Eclipsing behaviour of the radio emission in the Algol system V505 Sagittarii

Gunn, Alastair G.; Brady, P. A.; Migenes, V.; Spencer, R. E.; Doyle, J. G.

doi:10.1046/j.1365-8711.1999.02362.x

Cited by 16 publications

(25 citation statements)

References 43 publications

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“…The number 0.125 has been taken between 0.1 and 0.15, numbers which are valid using solar abundances for respectively a neutral gas and a completely ionized plasma. The quantity S = (Budding et al 2001) and V505 Sgr (Gunn et al 1999), showing a fair agreement with the results from expression (24).…”

Section: Gauging the Quantity Ssupporting

confidence: 85%

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Spin-up and hot spots can drive mass out of a binary

Greve¹,

Loore²,

Mennekens³

2008

A&A

100

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Context. The observed distribution of orbital periods of Algols with a B-type primary at birth agrees fairly well with the prediction from conservative theory. Conservative evolution fails, however, to produce the rather large fraction of Algols observed with a high mass-ratio, especially: q ∈ [0.4-0.6]. Aims. In order to keep Algols for a longer time with a higher mass-ratio without disturbing the distribution of orbital periods too much, interacting binaries have to lose a significant fraction of their total mass without losing much angular momentum before or during Algolism. We propose a mechanism that meets both requirements. Methods. In the case of direct impact the gainer spins up: sometimes up to critical velocity. Equatorial material on the gainer is therefore less bound. A similar statement applies to material located at the edge of an accretion disc. The incoming material moreover creates a hot spot in the area of impact. The sum of the rotational and radiative energy of hot spot material depends on the masstransfer-rate. The sum of both energies overcomes the binding energy at a well defined critical value of the mass-transfer-rate. As long as the transfer-rate is smaller than this critical value RLOF happens conservatively. But as soon as the critical rate is exceeded the gainer will acquire no more than the critical value and RLOF runs into a liberal era. Results. Low-mass binaries never achieve mass-transfer-rates larger than the critical value. Intermediate-mass binaries evolve mainly conservatively but mass will be blown away from the system during the short era of rapid mass-transfer soon after the onset of RLOF. We have calculated the evolution of binaries with a 9 M primary and a 5.4 M companion over a range of initial orbital periods, covering case-A RLOF. Mass-loss from the system is achieved during direct impact only. Conclusions. We find systems that show Algolism for more than ten million years. RLOF occurs almost always conservatively. Only during some 20 000 years the gainer is not capable of grasping all the material that comes from the donor. The mass-ratio q ∈ [0.4-0.6] which was hardly populated by conservative evolution now contains Algols for a significant fraction of their existence.

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Section: Gauging the Quantity Ssupporting

confidence: 85%

“…Gunn et al (1999) use an expression of Pringle (1985) giving the area of the cross section of the stream starting from the first Lagrangian point L 1 with the local sonic speed v sonic towards the gainer, for the calculation of the surface area of a hot spot around the impact point P:…”

Section: Calibrating the Quantities A And Smentioning

confidence: 99%

Spin-up and hot spots can drive mass out of a binary

Greve¹,

Loore²,

Mennekens³

2008

A&A

100

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“…They detected a modulation in the EUV and radio flux levels which led them to suggest the existence of an intra-binary region of activity. Gunn et al (1999) found a similar region on the Algol system V505 Sgr. These intra-binary regions would imply a joint magnetosphere and possible interaction between magnetic loops between the two components of the binary system.…”

Section: Resultsmentioning

confidence: 55%

Doppler images of the RS CVn binary HR 1099 (V711 Tau) from the MUSICOS 1998 campaign

García-Álvarez

Barnes

Cameron

et al. 2003

A&A

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Abstract. We present Doppler Images of the RS CVn binary system HR 1099 (V711 Tau) from spectra taken in two different sites, KPNO and MSO, during the MUSICOS 1998 campaign. Contemporaneous APT photometry is used to constrain the Doppler Images. The resulting maximum entropy reconstructions based on the least-squares deconvolved profiles, derived from ∼2000 photospheric absorption lines, reveal the presence of starspots at medium-high latitudes. We have obtained maps for both components of the binary system for the first time. The predominant structure in the primary component is an offcentered polar spot, confirming previous works on the same target by using independent codes. The result is verified by using both data sets independently. The lower spectral resolution data set gives a less detailed map for the MSO data set. The images obtained for the secondary component show a low latitude spot around orbital phase 0.7. This spot seems to mirror the structure seen on the primary. It might suggest that tidal forces may influence the spot distribution on this binary system. Key words. stars: binaries: spectroscopic -stars: late-type -stars: individual: HR 1099 -stars: activity -stars: imagingstars: starspots IntroductionRS CVn binary systems consist of a chromospherically active evolved star tidally locked to a main-sequence or subgiant companion. Short orbital periods ranging from a few days to 20 days are typically observed. The RS CVn high level of activity has been measured from radio to hard X-rays and, for fast rotators, it approaches the saturation limits for chromospheric, transition region and coronal emission. One of the striking aspects of these systems is their propensity to flare (Donati et al. 1992;García-Alvarez et al. 2003). Moreover, RS CVns show optical photometric variations which are believed to arise from the rotational modulation of photospheric spots (Rodonò et al. 1986;Byrne et al. 1995), large scale versions of dark solar spots, that provide evidence for large-scale magnetic fields. Donati (1999) and Donati et al. (2003) showed that Zeeman Doppler Imaging can also provide evidence of such magnetic structures. Short-period RS CVn-like systems, through their rotational modulation, can then provide information on the morphology and two-dimensional structure of active regions in stellar atmospheres. Deutsch (1958Deutsch ( , 1970 first proposed the use of line profiles as a tool to map stellar surfaces. Goncharsky et al. (1977) developed the first inversion technique with regularization, but it was Vogt & Penrod (1983) who first called it Doppler Imaging. The technique exploits the correspondence between the wavelength position across a rotationally broadened spectral line and the spatial position across the stellar disk at a given rotation phase. Vogt (1987) addressed the difficulties in inverting the spectral line profiles into an image of the stellar disk. Doppler imaging has provided one of the few direct pieces of evidence for the existence of starspots, or localised plages, but the tech...

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“…High-energy mechanisms are revealed through light curves from X-ray wavelengths (Stelzer et al 1999). Radioastronomy too has seen remarkable advances in both sensitivity and resolution capability, permitting fuller geometrical insights into the Algol configuration (Mutel et al 1998;Richards et al 1998;Lestrade et al 1999;Gunn et al 1999). Optical astrometry (e.g.…”

Section: Introductionmentioning

confidence: 99%

Catalogue of Algol type binary stars

Budding

Erdem

Çiçek

et al. 2004

A&A

135

123

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Abstract.A catalogue of (411) Algol-type (semi-detached) binary stars is presented in the form of five separate tables of information. The catalogue has developed from an earlier version by including more recent information and an improved layout. A sixth table lists (1872) candidate Algols, about which fewer details are known at present. Some issues relating to the classification and interpretation of Algol-like binaries are also discussed.

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Eclipsing behaviour of the radio emission in the Algol system V505 Sagittarii

Cited by 16 publications

References 43 publications

Spin-up and hot spots can drive mass out of a binary

Spin-up and hot spots can drive mass out of a binary

Doppler images of the RS CVn binary HR 1099 (V711 Tau) from the MUSICOS 1998 campaign

Catalogue of Algol type binary stars

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