Algol-type System Research Articles

Evolution of close binaries under the assumption that they lose angular momentum by a magnetic stellar wind

A simple method is proposed for describing the evolution of semidetached close binaries whose secondary components have degenerated helium cores and lose orbital angular momentum by a magnetic stellar wind. The results of calculations are used to estimate the initial parameters of a series of low-mass (M/sub 1/ + M/sub 2/ less than or equal to 5M.) systems of Algol type under the two assumptions of conservative and nonconservative evolution with respect to the orbital angular momentum. Only the assumption that the systems with secondary components possessing convective shells lose angular momentum makes it possible to reproduce their initial parameters without contradiction.

Mass Transfer and Evolution in Long-Period Binary Systems

In the earliest studies of close binary evolution (Paczynski 1967; Kippenhahn, Kohl, and Weigert 1967; Plavec, et al. 1968), it was assumed that the total mass and orbital angular momentum of a binary system are conserved during mass transfer. This assumption of convenience actually succeeds quite well in producing model post-mass-transfer binaries which closely resemble classical Algol-type systems, and helium-star binaries such as KS Per and u Sgr as well (Plavec 1973; Schonberner and Drilling 1983). Among longer-period interacting binaries, however, there are strong reasons to believe that these simple assumptions break down. For example, it is well-known that single stars may lose a very substantial fraction of their mass in a stellar wind during ascent of the giant and asymptotic-giant branches (e.g., Kudritzki and Reimers 1978). In addition, many highly-evolved short-period binaries, such as the cataclysmic variables, appear to owe their origins to very long-period progenitors (Paczynski 1976; Ritter 1976; Webbink 1976). These latter systems evidently evolved through a common envelope phase (Paczynski 1976; Meyer and Meyer-Hofmeister 1979), in which the giant progenitor of the present white dwarf devoured its companion star, and ultimately was divested of its envelope by the release of orbital energy as that companion spiralled toward its core.

UBV photometry of FK Comae

UBV photometry of the peculiar star FK Comae, obtained during the period January–June 1983, is presented. The amplitude of the photometric variation has raised with respect to the previous observations performed in 1981 and 1982, attaining about 0.18 mag in theV filter. Colour curves indicate that the star is redder at minimum light; this fact is consistent with both the models presented to explain the properties of FK Comae. A Fourier analysis of the light curves available in the literature has been performed; the phases of minimum and maximum light turn out to be noticeably stable in time. This fact is difficult to be reconciled with the hypothesis of dark spots that are observed to migrate in other active stars. Rather, it could be explained by the model of Walter and Basri (1982a, b), implying an extremely evolved Algol-type system accreting mass on its primary component.

Physical properties of V1329 Cygni

In this paper, I shall present another model for V1329 Cyg. Grygar et al. (1979) proposed a long period eclipsing binary model consisting of a massive M giant and a hot component. Some problems, however, have remained on the binary model. Namely, the mass function is too large, the amplitude of the light variations changes from period to period, the light curve differs from that of Algol type systems and is similar to long period binaries, and so on (Iijima et al. 1981). It has been believed that some peculiarities in the system could explain those problems. Recently however, some phenomena which are inconsistent with the binary model were observed (Iijima and Mammano 1981).

Close binary systems before and after mass transfer. II.Semi-detached systems

Recent data on semi-detached systems are compared with general results of close binary computations to determine the origin of Algol-type systems (classical case A and case B results are considered). Both the conservative and the non-conservative mode of mass exchange are investigated. It is found that the assumption of considerable mass loss from the system gives satisfying agreement with the observations. It is also concluded that the calculation of an extensive homogeneous network of case A computations is needed.

HR 5110 - an Algol-type system with RS CVn properties

view Abstract Citations (16) References (24) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS HR 5110 - an Algol-type system with RS CVn properties. Dorren, J. D. ; Guinan, E. F. Abstract Intermediate- and narrowband H-alpha and Stromgren y and u photometry of the RS CVn-type variable HR 5110 is presented. The Wilson-Devinney program is employed to fit existing data, and the results confirm Hall's suggestion that the low-amplitude (0.010 m) light variation is attributable to the reflection effect. HR 5110 has also been classified as an Algol-type system of low inclination (about 13 deg) and it is suggested that Algol-type systems might often contain secondaries with highly active chromospheres but have not been classified as RS CVn-type variables because the light from the system is dominated by the primary component. Publication: The Astronomical Journal Pub Date: August 1980 DOI: 10.1086/112771 Bibcode: 1980AJ.....85.1082D Keywords: Algol; Binary Stars; Stellar Models; Stellar Spectrophotometry; Variable Stars; Companion Stars; H Alpha Line; K Lines; Light Curve; Optical Reflection; Radio Bursts; Visual Photometry; Astrophysics full text sources ADS | data products SIMBAD (2)

Narrow Band Photometry and Observable Effects in Algol Type Systems

The application of narrow band photometry to Algol type systems is considered and advantageous circumstances pointed out. Observable effects can be divided into two kinds: classical (associated essentially with differential centre to limb variation) and interactive (where an emission component may be present in the line). Observations of U Sge and β Per are discussed from this basis and deductions made about the size and shape of an emitting region. Conclusions are compared with theoretical ideas about such regions and their expected stability, both for these and other similar systems.

Evolution of close binaries and origin of Algol-type systems

Evolution of close binaries and origin of Algol-type systems

The eclipsing binary system BV 430

The Algol-type eclipsing binary BV 430 was studied photoelectrically in ydlow and blue light at the newly founded Mount John University Observatory on the South Island of New Zealand. New light elements are obtained, the period being given as ld.6698684. The eclipses of BV 430 are not complete. The primary minimum is a transit. BV 430 is typical of Algol-type systems with similar components.