The Spin Periods and Magnetic Moments of White Dwarfs in Magnetic Cataclysmic Variables

Norton, A. J.; Wynn, G. A.; Somerscales, R. V.

doi:10.1086/423333

Cited by 171 publications

(256 citation statements)

References 51 publications

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“…If this were the case, we would expect to observe X-ray modulations on the spin period and moreover we would also expect the spin frequency of the WD to deviate from the current value with a spin-up/down timescale ≤10 7 years (Norton et al 2008(Norton et al , 2004. However, not all hard X-ray emitting IPs need to be in equilibrium, and in fact the hard X-ray emitting AE Aqr is in a purely propellor stage, and has been showing rapid spin-down rates (Wynn et al 1997;de Jager et al 1994), as the WD spin tries to reach equilibrium for its given mass ratio and magnetic field strength.…”

Section: Discussionmentioning

confidence: 99%

Confirmation of 1RXS J165443.5–191620 as an intermediate polar and its orbital and spin periods

Scaringi

Connolly

Patterson

et al. 2011

A&A

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Aims. We investigate the physical nature of the X-ray emitting source 1RXS J165443.5−191620 through optical photometry and time-resolved spectroscopy. Methods. Optical photometry is obtained from a variety of telescopes all over the world spanning ≈27 days. Additionally, timeresolved spectroscopy is obtained from the MDM observatory. Results. The optical photometry clearly displays modulations consistent with those observed in magnetic cataclysmic variables: a low-frequency signal interpreted as the orbital period, a high-frequency signal interpreted as the white dwarf spin period, and an orbital sideband modulation. Our findings and interpretations are further confirmed through optical, time-resolved spectroscopy that displays Hα radial velocity shifts modulated on the binary orbital period. Conclusions. We confirm that 1RXS J165443.5−191620 is an intermediate polar with a spin period of 546 s and an orbital period of 3.7 h. In particular, 1RXS J165443.5−191620 is part of a growing subset of intermediate polars that display hard X-ray emission above 15 keV, white dwarf spin periods below 30 min, and spin-to-orbital ratios below 0.1.

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Section: Discussionmentioning

confidence: 99%

Confirmation of 1RXS J165443.5–191620 as an intermediate polar and its orbital and spin periods

Scaringi

Connolly

Patterson

et al. 2011

A&A

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“…Around 30 confirmed IPs are now recognised, with a further 20 or so candidate systems having been proposed 1 . Comprehensive reviews of various aspects of their behaviour are given by Patterson (1994), Warner (1995) and Norton et al (2004).…”

Section: Introductionmentioning

confidence: 99%

A precessing accretion disc in the intermediate polar XY Arietis?

Norton¹,

Mukai²

2007

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Context. XY Ari is the only intermediate polar to show deep X-ray eclipses of its white dwarf. Previously published observations with Ginga and Chandra have also revealed a broad X-ray orbital modulation, roughly antiphased with the eclipse, and presumed to be due to absorption in an extended structure near the edge of an accretion disc. The X-ray pulse profile is generally seen to be double-peaked, although a single-peaked pulse was seen by RXTE during an outburst in 1996. Aims. We intended to investigate the cause of the broad orbital modulation in XY Ari to better understand the accretion flow in this system and other intermediate polars.Methods. We observed XY Ari with RXTE and analysed previously unpublished archival observations of the system made with ASCA and XMM-Newton. These observations comprise six separate visits and span about ten years.Results. The various X-ray observations show that the broad orbital modulation varies in phase and significance, then ultimately disappears entirely in the last few years. In addition, the X-ray pulse profile shows variations in depth and shape, and in the recent RXTE observations displays no evidence for changes in hardness ratio. Conclusions. The observed changes indicates that both the pulse profile and the orbital modulation are solely due to geometrical effects at the time of the RXTE observations, rather than phase-dependent variations in photoelectric absorption as seen previously. We suggest that this is evidence for a precessing, tilted accretion disc in this system. The precession of the disc moves structures out of our line of sight both at its outer edge (changing the orbital modulation) and at its inner edge where the accretion curtains are anchored (changing the pulse profile).

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“…Hence, it appears entirely possible that HS 0943+1404 is a true "intermediate" polar, that will synchronise once its orbital period and mass transfer rate decrease sufficiently -in fact, for the parameters determined here, HS 0943+1404 lies above the synchronisation line in Fig. 4 of Norton et al (2004).…”

Section: The Intermediate Polar Nature Of Hs 0943+1404mentioning

confidence: 70%

HS 0943+1404, a true intermediate polar

Rodríguez‐Gil

Gänsicke²,

Hagen

et al. 2005

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Abstract.We have identified a new intermediate polar, HS 0943+1404, as part of our ongoing search for cataclysmic variables in the Hamburg Quasar Survey. The orbital and white dwarf spin periods determined from time-resolved photometry and spectroscopy are P orb 250 min and P spin = 69.171 ± 0.001 min, respectively. The combination of a large ratio P spin /P orb 0.3 and a long orbital period is very unusual compared to the other known intermediate polars. The magnetic moment of the white dwarf is estimated to be µ 1 ∼ 10 34 G cm 3 , which is in the typical range of polars. Our extensive photometry shows that HS 0943+1404 enters into deep (∼3 mag) low states, which are also a characteristic feature of polars. We therefore suggest that the system is a true "intermediate" polar that will eventually synchronise, that is, a transitional object between intermediate polars and polars. The optical spectrum of HS 0943+1404 also exhibits a number of unusual emission lines, most noticeably N II λ5680, which is likely to reflect enhanced nitrogen abundances in the envelope of the secondary.

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The Spin Periods and Magnetic Moments of White Dwarfs in Magnetic Cataclysmic Variables

Cited by 171 publications

References 51 publications

Confirmation of 1RXS J165443.5–191620 as an intermediate polar and its orbital and spin periods

Confirmation of 1RXS J165443.5–191620 as an intermediate polar and its orbital and spin periods

A precessing accretion disc in the intermediate polar XY Arietis?

HS 0943+1404, a true intermediate polar

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