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Register a new userA cyclic bipolar wind in the interacting binary V393 Scorpii
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Added by
Ronald Mennickent Dr.
Publication date
2012
fields
Physics
and research's language is
English
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V393 Scorpii is a Double Periodic Variable characterized by a relatively stable non-orbital photometric cycle of 253 days. Mennickent et al. argue for the presence of a massive optically thick disc around the more massive B-type component and describe the evolutionary stage of the system. In this paper we analyze the behavior of the main spectroscopic optical lines during the long non-orbital photometric cycle. We study the radial velocity of the donor determining their orbital elements and find a small but significant orbital eccentricity (e = 0.04). The donor spectral features are modeled and removed from the spectrum at every observing epoch using the light-curve model given by Mennickent et al. We find that the line emission is larger during eclipses and mostly comes from a bipolar wind. We find that the long cycle is explained in terms of a modulation of the wind strength; the wind has a larger line and continuum emissivity on the high state. We report the discovery of highly variable chromospheric emission in the donor, as revealed by Doppler maps of the emission lines MgII 4481 and CI 6588. We discuss notable and some novel spectroscopic features like discrete absorption components, especially visible at blue-depressed OI 7773 absorption wings during the second half-cycle, Balmer double emission with V/R-curves showing Z-type and S-type excursions around secondary and main eclipse, respectively, and H_beta emission wings extending up to +- 2000 km/s. We discuss possible causes for these phenomena and for their modulations with the long cycle.
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We give a brief report on spectroscopic properties of V 393 Scorpii. H alfa emission and shape and radial velocity of He I 5875 are modulated with the long cycle. The long cycle is explained as a relaxation cycle in the circumprimary disc, that cumulates the mass transferred from the donor until certain instability produces disc depletion.
V393 Scorpii is a member of the subclass of Algols dubbed Double Periodic Variables (DPVs). These are semidetached binaries with B-type primaries showing a long-photometric cycle lasting in average 33 times the orbital period. We describe the behavior of unreported metallic emission lines in the cool stellar component of this system. The emissions can be single or double for a same line and sometimes show velocity shifts regarding the velocity of the center of mass of the star. In addition, these lines are stronger during the high state. This behavior suggests the presence of active regions in the surface of the rapidly rotating A7 donor covering a fraction of the visible hemisphere, which have larger emissivity during the high state. Our finding supports the recently proposed dynamo model for the long cycle of DPVs proposed by Schleicher & Mennickent. The model predicts an increase of the dynamo number of the donor during epochs of mass transfer in this system, and a theoretical long/orbital period ratio very close to the observed one at the present system age.
We describe the results of the world-wide observing campaign of the highly eccentric Be binary system delta Scorpii 2011 periastron passage which involved professional and amateur astronomers. Our spectroscopic observations provided a precise measurement of the system orbital period at 10.8092+/- 0.0005 years. Fitting of the He II 4686A line radial velocity curve determined the periastron passage time on 2011 July 3, UT 9:20 with a 0.9--day uncertainty. Both these results are in a very good agreement with recent findings from interferometry. We also derived new evolutionary masses of the binary components (13 and 8.2 Msun) and a new distance of 136 pc from the Sun, consistent with the HIPPARCOS parallax. The radial velocity and profile variations observed in the H_alpha line near the 2011 periastron reflected the interaction of the secondary component and the circumstellar disk around the primary component. Using these data, we estimated a disk radius of 150 Rsun. Our analysis of the radial velocity variations measured during the periastron passage time in 2000 and 2011 along with those measured during the 20th century, the high eccentricity of the system, and the presence of a bow shock-like structure around it suggest that delta Sco might be a runaway triple system. The third component should be external to the known binary and move on an elliptical orbit that is tilted by at least 40 degree with respect to the binary orbital plane for such a system to be stable and responsible for the observed long-term radial velocity variations.
S106 is one of the best known bipolar HII regions, thoroughly studied and modelled at infrared, submillimeter and millimeter wavelengths, and it is one of the nearest examples of the late stages of massive star formation in which the newly formed star that ionizes it is still surrounded by vast amounts of gas and dust. However, little is known about its heavily obscured central source, S106IR. The possible binarity of the central source is investigated, which is considered to be likely given the high binarity fraction among massive stars. We have carried out visible and near-infrared photometric monitoring looking for short-term variability, with special interest in that related to the presence of a close binary companion to S106IR that may produce periodic eclipses or tidal distortion of the shape of the members of the system. A periodic variability of S106IR in the J band is found with a period of 5.0 days and an amplitude of about 0.1 mag. The light curve displays a slow rise from minimum to maximum followed by a steep decrease, and can be well reproduced by a close binary system composed of two stars with different luminosity orbiting each other in an elliptical orbit of moderate eccentricity. S106IR also shows hints of short-term variability possibly related to accretion. We also report variability of four other stars previously classified as members of the S106 cluster, all of which are strong X-ray emitters. The newly discovered close binarity of S106IR adds a new element to the modeling of the nebula and to the understanding of the dynamics of the gas around the ionizing source, which suggests that the components of the binary are accreting via a circumbinary disk. Binarity also helps to explain the apparent mismatch between the spectral type of the ionizing source inferred from the nebular spectrum and its high brightness at near-infrared wavelengths.
The types of instability in the interacting binary stars are reviewed. The project Inter-Longitude Astronomy is a series of smaller projects on concrete stars or groups of stars. It has no special funds, and is supported from resources and grants of participating organizations, when informal working groups are created. Totally we studied 1900+ variable stars of different types. The characteristic timescale is from seconds to decades and (extrapolating) even more. The monitoring of the first star of our sample AM Her was initiated by Prof. V.P. Tsesevich (1907-1983). Since more than 358 ADS papers were published. Some highlights of our photometric and photo-polarimetric monitoring and mathematical modelling of interacting binary stars of different types are presented: classical, asynchronous, intermediate polars and magnetic dwarf novae (DO Dra) with 25 timescales corresponding to different physical mechanisms and their combinations (part Polar); negative and positive superhumpers in nova-like and many dwarf novae stars (Superhumper); eclipsing non-magnetic cataclysmic variables; symbiotic systems (Symbiosis); super-soft sources (SSS, QR And); spotted (and not spotted) eclipsing variables with (and without) evidence for a current mass transfer (Eclipser) with a special emphasis on systems with a direct impact of the stream into the gainer stars atmosphere, or V361 Lyr-type stars. Other parts of the ILA project are Stellar Bell (interesting pulsating variables of different types and periods - M, SR, RV Tau, RR Lyr, Delta Sct) and Novice(=New Variable) discoveries and classification with a subsequent monitoring for searching and studying possible multiple components of variability. Special mathematical methods have been developed to create a set of complementary software for statistically optimal modelling of variable stars of different types.
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