Ultraviolet spectrophotometry and optical and infrared photometry of the old nova GK Persei

Wu, Chi-Chao; Holm, A. V.; Panek, R. J.; Raymond, J. C.; Hartmann, Lee; Swank, J. H.

doi:10.1086/167309

Cited by 27 publications

(32 citation statements)

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“…Bianchini & Sabbadin (1983) first showed that standard steady-state disk models could not reproduce UV observations of GK Per at minimum. Wu et al (1989) reached the same conclusions for outburst spectra. Both groups showed that disks with an inner hole could roughly match observed fluxes.…”

Section: The Observed Uv Spectrum and Simple Disk Models For Gk Persupporting

confidence: 69%

“…The UV spectrum of GK Per at maximum is very unusual compared to other dwarf novae in outburst (see also Wu et al 1989). The dereddened continuum is almost flat in F λ over 1200-3200Å and closely resembles the continuum of a B8-B9 V star with an effective temperature of 10,000-12,000 K (Wu et al 1989). In contrast, the UV continua of most dwarf novae at maximum resemble spectra of much hotter B2-B3 V-III stars having temperatures of ∼ 20,000 K (la Dous 1991).…”

Section: The Observed Uv Spectrum and Simple Disk Models For Gk Permentioning

confidence: 93%

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A Laboratory for Magnetized Accretion Disk Model: Ultraviolet and X‐Ray Emission from Cataclysmic Variable GK Persei

Kenyon

1997

ApJ

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We analyze the ultraviolet spectrum of the cataclysmic variable GK Per at maximum light. The flat ultraviolet spectrum in this system requires a truncated inner accretion disk and an unusually flat radial temperature profile. This requirement is not satisfied by any non-magnetic steady or non-steady disk model.We consider a magnetized accretion disk model to explain the ultraviolet spectrum. The available data on the white dwarf spin and possible quasi-periodic oscillations constrain the magnetic field, B * , and the disk accretion rate,Ṁ , to lie along a well-defined spin-equilibrium condition (Ṁ /10 17 g s −1 ) ∼ 100(B * /10 7 G) 2 . Our selfconsistent treatment of the magnetic torque on the disk flattens the disk temperature distribution outside the disk truncation radius. This modified temperature distribution is too steep to explain the UV spectrum for reasonable field strengths.X-ray heating is a plausible alternative to magnetic heating in GK Per. We estimate that the disk intercepts ∼ 5% of the accretion energy in outburst, which results in an extra disk luminosity of ∼ 5-10 L ⊙ . Model spectra of optically thick disks are too blue to match observations. The UV spectrum of an optically thick disk with an optically thin, X-ray heated corona resembles the observed spectrum. The X-ray luminosity observed during the outburst indicatesṀ < 10 18 g s −1 , which is a factor of 10 lower than that required to explain the ultraviolet luminosity. Radiation drag on material flowing inward along the accretion column lowers the shock temperature and reduces the X-ray luminosity. Most of the accretion energy is then radiated at extreme ultraviolet wavelengths.

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Section: The Observed Uv Spectrum and Simple Disk Models For Gk Persupporting

confidence: 69%

Section: The Observed Uv Spectrum and Simple Disk Models For Gk Permentioning

confidence: 93%

A Laboratory for Magnetized Accretion Disk Model: Ultraviolet and X‐Ray Emission from Cataclysmic Variable GK Persei

Kenyon

1997

ApJ

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“…Later, TI could spread over the whole disk as the further cooling WD brought the whole disk into a thermally unstable regime. Wu et al 1989). However, some problems remain.…”

Section: Discussionmentioning

confidence: 99%

“…Our analysis further revealed that the changes of the quiescent level are not correlated with variation of T C , m max or W . The disk is dim in quiescence, so the K-type secondary contributes significantly to the total luminosity (1/3 to 1/2: Wu et al 1989;Anupama & Prabhu 1993). The interpretation of the observed wave in terms of luminosity variations of the secondary is therefore reasonable because variations of the mean photospheric temperature by just a few hundreds of Kelvins, caused for example by a variable coverage by the dark (cool) spots are then sufficient to invoke changes of the system luminosity of the observed amplitude.…”

Section: Discussionmentioning

confidence: 99%

Dramatic change of the recurrence time and outburst parameters of the intermediate polar GK Persei

Šimon

2002

A&A

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Abstract. This analysis has shown that the intermediate polar GK Per experienced a very striking evolution. Its outbursts became wider and brighter in the last five decades. These changes were accompanied by striking variations of the recurrence time TC, from 385 days within the years 1948-1967 to 890 days in 1970. Nowadays, TC displays a strong trend of linear increase. Decrease of irradiation of the disk by the WD, combined with the decrease of viscosity, offers a plausible explanation. It is argued that variations of the mass transfer rate are unlikely to play a major role. The morphology of the outburst light curves in the optical and the X-ray region is also studied. The decay branch in the optical remains remarkably similar for all the events while the largest changes of the light curve occur in the rising branch. This can be explained if the thermal instability may start at different distances from the disk center. The quiescent level of brightness does not display any secular trend in recent decades but a wave on the time scale of about 30 years with the full amplitude of 0.3 mv, probably due to activity of the cool star, is detected.

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“…Hellier & Mukai claim that the red wing of the line in their Chandra data is due to the movement of the infalling material. Wu et al (1989) and Yi & Kenyon (1997) find a very flat UV spectrum (log Flux (erg cm −2 s −1 Å −1 ) ≈ −11.75 over the range 1000 to 3500 Å) which they explain with a truncated accretion disc. Since a magnetic model is not successful, they suggest X-ray heating.…”

Section: Introductionmentioning

confidence: 92%

On the nature of the X-ray source in GK Persei

Vrielmann

Ness

Schmitt

2005

A&A

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Abstract. We report XMM-Newton observations of the intermediate polar (IP) GK Per on the rise to the 2002 outburst and compare them to Chandra observations during quiescence. The asymmetric spin light curve implies an asymmetric shape of a semi-transparent accretion curtain and we propose a model for its shape. A low Fe  (λλ15.01/15.26 Å) line flux ratio confirms the need for an asymmetric geometry and significant effects of resonant line scattering. Medium resolution PN spectra in outburst and ACIS-S spectra in quiescence can both be fitted with a leaky absorber model for the post shock hard X-ray emission, a black body (outburst) for the thermalized X-ray emission from the white dwarf and an optically thin spectrum. The difference in the leaky absorber emission between high and low spin as well as quasi-periodic oscillation (QPO) or flares states can be fully explained by a variation in the absorbing column density. For the explanation of the difference between outburst and quiescence a combination of the variation of the column density and the electron and ion densities is necessary. The Fe fluorescence at 6.4 keV with an equivalent width of 447 eV and a possible Compton scattering contribution in the red wing of the line is not significantly variable during spin cycle or on QPO periods, i.e. a significant portion of the line originates in the wide accretion curtains. High-resolution RGS spectra reveal a number of emission lines from H-like and He-like elements. The lines are broader than the instrumental response with a roughly constant velocity dispersion for different lines, indicating identical origin. He-like emission lines are used to give values for the electron densities of log n e ∼ 12. We do not detect any variation in the emission lines during the spin cycle, implying that the lines are not noticeably obscured or absorbed. We conclude that they originate in the accretion curtains and that accretion might take place from all azimuths.

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Ultraviolet spectrophotometry and optical and infrared photometry of the old nova GK Persei

Cited by 27 publications

References 0 publications

A Laboratory for Magnetized Accretion Disk Model: Ultraviolet and X‐Ray Emission from Cataclysmic Variable GK Persei

A Laboratory for Magnetized Accretion Disk Model: Ultraviolet and X‐Ray Emission from Cataclysmic Variable GK Persei

Dramatic change of the recurrence time and outburst parameters of the intermediate polar GK Persei

On the nature of the X-ray source in GK Persei

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