The Noah Project: detection of the spin-orbit beat period of BY Camelopardalis

Silber, A.; Szkody, Paula; Hoard, D. W.; Hammergren, M.; Morgan, J. S.; Fierce, E.; Olsen, Knut; Mason, Paul; Rolleston, Robert J.; Ruotsalainen, Robert; Павленко, Е. П.; Shakhovskoy, N. M.; Shugarov, S. Yu.; Андронов, И. Л.; Колесников, С. В.; Naylor, T.; Schmidt, Edward G.

doi:10.1093/mnras/290.1.25

Cited by 35 publications

(55 citation statements)

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“…Taking the different pieces of evidence together, Silber et al (1997) concluded that this shorter period must be the 2ω − Ω sideband frequency, thus indirectly validating P spin and P orb at or close to the values found by Mason et al (1989) and Sauter (1992). If this interpretation is correct, BY Cam has a beat period of ∼14 days, and the presence of the 2ω − Ω sideband frequency would be an indirect evidence for pole switching as predicted from the theoretical power spectra (Wynn & King 1992).…”

Section: Introductionsupporting

confidence: 63%

“…An intensive photometric campaign spanning several months of near continuous monitoring (Silber et al 1997;Mason et al 1998) led to the detection of a previously unrecognised shorter period of 197.439 min dominating the signals anticipated for P spin and P orb . Taking the different pieces of evidence together, Silber et al (1997) concluded that this shorter period must be the 2ω − Ω sideband frequency, thus indirectly validating P spin and P orb at or close to the values found by Mason et al (1989) and Sauter (1992).…”

Section: Introductionmentioning

confidence: 99%

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Doppler tomography of the asynchronous polar BY Camelopardalis

Schwarz¹,

Schwope²,

Staude³

et al. 2005

A&A

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We present phase-resolved, high-resolution (1.3 Å) spectroscopy of the brightest near-synchronous polar BY Cam taken on two different occasions in 1998 and 1999. The first tomographic study of such a system reveals line emission spread out over a large velocity range forming a crescent at negative v y velocities in the Doppler maps. In contrast to the majority of synchronous AM Her systems there is only weak indication for the presence of a focused accretion stream. These two facts suggest that the majority of the matter is accreted via an extended curtain. Location and extent of the structure in the Doppler maps can be reproduced with a simple curtain model raised over a wide (∼180• ) range in azimuth implying that the ballistic stream stretches to a point far behind the white dwarf. In order to reach such small magnetospheric radii mass accretion rates a factor of 10 to 20 in excess of that normally seen in polars would be required. In addition to the curtain emission, the Balmer lines show a narrow emission line component likely originating from the heated side of the secondary star. Its velocity amplitude of 190 km s −1 together with an illumination model of the secondary star suggests a rather heavy white dwarf of M 1 ≥ 0.8 M and an inclination larger than i ≥ 40• . Timings of this feature in the present and historical data unequivocally determine the orbital period and have been used to establish a high-precision, long-term ephemeris.

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Section: Introductionsupporting

confidence: 63%

Section: Introductionmentioning

confidence: 99%

Doppler tomography of the asynchronous polar BY Camelopardalis

Schwarz¹,

Schwope²,

Staude³

et al. 2005

A&A

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“…For the case of two-column accretion in the intermediate polar RXS J062518+733433, Kim et al (2005) discovered variability of the spin phases with orbital phase. For switching accretion from one pole to another in the asynchronous polar BY Cam, the phases show a "tooth-like" curve with abrupt changes by 0.5 (Silber et al 1997). For V1432 Aql, our observations span 18 d = 0.3P beat , so one cannot obtain firm conclusions on the periodicity of phases, even though such a character of variability may not be excluded.…”

Section: Spin Period Of the White Dwarfmentioning

confidence: 60%

The unique magnetic cataclysmic variable V1432 Aql

Андронов¹,

Baklanov

Burwitz

2006

A&A

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Results of a CCD study of the variability of the unique magnetic cataclysmic variable V1432 Aql from the Astronomical Observatory of Mallorca are presented. The "multi-comparison star" method had been applied for better accuracy estimates. The linear ephemeris based on 76 timings of orbital eclipses for 1993-2004 is HJD min = 2 451 492.09876(14) + 0.140235812(12) · E. For the wide minima due to the spin variability, the quadratic ephemeris HJD spin = 2 449 638.327427(74) + 0.14062831(23) · E − 7.81(11) × 10 −10 E 2 was determined. The rate of the spin-up of the white dwarf corresponds to the synchronization time-scale determined to be (96.7 ± 1.5) years, in an agreement with theoretical model of the accretion torque. A third type of minima was detected that occur with the spin period. It was interpreted as indicating presence of the second accretion column. For adopted values of mass M 1 = 0.9 M and M 2 = 0.3 M , the estimated accretion rate is ∼7 × 10 −10 M /yr. Further multi-colour monitoring is needed to study of late stages of the "spin-orbital" synchronization and periodic changes of the accretion geometry caused by "idling" of the white dwarf.

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“…The presence of this periodicity has been predicted for the power spectra of disk-less asynchronous magnetic CVs and can be taken as evidence of alternating accretion onto two diametrically opposed poles (Wynn & King 1992). This signal has been reported for two of the four asynchronous polars: BY Cam (Silber et al 1997;Mason et al 1998) and CD Ind (Ramsay et al 1999). The detection of this signal in these systems required extensive coverage over several beat cycles, whereas smaller data sets emphasise signals near the putative spin period.…”

Section: Period Analysismentioning

confidence: 78%

Paloma (RX J0524+42): the missing link in magnetic CV evolution?

Schwarz¹,

Schwope²,

Staude³

et al. 2007

A&A

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Decent optical photometry of the canditate magnetic CV Paloma has uncovered three persistent periods at 157, 146, and 136 min, which we interpret as the manifestation of the orbital motion of the system, the white dwarf's spin, and a related side-band frequency of the other two. All three periodicities are caused by a double-humped modulation of about 1 mag appearing only at certain fractions of the beat cycle, and it probably originates from one or two accretion spots. Our data is consistent with two plausible solutions, with the spin period being either 146 or 136 min. The appearance of a corresponding spin-folded light curve suggests two different scenarios, for which either pole switching between two diametrically opposed accretion regions (for P spin = 146 min) or pole migration of one single spot (with P spin = 136 min) is the preferred accretion mode. Complementary ROSAT X-ray observations and low-resolution spectroscopy provide supporting evidence of the magnetic nature of the object. Depending on the choice of the spin period, the degree of asynchronism with respect to the orbital period is 7% or 14%, implying a beat period of 0.7 or 1.4 days. Thus, the source populates the gap between the near-synchronous polars (<2%) and the DQ Herculis stars with long spin periods (e.g. EX Hya, V1025 Cen, DW Cnc). With an orbital period right within the period gap, Paloma is a key object for magnetic CV evolution: it might be the first bona fide transition object between the DQ Her and AM Her system with a white dwarf currently in the process of synchronisation.

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The Noah Project: detection of the spin-orbit beat period of BY Camelopardalis

Cited by 35 publications

References 0 publications

Doppler tomography of the asynchronous polar BY Camelopardalis

Doppler tomography of the asynchronous polar BY Camelopardalis

The unique magnetic cataclysmic variable V1432 Aql

Paloma (RX J0524+42): the missing link in magnetic CV evolution?

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