Psychiatric Units in General Hospitals

Watson, J. P.; Bennett, Douglas; Isaacs, A. D.

doi:10.1016/s0140-6736(70)91592-8

Cited by 17 publications

(15 citation statements)

References 10 publications

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“…The pole switching in a desynchronized polar (e.g. Mason et al 1998) and/or reconnection events in the magnetic field lines connecting the primary and the secondary could produce just the conditions to explain the unusual radio flare in FIRST J1023+0038; but in any case, the independent deduction of the presence of a strong magnetic field is compatible both with the spectrum and the existence of radio emission.…”

Section: Observationsmentioning

confidence: 99%

High-speed photometry of faint cataclysmic variables - IV. V356 Aql, Aqr1, FIRST J1023+0038, Hα 0242-2802, GI Mon, AO Oct, V972 Oph, SDSS 0155+00, SDSS 0233+00, SDSS 1240−01, SDSS 1556−00, SDSS 2050−05, FH Ser

Woudt

Warner

Pretorius

2004

Monthly Notices of the Royal Astronomical Society

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We present results from high‐speed photometry of a further 13 faint cataclysmic variables. V356 Aql (Nova Aql 1936) shows flare‐like outbursts with recurrence time‐scales ∼3000 s, but no coherent periodicities. Aqr1 is an intermediate polar with a spin period of 6.7284 min and a probable orbital period Porb= 3.226 h derived from orbital sidebands. Its orbital sideband frequencies show very variable amplitudes. The published spectroscopic period of 2.0 h suggests that Aqr1 is similar to GW Lib and FS Aur in having an additional periodicity of unknown origin. FIRST J1023+0038 has Porb= 4.7548 h with an orbital modulation of range 0.45 mag, probably caused by reflection effect from a hot white dwarf primary; as such it may have been a nova sometime in the past few decades. Hα 0242 is a deeply eclipsing very low mass‐transfer rate system, probably a dwarf nova of very long outburst interval, with Porb= 1.792 h. GI Mon, an old nova, has optical modulations at 4.325 h and possibly also at 48.6 min and is thus a candidate intermediate polar. AO Oct, an SU UMa type dwarf nova, shows orbital modulation at quiescence with Porb= 94.097 min. V972 Oph (Nova Ophiuchi 1957) showed no flickering activity during one set of observations, but did so at a later time, confirming the correctness of the identification of this object, but it shows no orbital modulation. SDSS 0155 is a deeply eclipsing polar with an orbital period of 87.13 min. SDSS 0233 shows flaring activity but no discernible periodicity. No periodicity was found in the new AM CVn candidate SDSS 1240. SDSS 1556 shows a periodic modulation at 1.778 h, which is possibly due to orbital motion. SDSS 2050 is an eclipsing polar with Porb= 1.5702 h. FH Ser (Nova Serpentis 1970) has strong flickering activity but no detectable orbital modulation.

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Section: Observationsmentioning

confidence: 99%

High-speed photometry of faint cataclysmic variables - IV. V356 Aql, Aqr1, FIRST J1023+0038, Hα 0242-2802, GI Mon, AO Oct, V972 Oph, SDSS 0155+00, SDSS 0233+00, SDSS 1240−01, SDSS 1556−00, SDSS 2050−05, FH Ser

Woudt

Warner

Pretorius

2004

Monthly Notices of the Royal Astronomical Society

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“…One of the brightest of these asynchronous polars is BY Cam. It is bright in X‐rays and has an binary orbital period of 201.258 min and a white dwarf with a spin period of 199.330 min (Mason et al 1998). This results in a spin‐orbit beat period of 14.5 d.…”

Section: Introductionmentioning

confidence: 99%

“…Indeed, it was discovered using the X‐ray satellite Uhuru by Forman et al (1978). Since then it has been observed using EXOSAT (Shrader et al 1988), Ginga (Ishida et al 1991; Done & Magdziarz 1998), ASCA (Kallman et al 1996; Done & Magdziarz 1998), ROSAT (Ramsay et al 1994; Mason et al 1998) and BBXRT (Kallman et al 1993). These observations have shown a highly variable X‐ray light curve.…”

Section: Introductionmentioning

confidence: 99%

XMM-Newton observations of the asynchronous polar BY Cam

Ramsay

Cropper

2002

Monthly Notices of the Royal Astronomical Society

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We report observations of the asynchronous polar BY Cam made using XMM-Newton. We find evidence for two accretion regions which have significantly different spectra. In both regions we find evidence for hard X-ray emission from the post-shock flow while we observe a distinct soft X-ray blackbody component in only one. We detect two emission lines in the RGS detectors which we attribute to Nitrogen NVI and NVII: the first time that Nitrogen lines have been detected in an X-ray spectrum of a cataclysmic variable. In the time interval where we observe short timescale variability we find the hard X-ray light curve is correlated with the softest energies in the sense that the hard X-rays trail the soft X-rays and are anti-correlated. We suggest that there are a small number of dense blobs of material which impact the white dwarf without forming a shock and release an amount of optically thick material which obscures hard X-rays for a short duration.

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“…However, four systems are known to be slightly (∼1 per cent) asynchronous (the near‐synchronous polars), and the accretion flow will therefore attach on to different field lines as the flow rotates around the white dwarf on the time‐scale of the spin–orbit beat period. Until very recently, observations covering a beat period have been difficult to obtain because the beat period is weeks or more (V1432 Aql: Watson et al 1995; Friedrich et al 1996; Geckeler & Staubert 1997; BY Cam: Silber et al 1997; Mason et al 1998) or the system is faint (V1500 Cyg: Stockman, Schmidt & Lamb 1988). Now a fourth system (RX J2115–5840) which is reasonably bright ( V ∼17) has been discovered with a beat period of 6.3 d (Schwope et al 1997; Ramsay et al 1999), which allows a detailed study of these systems to be undertaken for the first time.…”

Section: Introductionmentioning

confidence: 99%

Simultaneous optical polarimetry and X-ray data of the near-synchronous polar RX J2115-5840

Ramsay

Potter

Cropper

et al. 2000

Monthly Notices of the Royal Astronomical Society

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A B S T R A C TWe present simultaneous optical polarimetry and X-ray data of the near-synchronous polar RX J2115±5840. We model the polarization data using the Stokes imaging technique of Potter et al. We find that the data are best modelled using a relatively high binary inclination and a small angle between the magnetic and spin axes. We find that, for all spin±orbit beat phases, a significant proportion of the accretion flow is directed on to the lower hemisphere of the white dwarf, producing negative circular polarization. Only for a small fraction of the beat cycle is a proportion of the flow directed on to the upper hemisphere. However, the accretion flow never occurs near the upper magnetic pole, whatever the orientation of the magnetic poles. This indicates the presence of a non-dipole field with the field strength at the upper pole significantly higher. We find that the brightest parts of the hard X-ray emitting region and the cyclotron region are closely coincident.

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Psychiatric Units in General Hospitals

Cited by 17 publications

References 10 publications

High-speed photometry of faint cataclysmic variables - IV. V356 Aql, Aqr1, FIRST J1023+0038, Hα 0242-2802, GI Mon, AO Oct, V972 Oph, SDSS 0155+00, SDSS 0233+00, SDSS 1240−01, SDSS 1556−00, SDSS 2050−05, FH Ser

High-speed photometry of faint cataclysmic variables - IV. V356 Aql, Aqr1, FIRST J1023+0038, Hα 0242-2802, GI Mon, AO Oct, V972 Oph, SDSS 0155+00, SDSS 0233+00, SDSS 1240−01, SDSS 1556−00, SDSS 2050−05, FH Ser

XMM-Newton observations of the asynchronous polar BY Cam

Simultaneous optical polarimetry and X-ray data of the near-synchronous polar RX J2115-5840

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