. The set of orbital elements,calculated from observations taken between 0.85 P and 0.15 P phases, i.e., withthe data discarded during the main (or primary) eclipse, showed -15.0 km/sfor the -velocity. That is, both absorption components with radial velocities ofapproximately -170 and -130 km/s, should be considered as components withaverage velocities of about -155 and -115 km/s. Modern stellar masses of thisbinary system and the inclination of the orbit (see in Skulskyy, 2020a) allowaffirming that the parabolic velocity of the moving gas particles reaches a valueslightly smaller, but close to -115 km/s, which is sufficient to reach the Rochecavity with the Lagrange point L2. A simple calculation also shows (Burnashev& Skulskij, 1991) that the velocity of the particles, which is sufficient to reachthe Roche cavity with the Lagrange point L3, is near to -160 km/s. That is, theabsorption component with an average radial velocity of approximately -155km/s, or its possible greater values, may indicate a mass loss in a wider rangeof directions, in particular in the direction of the Lagrange points L4 and L5.Here it is important to emphasize that Sahade et al. (1959) themselves noted:“there are striking changes with phase and cycle in the spectrum” and “thegreat complexity of the spectrum of Beta Lyrae makes it impossible to give adescription which would do justice to the wealth of information contained inthe material”. Indeed, at some points, this spectral material is presented as ageneral description. Now it is possible to consider the data of the observationin the light of modern ideas and concepts, in a more detailed manner. The ormation of magnetized spatial structures in the Beta Lyrae system λ λ λ M.Yu. Skulskyy
Figure 3.
Radial velocities from the shell (singlet) lines at He I λ growth within 5 km/s, however, in phases (0.11-0.13) P on June 10, its averagethe velocity was -180 km/s (on the first 4 plates it was -175 km/s, on the next 4plates in phase near 0.12 P has reached the average velocity of -185 km/s, then itwas -181 km/s and -180 km/s, respectively). Confident achievement of the radialvelocity of -185 km (-170 km/s relative to the center of gravity) indicates that inthis direction, the velocity of the particles was sufficient for the free escaping ofthe matter from the binary system with the intersection here of the boundary ofthe Roche cavity with the Lagrange point L3. But in the phases (0.03-0.05) P onJuly 5 and (0.12-0.14) P on July 6 of the 7th cycle, the average radial velocitywas -171 km/s, which is much smaller than the velocity of -185 km/s in the0.12 P phase on June 10. Moreover, for example, in the phases (0.987-0.002) Pat the boundary of cycles 11 and 12, this absorption component of the He I λ λ λ ormation of magnetized spatial structures in the Beta Lyrae system λλ λ M.Yu. Skulskyy pressed sets of both absorption components of these lines. If on June 10 bothcomponents of these lines became clearly double at radial velocities of -148 km/sand -98 km/s, then after two orbital cycles on July 6 the first of the two absorp-tion components diminished its velocity to -105 km/s, i.e., slightly less than theparabolic velocity, but the second absorption component was absent. Moreover,if in the 5th cycle in June both components of these lines with velocities of-148 km/s and -98 km/s became visible only in the phases (0.11-0.13) P, thenin the 6th cycle similar radial velocities -155 km/s and -98 km/s of both thesecomponents were measured in phases (0.98-0.99) P on July 4 and close to suchvelocities -151 km/s and -98 km/s on July 5 (in the 7th cycle) in phases (0.04-0.06) P (the next night on July 6, in phases (0.11-0.14) P the first absorptioncomponent had the radial velocity only -105 km/s, and the second absorptioncomponent unexpectedly disappeared and was invisible on the following nightsof this 7th cycle). Hence, it should be noted that within the main eclipse theHe I λλ λ λλ γ andHe I λλ ormation of magnetized spatial structures in the Beta Lyrae system ◦ , and therefore,this magnetic pole on the surface of the donor in phase 0.855P is also above theplane of the orbit. This means that the ionized gas directed by the donor’smagnetic field moves in the direction of the dipole axis from the donor’s surfaceand, deviating along the magnetic field lines towards the accretion disk, can riseabove the front edge of the disk without much energy loss.The tables and graphs in Sahade et al. (1959) allow of stand out certainaspects related to the moving matter in the direction of the axis of the mag-8 M.Yu. Skulskyy netic field of the donor. It is reasonable to estimate first the behavior of radialvelocities of absorption components of the above lines in orbital phases near0.85 P, i.e. in the phases of direct visibility on the donor surface of the mag-netic pole facing the gainer. From Fig. 1 it is seen that in phases around 0.8 Pboth absorption components in the He I λ λλ λ λ λ λ α and He I λλ ± ormation of magnetized spatial structures in the Beta Lyrae system λλ λ α and He I λλ As it was previously pointed out, the issues of the dynamics of circumstel-lar gaseous structures using lines He I λλ λλ λ λλ γ = -18 km/s according to measurementsof the radial velocities of the sharp interstellar line Ca II λ M.Yu. Skulskyy
Figure 4.
Variations in the radial velocities curve of the He I λλ surements of the Zeeman splitting at Si II λλ ±
200 G, but as it can beseen from Figures 5 and 6 of Skulskyy (2020a), rapid changes in the magneticfield curve are clearly visible only in the phases near the poles of the magneticfield. In both cases, the polarity of the magnetic field varies within 0.1 P in the0.355 P phase of the first quadrature and in the 0.855 P phase of the secondquadrature. The behavior of the photographic curve of the magnetic field is alsocharacterized by rapid changes in the magnetic field curve around the 0.855 Pphase (i.e. the phase of observation of the magnetic pole facing the gainer) andin the phases around the main eclipse.Note that the sharp peak of radial velocities with a rapid change in theirvalues is observed in Fig. 4 in the phase of about 0.67 P (one can assume thatthe opening gas flow is in collision with the accretion disk). Similarly formedtwo narrow peaks of radial velocities are observed in the same phases of themain eclipse, in which the radial velocities of the opposite sign are observedin the satellite lines, characterizing the outer edges of the accretion disk. Itshould be concluded that due to different physical parameters at the edgesof the accretion disk a complex structure of plasma flows is formed, which mayparticipate primarily in mass transfer between components of the binary system,as well as in the outflow of matter outside it. In addition, note that the rapid ormation of magnetized spatial structures in the Beta Lyrae system Figure 5.
The radial velocity of the He I λ changes of radial velocities near the main eclipse in the He I λλ λλ λ γ = -18 km/s, which is determinedwithin 2 km/s on the spectrographs of the Crimean, Ondrejov and Peak TerskolObservatories). The range of measurements of radial velocities according to our2 M.Yu. Skulskyy
Crimean observations in 1966-68 and 1972, our more recent observations in2008-2010 at Peak Terskol, as well as observations in 1991 in Ondrejov, lies ina range from -118 km/s to -142 km/s at the average radial velocity near -130km/s. There are no such sharp jumps in radial velocities inherent in the curveof radial velocities of the He I λλ λ λ λ λ In this study, it is necessary to consider the radial velocity curve of the He I λ ormation of magnetized spatial structures in the Beta Lyrae system λ λ λ λ λ λλ λλ λλ λ λ λ λ M.Yu. Skulskyy −120−100−80−60−40−140−120−100−80−60−40−20 0.0 0.5 1.0 1.5Phase−130−120−110−100−90−80V r Figure 6.
The radial velocities (plotted according to data of Flora & Hack (1975)) forcertain shell lines in the Beta Lyrae spectrum. At the top there are lines He I λ λ λ λ λ λ λ matter outflows have velocity much smaller than the parabolic velocity.Since the observer in phases (0.75 - 0.85) P looks perpendicularly to theline of centers of stellar components and along the axis of the dipole magneticfield of the donor (the motion of matter to the observer), the most adequateexplanation of this picture can be considered as the consequences of loss ofmatter directly from the donor surface near its magnetic pole in phase 0.855 Pand its subsequent transfer to the gainer. It should be noted that the He I λ ormation of magnetized spatial structures in the Beta Lyrae system ◦ (Skulskij, 1985). Indeed, the hot surface on the donor continuesto be observed almost to the 0.50P phase, demonstrating during the orbitalphases (0.38-0.49) P the clear variability of the absolute radiation flux in the H α emission line and the rapid variability of the spectrum in the H α emission region(see also Alexeev & Skulskij, 1989). This may be a reflection of the collisionsof the hot plasma with the donor surface, directed (to the observer with theradial velocity close to the first parabolic velocity) along the lines of force of themagnetic field. Note that in these phases, there is a bifurcation of the absorptioncomponent so that both shallow absorption components are superimposed on thestrong emission component of lines H α , He I λ λ λλ λλ M.Yu. Skulskyy the donor (see Fig. 1 in Skulskyy (2020b)). The presence of narrow interstellarcomponents of the Na I lines allowed us to check the tabular data and to clarifythe radial velocities of the shell components of these sodium lines directly fromFigs. 7a and 7b of Flora & Hack (1975). Fig. 6 shows that the observation inphases (0.8 - 0.9) P is especially interesting. Since the interstellar componentsin Na I λλ λλ λλ λλ λ λ λ λλ ormation of magnetized spatial structures in the Beta Lyrae system λ λλ α along thesurface of the donor. In particular, Fig. 15 of Flora & Hack (1975) shows that theequivalent width of the absorption, measured with respect to the total area ofthe emission in the H α line, is halved in the phase direction (0.1 - 0.6) P, and thetotal equivalent width of emission plus the absorption of the H α line shows twodeep minima in the phases (0.25-0.45) P and about 0.855 P, i.e. near the phasesof visibility of both magnetic poles on the donor surface. Of course, to someextent, this is the result of reflecting the characteristics of the donor that fillsits Roche cavity: the loss of matter along the axis of the magnetic field at its poleand the loss of matter at the Lagrange point L1, amplified by the massive gainerand deflected by Coriolis forces to the 0.1 P phase, are significantly different. Atthe same time, the variable motions of the plasma are reflected more clearlyin the phases around 0.855 P of the visibility of the magnetic pole, facing thegainer, in accordance with the changes in the polarity of the magnetic field inthe observations of Skulskij & Plachinda (1993). λ If the structure and behavior of the He I λ λ M.Yu. Skulskyy −750 −500 −250 0 250 500 750 1000 km/s
I/I c Figure 7.
Contours of the He I λ λ λ λ ormation of magnetized spatial structures in the Beta Lyrae system I V I R b68101214F⋅10 c0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4Phase−150−140−130−120−110V r d Figure 8.
Changes with the phase of the orbital period of the ratio of intensities ofemission components, radiation flux, and radial velocities of the absorption componentin the He I λ During 26 nights of this season, 59 spectrograms with a dispersion of 48 ˚A/mmwere obtained, which allowed measuring radial velocities with an error of 10km/s. As it can be seen from Fig. 7, which is a copy of Fig. 1 from Girnyak et al.(1978), this line in the Beta Lyrae spectrum represents the strong emission thatis several times higher with respect to the continuum than such emission in theHe I λ λ M.Yu. Skulskyy
Girnyak et al. (1978) proposed processed physical parameters of the He I λ λ − A − km/s, multiplied by 10 (contours in the He I λ I v /I r = f ( P ), which we built here on the basisof the tabular data. In Fig. 8, bottom, it is seen that the V r = f ( P ) curve ofthe absorption component, which separates these emission components, remainsapproximately the same in the orbital phases at an average value of about -130km/s (taking into account the radial velocity of -18 km/s for the center of gravityof this binary system). The largest scattering of data and rapid changes in radialvelocities are observed in the range of phases (0.7-0.9) P, and a particularly sharpvelocity change is shown in the phases around 0.855 P of the visibility of themagnetic pole, facing the gainer. Similar behavior in these phases there is inchanges of contours in the He I λ I v /I r = f ( P ) (theupper part of Fig. 8), characterizing the expected variability of shell structuresin this binary system. The dependence of I v /I r = f ( P ) showed a clear decreasein the I v /I r ratio after the 0.855 P phase (of the direct visibility of the magneticfield pole on the donor surface) to the minimum in the main eclipse phase andits rapid rise to the phase 0.15 P, when the main flow of matter from the donorto the gainer, deflected by the Coriolis forces, begins after the main eclipse. Itshould be noted that these observations do not provide enough data for moredefinite conclusions in the phases (0.95-0.05) P of the main eclipse.Nevertheless, the radial velocity curve of the He I λ λ λ ormation of magnetized spatial structures in the Beta Lyrae system r I V I R Figure 9.
The same as in Fig. 8 for the He I λ not explicitly distort the position of the absorption component, and the radialvelocity of the emission center as a whole turned out to be close to the orbitalvelocity of the gainer, based on the previously established mass ratio of thestellar components (Skulskij, 1975). However, Figs. 1 and 6, which respectivelyrelate to the studies of Sahade et al. (1959) and Flora & Hack (1975), showedthat the behavior of the He I λ λ λ λ M.Yu. Skulskyy close seasons and the dynamic behavior of the shell lines He I λ λ λ λ λ λ λ λλ λλ λ λ λ λ λλ λ ormation of magnetized spatial structures in the Beta Lyrae system
33a certain configuration of the donor’s magnetic field. The study of the spectralcharacteristics of the He I λ
3. Conclusions and discussion
The study of shell structures in the Beta Lyrae system seemed natural on thebasis of previous studies by Skulskyy (2020a,b), which involved a continuousinteraction of the outer shell with a complex system of plasma flows betweenthe donor and the gainer. It is clear that the spectral lines formed in externalstructures, in particular the helium lines arising from metastable levels, werestudied. Scientific articles were used for the study, which, on the basis of quali-tative observations, covered the orbital period well. There are few similar works,in particular Sahade et al. (1959); Flora & Hack (1975); Girnyak et al. (1978),which are half a century old. It is to some extent well that the authors of theseworks presented their results without the influence of modern interpretations,say, without information about the magnetic field of the donor or ideas aboutbipolar jet structures associated with the accretion disk. However, these arti-cles have a lot of important spectral material in the form of published tablesand graphs. As a whole, this material, together with data from more recentpublications of Harmanec & Scholz (1993) and Skulsky & Kos (2011), havenot been analyzed in more detail. Here an attempt was made to overcome thisshortcoming.All researched articles are distinctive. They differ significantly in the en-ergy and dynamic parameters of the moving plasma in the medium near eachcomponent and between stellar components of the binary system. First, signif-icant long-term differences were found within half a century in the movementsof matter to the gainer and in external structures. Second, there are significantdifferences in the physical parameters of this plasma within one observation sea-son and their variations from cycle to cycle (especially in Sahade et al. (1959)).It was established (see Fig. 1) only in Sahade et al. (1959) that: “He I λ λ λ λλ M.Yu. Skulskyy (2011). It seems that all these differences are not periodically ordered. It shouldbe emphasized that all researched articles show the averaged radial velocity inthe He I λλ λλ λ λλ λ λλ λ λ λλ ormation of magnetized spatial structures in the Beta Lyrae system λλ λλ λ λ M.Yu. Skulskyy passage of the donor in front of the accretion disk. In phases (0.38-0.50) P theright part of the disk is observed (its left part being closed by the donor); inphases (0.45-0.55) P the central parts of the disk, closed by the donor, pass infront of the observer; in phases (0.5-0.6) P dominates in these lines the left part ofthe accretion disk (the donor obscures the right part of the disk). Approximatelyat 0.62 P, this effect disappears (further there are opened phases of the collisionof the main flow into the accretion disk and the region of the magnetic fieldpole on the donor surface). In particular, this effect is well observed in phases(0.38-0.62) P in the behavior of the gainer radial velocities of the Si II λλ λ λλ λ λλ λ λ I v /I r = f ( P ), i.e., ormation of magnetized spatial structures in the Beta Lyrae system λ α line (see Figures 5in Skulskyy (2020b). The maxima at the 0.355 P and 0.855 P phases coincidewith the phases of the two maxima on the curve of the effective magnetic fieldstrength of the donor (see Figure 1 in Skulskyy (2020b) or Figure 2 in Burnashev& Skulskij (1991)). Moreover, the radial velocity curve for the Gaussian centerof emission in H α , as well as for such centers on radial velocity curves of theHe I λλ λλ V r -curve of thecenter of the He I λ λλ ◦ relative to the orbital plane of the binary8 M.Yu. Skulskyy system (Skulskij, 1985). The center of the donor magnetic dipole is displaced by0.08 of the distance between the centers of gravity of both components towardthe gainer’s center. It is also clear that the magnetic pole, located on the surfaceof the donor and observed in phases of about 0.855 P, is more effective in termsof the amount of transferred matter to the gainer, which is confirmed by allstudies. The ionized gas, directed by the magnetic field of the donor in thedirection of its dipole axis from the surface of the donor, is deflected along thelines of the magnetic field primarily to the accretion disk. However, a certainamount of charged particles will move along the lines of force of the magneticfield in the direction to the second pole of the magnetic field on the surface of thedonor, heating its surface. And, if in the first quadrature in the phases around0.355 P the magnetic pole on the surface of the donor is located above the planeof the orbit, then in the phases around 0.855 P the magnetic pole on the surfaceof the donor is below the plane of the orbit, or vice versa. The detection of thesepoles also depends on the inclination of the plane of the orbit. Not everything isclear in this part because the inclination of the orbit in current research is takenfrom i = 81 ◦ in Mennickent & Djuraˇsevi´c (2013) to i = 93.5 ◦ in Mourard et al.(2018). This is close to the binary orbital inclination i = 90 ◦ , and regardless ofwhether the pole of the magnetic field is in the upper or lower hemisphere onthe donor surface, the observer, due to the projection of the rounded shape ofthe surface on the line of sight, must register certain deviations of the surfaceheating maximum from the 0.355 P phase. This is confirmed by the absolutespectrophotometry of Burnashev & Skulskij (1991) of 1974-1985. They showedthat the observer starts to register the excess radiation (a hot spot on the donorsurface) only from the 0.355 P phase directed along the axis of the magneticfield (see Figure 1 in Skulskyy (2020b)). The excess of this radiation disappearsnear the 0.50 P phase, demonstrating during the orbital phases (0.37-0.49) P therapid variability of the absolute radiation flux in the H α emission line and thecontinuum around this line (see Skulskyy, 2020b; Alexeev & Skulskij, 1989).The maximum of the excess of this radiation is really shifted from the 0.355 Pphase and corresponds to the phases (0.43-0.47) P. Thus, in these phases, somesurface heating on the donor surface may be formed due to nonstationary shockcollisions of ionized gas, directed along the magnetic field lines to the magneticfield pole, the location of which is given by the spatial configuration of themagnetic field dipole. The phase range (0.43-0.47) P corresponds to the knownminimum on the polarization curves for Beta Lyrae studied by Appenzeller& Hiltner (1967) and Lomax et al. (2012), which is interpreted as formed bycollisions of gas flows with the accretion disk during the scattering of radiationby free electrons. This encourages the research of the reflection of the spatialconfiguration of the donor’s magnetic field in the polarization observations. Acknowledgements.
The author is thankful to V.I. Kudak for consultations. ormation of magnetized spatial structures in the Beta Lyrae system References
Ak, H., Chadima, P., Harmanec, P., et al., New findings supporting the presence of athick disc and bipolar jets in the β Lyrae system. 2007,
Astronomy and Astrophysics , , 233, DOI: 10.1051/0004-6361:20065536Alduseva, V. Y. & Esipov, V. F., The line He I λ β Lyr shell. 1969,
Astro-nomicheskii Zhurnal , , 113Alexeev, G. N. & Skulskij, M. Y., Rapid variability of the spectrum of β Lyrae in the H α region. 1989, Bull. Spec. Astroph. Obs. , , 21Appenzeller, I. & Hiltner, W. A., True polarization curves for Beta Lyrae. 1967, As-trophysical Journal , , 353, DOI: 10.1086/149258Bisikalo, D. V., Harmanec, P., Boyarchuk, A. A., Kuznetsov, O. A., & Hadrava, P.,Circumstellar structures in the eclipsing binary β Lyr A. Gasdynamical modellingconfronted with observations. 2000,
Astronomy and Astrophysics , , 1009Burnashev, V. I. & Skulskij, M. Y., Absolute spectrophotometry of β Lyr. 1978,
Izv.Krymskoj Astrofiz. Obs. , , 64Burnashev, V. I. & Skulskij, M. Y., H α photometry and magnetic field of β lyrae.1991, Izv. Krymskoj Astrofiz. Obs. , , 108Flora, U. & Hack, M., Spectrographic observations of β Lyr during the internationalcampaign of 1971. 1975,
Astronomy and Astrophysics, Supplement , , 57Girnyak, M. B., Skulskij, M. Y., Shanin, G. I., & Shcherbakov, A. G., The investiga-tion of the emission line of He I λ Izv.Krymskoj Astrofiz. Obs. , , 75Harmanec, P. & Scholz, G., Orbital elements of β Lyrae after the first 100 years ofinvestigation. 1993,
Astronomy and Astrophysics , , 131Hoffman, J. L., Nordsieck, K. H., & Fox, G. K., Spectropolarimetric evidence fora bipolar flow in Beta Lyrae. 1998, Astronomical Journal , , 1576, DOI:10.1086/300274Lomax, J. R., Hoffman, J. L., Elias, Nicholas M., I., Bastien, F. A., & Holenstein,B. D., Geometrical constraints on the hot spot in Beta Lyrae. 2012, AstrophysicalJournal , , 59, DOI: 10.1088/0004-637X/750/1/59Mennickent, R. E. & Djuraˇsevi´c, G., On the accretion disc and evolutionary stage of β Lyrae. 2013,
Monthly Notices of the RAS , , 799, DOI: 10.1093/mnras/stt515Morgan, T. H., Potter, A. E., & Kondo, Y., Complex infrared emission featuresin the spectrum of Beta Lyrae. 1974, Astrophysical Journal , , 349, DOI:10.1086/152883Mourard, D., Broˇz, M., Nemravov´a, J. A., et al., Physical properties of β Lyrae Aand its opaque accretion disk. 2018,
Astronomy and Astrophysics , , A112, DOI:10.1051/0004-6361/201832952Rucinski, S. M., Pigulski, A., Popowicz, A., et al., Light-curve instabilities of β Lyraeobserved by the BRITE satellites. 2018,
Astronomical Journal , , 12, DOI:10.3847/1538-3881/aac38b M.Yu. Skulskyy
Sahade, J., Huang, S. S., Struve, O., & Zebergs, V., The spectrum of Beta Lyrae. 1959,
Transactions of the American Philosophical Society , , 1Shore, S. N. & Brown, D. N., Magnetically controlled circumstellar matter in thehelium-strong stars. 1990, Astrophysical Journal , , 665, DOI: 10.1086/169520Skulskij, M. Y., Quantitative analysis of the spectrum of Beta Lyrae IV. Line identifi-cations for the faint component and the mass of both stars. 1975, AstronomicheskiiZhurnal , , 710Skulskij, M. Y., The magnetic field of the Beta-Lyrae system. 1985, Sov. Astron. Lett. , , 21Skulskij, M. Y., Study of β Lyrae CCD spectra. Absorbtion lines, orbital elements anddisk structure of the gainer. 1992,
Sov. Astron. Lett. , , 287Skulskij, M. Y., Spectra of β Lyr. Matter transfer and circumstellar structures inpresence of the donor’s magnetic field. 1993a,
Astron. Lett. , , 45Skulskij, M. Y., Study of β Lyrae spectra - the Si II λλ Astron. Lett. , , 19Skulskij, M. Y., The spectrum of β Lyrae: the SiII λλ Astron. Lett. , , 160Skulskij, M. Y. & Plachinda, S. I., A study of the magnetic field of the bright compo-nent of β Lyr in the SiII λλ Pisma Astron. Zh. , , 517Skulsky, M. Y. & Kos, E. S., On the dynamics of circumstellar gaseous structures andmagnetic field of β Lyrae. 2011, in
Magnetic Stars. Proceedings of the InternationalConference, held in the Special Astrophysical Observatory of the Russian AS, August27- September 1, 2010 , ed. I. Romanyuk & D. Kudryavtsev, 259–263Skulskyy, M. Y., Formation of magnetized spatial structures in the Beta Lyrae system.I. Observation as a research background of this phenomenon. 2020a,
Contrib. Astron.Obs. Skalnat´e Pleso , , 681, DOI: 10.31577/caosp.2020.50.3.681Skulskyy, M. Y., Formation of magnetized spatial structures in the Beta Lyrae sys-tem. II. Observation as a research background of this phenomenon. 2020b, Contrib.Astron. Obs. Skalnat´e Pleso , , 717, DOI: 10.31577/caosp.2020.50.4.717Struve, O., The Spectrum of β Lyrae. 1941,
Astrophysical Journal , , 104, DOI:10.1086/144249Umana, G., Maxted, P. F. L., Trigilio, C., et al., Resolving the radio nebula aroundBeta Lyrae. 2000, Astronomy and Astrophysics , , 229Zeilik, M., Heckert, P., Henson, G., & Smith, P., Infrared photometry of Beta Lyrae:1977-1982. 1982, Astronomical Journal ,87