Photometric study of the active Algol system RZ Cassiopeiae

Narusawa, S.; Nakamura, Yasuhisa; Yamasaki, A.

doi:10.1086/116926

Cited by 16 publications

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“…The primary minimum is a partial eclipse (Narusawa et al 1994) and the light-curve is distorted, possibly by star spots (e.g. Maxted et al 1994) and/or by non-symmetric circumstellar matter (Olson 1982; Send offprint requests to: H. Lehmann, e-mail: lehm@tls-tautenburg.…”

Section: Introductionmentioning

confidence: 99%

The eclipsing binary star RZ Cas

Lehmann

Mkrtichian

2003

A&A

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Abstract. In a first report on the results of a multi-site campaign in 2001 of photometric and spectroscopic observations of the active semi-detached Algol-type system RZ Cas, we concentrate on the radial velocity (RV) variations. Using weak absorption lines we obtain an improved orbital solution for both components. In the orbital RV curve we observe a strong, asymmetric rotation effect. For the first time we detect rapid spectroscopic multi-mode pulsations in an Algol system. Whereas the photometrically observed oscillations were dominated by monoperiodic pulsations at frequency 64. . Both modes show amplitude variations over the orbital phase with a a minimum at orbital phases φ = 0.6-0.8 and a maximum just after the primary minimum ( f 2 ) and at φ ≈ 0.25 ( f 1 ). The different shape of amplitude modulation of the f 1 and f 2 modes points to different (l, m) mode structures. The modulation itself can be explained by assuming a variable extinction due to gas streams and an inhomogeneous accretion annulus that weakens the light from different regions of the primary depending on its orbital position. This assumption is well supported by the gas density distribution obtained in preliminary hydrodynamic simulations. We found strong variations and cycle-to-cycle variable shapes of the orbital RV-curves of Balmer lines that have maximum magnitude in the Hα line indicating a strong variability of mass-transfer rates and a non-stationary circumbinary envelope.

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Section: Introductionmentioning

confidence: 99%

The eclipsing binary star RZ Cas

Lehmann

Mkrtichian

2003

A&A

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“…Our orbital solutions yield different values of the orbital period based on the spectra taken in 2001 and 2006 and a significantly different value of the orbital period derived from the spectra taken in 2006 compared to Narusawa's period (Narusawa et al 1994). According to our solution S 2 , the orbital period increased from 2001 to 2006 by 1.6 s. This result is in agreement with the photometric findings from the analysis of the observed times of minima.…”

Section: The Orbitmentioning

confidence: 59%

“…Compared to his value of P = 1.1952572(6) d, our period from solution S 2006 shows an increase by 3.2 ± 0.5 d. Period changes of RZ Cas of a number of seconds have been repeatedly observed. Narusawa et al (1994) reported an increase in the orbital period by 1.5 s between 1988 and 1990. A detailed analysis of the time of minima observations will be given in a forthcoming paper.…”

Section: The Orbitmentioning

confidence: 99%

“…Starting with the assumption of circular orbits we derived orbital elements separately (columns S 2001a and S 2006 in Table 2) Narusawa et al (1994) from the photometric times of minima calculated from the measurements by Nakamura (1991). The values of the orbital period given by S 2001a , S 2006 , and by Narusawa et al (1994) differ significantly within its limits of errors. We obtain a difference of 30 s between the spectroscopic orbits from 2006 and 2001.…”

Section: Primary Orbitmentioning

confidence: 99%

“…Its orbital period is of 1.1952572 d and the primary minimum is a partial eclipse (Narusawa et al 1994). The primary component was discovered as a 22.4 min period oscillating star by Ohshima et al (1998Ohshima et al ( , 2001.…”

Section: Introductionmentioning

confidence: 99%

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The eclipsing binary star RZ Cassiopeiae

Lehmann

Mkrtichian

2008

A&A

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Aims. We test the hypothesis that the oEA star RZ Cas has undergone a transient phase of rapid mass-transfer in 2000/2001. Methods. We analyze a time series of high-resolution spectra of RZ Cas obtained in 2001 and in 2006 for radial velocity (RV) and line profile variations. Improved orbital solutions are determined using the method of differential corrections. In the RV residuals, after subtracting the orbital solution and low-frequency variations, we search for non-radial pulsations in the high-frequency domain and for an amplitude modulation of the pulsation modes.We model the observed line profiles using a new computer program based on the method of spectroscopic eclipse mapping and investigate the line intensity residuals and the Rossiter-McLaughlin effect.

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VLA and MERLIN observations of RZ Cassiopeiae

Gunn

Brady

2003

Monthly Notices of the Royal Astronomical Society

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We present radio interferometric observations of the Algol‐type binary system RZ Cassiopeiae made with the VLA and MERLIN arrays at 6 cm over an incomplete orbital cycle of the system (1.195 d). We detected RZ Cas with both instruments. The images were unresolved in both cases, with angular extents comparable to the synthesized beams. The peak flux density in the VLA image was 1.14 mJy beam−1 and in the MERLIN image it was 0.93 mJy beam−1. The derived brightness temperatures are 4.02 × 108 and 4.35 × 108 K and the effective electron energies are 0.347 and 0.346 MeV for the MERLIN and VLA data respectively. The radio light curve shows an interesting modulation centred close to the primary eclipse which seems to correlate with ASCA SIS observations of the system. The results can be interpreted as an emitting region on the outer hemisphere of the cool component aligned along the centroid axis of the binary system.

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Photometric study of the active Algol system RZ Cassiopeiae

Cited by 16 publications

References 0 publications

The eclipsing binary star RZ Cas

The eclipsing binary star RZ Cas

The eclipsing binary star RZ Cassiopeiae

VLA and MERLIN observations of RZ Cassiopeiae

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