Time-Resolved Photometry of GK Persei during the 1996 Outburst

Nogami, Daisaku; Katô, Takeo; Baba, Hajime

doi:10.1093/pasj/54.6.987

Cited by 15 publications

(18 citation statements)

References 80 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The presence of the spin modulation observed in the X-ray band during previous outbursts of GK Per (e.g., Hellier et al 2004;Evans et al 2009) suggested accretion onto the magnetic poles of the WD. In addition to the modulation with P spin , GK Per also displayed a modulation with the cycle length P M of about 4000−5000 s in the X-ray (Watson et al 1985;Hellier & Livio 1994;Hellier et al 2004) and the optical bands (e.g., Mazeh et al 1985;Morales-Rueda et al 1999;Nogami et al 2002). Two interpretations exist.…”

Section: Discussionmentioning

confidence: 92%

“…Figure 4 shows the result. The frequency range over which the intensity variations were searched for is similar to range used by Nogami et al (2002). I found that the modulation with the cycle length of about 4000-5000 s is present in most night series in Fig.…”

Section: Discussionmentioning

confidence: 93%

“…Several observations that deviated widely from the neighboring points in the light curve were rejected. During the outburst, GK Per displays quasiperiodic variations on the timescale of minutes and tens of minutes, with the peakto-peak amplitude of several tenths of mag (e.g., Mazeh et al 1985;Nogami et al 2002). Because this analysis concentrates on the evolution of the outbursts on timescales of days and tens of days, I emphasized the profile of the outburst by binning the observations into one-day means.…”

Section: Discussionmentioning

confidence: 99%

See 2 more Smart Citations

The intermediate polar GK Persei: An unstable relation of the X-ray and the optical intensities in a series of outbursts

Šimon

2015

A&A

View full text Add to dashboard Cite

Context. GK Per is an intermediate polar that has been displaying dwarf nova outbursts since the middle of the twentieth century. Aims. I analyzed a series of such outbursts in the optical and X-ray bands. I pay attention to the relation of intensities of the optical and X-ray emissions, and its reproducibility in a series of these consecutive outbursts.Methods. This analysis uses the data from the BAT/Swift, ASM/RXTE, AAVSO, and AFOEV databases. It investigates the relation of the time evolution of the profiles of outbursts in the individual bands (hard X-ray, medium/hard X-ray, and optical).Results. This analysis shows that the X-ray intensity steeply rises only in the start of the optical outburst and steeply declines only when the optical outburst comes to its end. However, the 1.5-50 keV band intensity saturates and balances on a plateau during the outburst. (The longer the outburst, the longer its plateau.) The peak X-ray intensities of this series display a significantly narrower range than the optical ones (a factor of about two versus a factor of about eight). This implies a discrepancy between the mass flow through the disk and the production of the X-ray emission via bremsstrahlung at the polar caps of the white dwarf. This discrepancy is the largest in the time of the peak optical intensity when the whole disk (or at least its inner part) is in the hot state and the flow of matter through the disk is the greatest. This study shows that a series of outbursts constitutes more general properties of this discrepancy. I argue that the saturation of the X-ray luminosity in outburst cannot be caused by a dominant increase in X-ray absorption. In the interpretation, large structural changes of the accreting regions at the magnetic poles of the white dwarf occur during the outburst. A buried shock proposed by some authors for polars is also promising for explaining the X-ray light curves of outbursts of GK Per.

show abstract

Section: Discussionmentioning

confidence: 92%

Section: Discussionmentioning

confidence: 93%

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

The intermediate polar GK Persei: An unstable relation of the X-ray and the optical intensities in a series of outbursts

Šimon

2015

A&A

View full text Add to dashboard Cite

show abstract

“…Previously, Watson et al (1985) reported a modulation of their EXOSAT (1.5−8.5 keV) data on a time scale of 2000 to 10 000 s. Subsequently, these QPOs have been observed also in the optical continuum (Morales Rueda et al 1999;Nogami et al 2002) and in the X-ray band by ASCA (0.7−10 keV, Ishida et al 1996).…”

Section: Introductionmentioning

confidence: 93%

“…The slow rise to maximum light is probably caused by an inside-out outburst (Nogami et al 2002) -in contrast to a more usual outside-in outburst -or a more complicated scenario, where the outburst starts at different distances from the disc centre (Šimon 2002).…”

Section: Introductionmentioning

confidence: 96%

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

Vrielmann

Ness

Schmitt

2005

A&A

View full text Add to dashboard Cite

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.

show abstract

Dwarf nova oscillations and quasi-periodic oscillations in cataclysmic variables - III. A new kind of dwarf nova oscillation, and further examples of the similarities to X-ray binaries

Warner¹,

Woudt²,

Pretorius³

2003

Monthly Notices RAS

106

View full text Add to dashboard Cite

We present measurements of the periods of dwarf nova oscillations (DNOs) and quasi‐periodic oscillations (QPOs) in cataclysmic variable stars (CVs), many culled from published literature, but also others newly observed (in VZ Pyx, CR Boo, OY Car, Z Cha, AQ Eri, TU Men, HX Peg, CN Ori, V893 Sco, WX Hyi and EC2117−54). These provide data for 26 systems. We show that in general PQPO∼ 15 PDNO and that the correlation for CVs extends by three orders of magnitude lower in frequency the similar relationship found for X‐ray binaries. In addition, we have found that there is a second type of DNO, previously overlooked, which have periods ∼4 times those of the regular DNOs (as well as those mined from publications, we have observed them in VW Hyi, OY Car, AQ Eri, V803 Cen, CR Boo, VZ Pyx, HX Peg and EC2117−54). Often both types of DNO coexist. Unlike the standard DNOs, the periods of the new type, which we refer to as longer‐period DNOs (lpDNOs), are relatively insensitive to accretion luminosity and can even appear in quiescence of dwarf novae. We interpret them as magnetically channelled accretion on to the differentially rotating main body of the white dwarf primary, rather than on to a rapidly slipping equatorial belt as in the case of the standard DNOs. This is supported by published measurements of v sin i for some of the primaries. Some similarities of the DNOs, lpDNOs and QPOs in CVs to the three types of QPO in X‐ray binaries (burst pulsations, high‐ and low‐frequency QPOs) are noted.

show abstract

Time-Resolved Photometry of GK Persei during the 1996 Outburst

Cited by 15 publications

References 80 publications

The intermediate polar GK Persei: An unstable relation of the X-ray and the optical intensities in a series of outbursts

The intermediate polar GK Persei: An unstable relation of the X-ray and the optical intensities in a series of outbursts

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

Dwarf nova oscillations and quasi-periodic oscillations in cataclysmic variables - III. A new kind of dwarf nova oscillation, and further examples of the similarities to X-ray binaries

Contact Info

Product

Resources

About