Morphologies of Hα Accretion Regions in Algol Binaries

Abstract

We have investigated a group of 18 Algol-type binaries to determine the general morphologies and physical properties of the accretion regions in these systems. The systems studied were V505 Sgr, RZ Cas, AI Dra, TV Cas, TW Cas, d Lib, RW Tau, TW Dra, b Per, TX UMa, U Sge, S Equ, U CrB, RS Vul, SW Cyg, CX Dra, TT Hya, and AU Mon, in order of increasing orbital period P \ 1.18È11.11 days. In addition, the RS CVn-type binary HR 1099 (V711 Tau) was observed to illustrate the appearance of chromospheric Ha emission. Nearly 2200 time-resolved Ha spectra were collected from 1992 March to 1994 December with the McMath-Pierce Solar Telescope at NSO and mostly with the Coude Feed Telescope at KPNO. The spectra were obtained at phases around the entire orbit of each binary and were closely spaced to permit the detection of transitions in the proÐles. Moreover, the spectra were obtained typically within three orbital cycles to reduce the inÑuence of secular variations. Di †erence proÐles were calculated by subtracting a composite theoretical photospheric spectrum from the observed spectrum.The analysis of the Ha di †erence proÐles demonstrates that the accretion structures in Algol binaries have four basic morphological types : (1) double-peaked emission systems in which the accretion structure is a transient or classical accretion disk ; (2) single-peaked emission systems in which the accreted gas was found along the trajectory of the gas stream and also between the two stars in an accretion annulus ; (3) alternating single-and double-peaked emission systems, which can change between a single-peaked and a double-peaked type within an orbital cycle ; and (4) weak spectrum systems in which there was little evidence of any accretion structure since the di †erence spectra are weak at all phases. The Ðrst two types are the dominant morphologies. The Ðrst type can be interpreted physically as a disklike distribution, while the second is a gas streamÈlike distribution.The most common type in short-period Algols with 2.7 days \ P \ 4.5 days is a predominantly singlepeaked emission feature in the Ha di †erence proÐles (Type 2). This feature is redshifted during the phase interval / D 0.15È0.45 and blueshifted from / D 0.55È0.85. This single-peaked emission is often composed of two closely spaced emission peaks where one peak is at the Ha rest wavelength. The other peak is blueshifted at / D 0.65, where the line of sight is along the length of the approaching gas stream. Systems which display this morphology include RZ Cas, RW Tau, TW Dra, b Per, TX UMa, S Equ, and RS Vul. The orbital variation of the Ha observed proÐles of HR 1099 was similar to that seen in the di †erence spectra of this group and suggests that chromospheric emission may play a signiÐcant role in these binaries. A less common morphological type in the group of short-period Algols was a widely separated double-peaked disk-like distribution (Type 1) where the gas is in a transient or classical accretion disk. All of the long-period systems (P [ 6 days) were f...

H$\boldmath{\alpha}$ variations of the RS CVn type binary ER Vulpeculae

“…Richards & Albright 1999). Evidence for inter-system matter, emitting and absorbing at Hα wavelengths, has been also recently reported by Marino et al (2001) for HR 7428, a long-period, detached atypical RS CVn binary composed of a bright K-type giant and an A-type star.…”

Mass loss out of close binaries

“…Manzoori & Gozaliazl (2007) have determined a value forṖ (thusṀ) and have seen a hot spot on the gainer's surface for which a range of temperatures is given by Richards & Albright (1999). A value for L add has been determined by Albright & Richards (1996), which makes this binary a well-described system.…”

“…-SW Cyg: masses, radii, and effective temperatures can be found in the catalog of Budding (2004) and Richards & Albright (1999). Values forṖ (and thusṀ) are from Qian et al (2002).…”

Orbital Period Changes of Algol-type Binaries: S Equulei and AB Cassiopeiae

“…The secular period increase rates were obtained as DP=P ¼ 0:102 s yr À1 and DP=P ¼ 0:03 s yr À1 for S Equ and AB Cas, respectively, requiring mass transfer rates of about dM=dt ¼ 3:97 Â 10 À8 M yr À1 and dM=dt ¼ 5:6 Â 10 À8 M yr À1 from Roche lobe-filling low-mass secondaries to the primaries. Richards & Albright (1999) reported that S Equ shows emission lines in its spectra due to an accretion disk structure resulting from mass transfer. In addition, Vesper et al (2001) showed, using spectral data, that the system has an accretion structure.…”

“…The spectral types of the hotter and cooler components are B7 V and G8 III, respectively (Plavec 1983). Its spectra show single-peaked emission features with additional weak double-peaked emission at some epochs, indicating mass transfer activity and disk structure around the primary component (see, e.g., Richards & Albright 1999;Vesper, Honeycutt, & Hunt 2001). Although OÀC curves were published by several authors (Plavec 1966;Kreiner 1971), there was has been no detailed period study of the system.…”