Observations of quasi-periodic oscillations in the light curve of VW Hydri

1984 ◽  
Vol 277 ◽  
pp. 250 ◽  
Author(s):  
E. L. Robinson ◽  
B. Warner
Keyword(s):  
Light Curve ◽  
Periodic Oscillations

scholarly journals Quasi-Periodic and Periodic Oscillations in the Dwarf Nova AH Her

1979 ◽  
Vol 53 ◽  
pp. 403-403
Author(s):  
J.G. Duthie ◽  
R.S. McMillan
Keyword(s):  
Light Curve ◽  
Autocorrelation Function ◽  
High Speed ◽  
Statistical Significance ◽  
Cataclysmic Variables ◽  
Power Spectra ◽  
Photometric System ◽  
Periodic Oscillations ◽  
Dwarf Nova ◽  
High Statistical Significance

With a high speed photometric system we have made extensive observation of the dwarf nova AH Her. We have detected rapid oscillations on two consecutive nights during the recovery portion of the light curve of a typical outburst during the spring of 1979. The periods and the sense of the change of period are consistent with previous observations of rapid oscillations of AH Her. On another occasion we detected quasi-periodic oscillations during the rising portion of an outburst. These are similar in appearance to quasi-periodic oscillations found in other cataclysmic variables in that they appear with high statistical significance in the autocorrelation function but are not apparent in power spectra (Robinson and Nather 1979). However they are different from those reported by Robinson and Nather in the sense that they have the same order of period as the periodic rapid oscillations typical of AH Her. These results will be presented together with a discussion of their Implications.

scholarly journals Probing the X-ray Variability of X-ray Binaries

2003 ◽  
Vol 214 ◽  
pp. 236-239
Author(s):  
Wenfei Yu
Keyword(s):  
Neutron Star ◽  
Light Curve ◽  
Time Scale ◽  
Accretion Rate ◽  
Power Spectra ◽  
The Other ◽  
Periodic Oscillations ◽  
X Ray ◽  
Orbital Frequency ◽  
X Ray Binaries

Kilohertz quasi-periodic oscillations (kHz QPOs) has been regarded as representing the Keplerian frequency at the inner disk edge in the neutron star X-ray binaries. The so-called “parallel tracks” on the plot of the kHz QPO frequency vs. X-ray flux in neutron star X-ray binaries, on the other hand, show the correlation between the kHz QPO frequency and the X-ray flux on time scales from hours to days. This is suspected as caused by the variations of the mass accretion rate through the accretion disk surrounding the neutron star. We show here that by comparing the correlation between the kHz QPO frequency and the X-ray count rate on a certain QPO time scale observed approximately simultaneous in the Fourier power spectra of the X-ray light curve, we have found evidences that the X-ray flux of millihertz QPOs in neutron star X-ray binaries is generated inside the inner disk edge if adopting that the kilohertz QPO frequency is an orbital frequency at the inner disk edge.

Detection of superhumps and quasi-periodic oscillations in the light curve of the dwarf nova SW Ursae Majoris

1987 ◽  
Vol 313 ◽  
pp. 772 ◽  
Author(s):  
Edward L. Robinson ◽  
Allen W. Shafter ◽  
J. Allen Hill ◽  
Matt A. Wood ◽  
Janet A. Mattei
Keyword(s):  
Light Curve ◽  
Periodic Oscillations ◽  
Dwarf Nova

scholarly journals QUASI-PERIODIC OSCILLATIONS OF ∼15 MINUTES IN THE OPTICAL LIGHT CURVE OF THE BL LAC S5 0716+714

2010 ◽  
Vol 719 (2) ◽  
pp. L153-L157 ◽  
Author(s):  
Bindu Rani ◽  
Alok C. Gupta ◽  
U. C. Joshi ◽  
S. Ganesh ◽  
Paul J. Wiita
Keyword(s):  
Light Curve ◽  
Periodic Oscillations ◽  
Bl Lac ◽  
Optical Light Curve

scholarly journals DETECTION OF POSSIBLE QUASI-PERIODIC OSCILLATIONS IN THE LONG-TERM OPTICAL LIGHT CURVE OF THE BL LAC OBJECT OJ 287

2016 ◽  
Vol 832 (1) ◽  
pp. 47 ◽  
Author(s):  
G. Bhatta ◽  
S. Zola ◽  
Ł. Stawarz ◽  
M. Ostrowski ◽  
M. Winiarski ◽  
...  
Keyword(s):  
Light Curve ◽  
Periodic Oscillations ◽  
Bl Lac ◽  
Optical Light Curve

scholarly journals Multi-waveband quasi-periodic oscillations in the light curves of blazar CTA 102 during its 2016–2017 optical outburst

2020 ◽  
Vol 642 ◽  
pp. A129
Author(s):  
Arkadipta Sarkar ◽  
Pankaj Kushwaha ◽  
Alok C. Gupta ◽  
Varsha R. Chitnis ◽  
Paul J. Wiita
Keyword(s):  
Light Curve ◽  
Moving Average ◽  
Autoregressive Process ◽  
Light Curves ◽  
Significant Activity ◽  
Periodic Oscillations ◽  
Monte Carlo Techniques ◽  
Spectrum Radio ◽  
Flux Modulation ◽  
Dominant Period

Context. Quasi-periodic fluctuations in the light curves of blazars can provide insight into the underlying emission process. This type of flux modulation hints at periodic physical processes that result in emission. CTA 102, a flat spectrum radio quasar at a redshift of 1.032, has displayed significant activity since 2016. The multi-waveband light curve of CTA 102 shows signs of quasi-periodic oscillations during the 2016–2017 flare. Aims. Our goal is to rigorously quantify the presence of any possible periodicity in the emitted flux during the mentioned period and to explore the possible causes that can give rise to it. Methods. Techniques such as the Lomb-Scargle periodogram and weighted wavelet z-transform were employed to observe the power emitted at different frequencies. To quantify the significance of the dominant period, Monte-Carlo techniques were employed to consider an underlying smooth bending power-law model for the power spectrum. In addition, the light curve was modeled using an autoregressive process (AR1) to analytically obtain the significance of the dominant period. Lastly, the light curve was modeled using a generalized autoregressive integrated moving average (ARIMA) process to check whether introducing a seasonal (periodic) component results in a statistically preferable model. Results. Highly significant, simultaneous quasi-periodic oscillations (QPOs) were observed in the γ-ray and optical fluxes of blazar CTA 102 during its highest optical activity episode in 2016–2017. The periodic flux modulation had a dominant period of ∼7.6 days and lasted for ∼8 cycles (MJD 57710–57770). All of the methods used point toward significant (> 4σ) quasi-periodic modulation in both γ-ray and optical fluxes. Conclusions. Several possible models were explored while probing the origin of the periodicity, and by extension, the 2016–2017 optical flare. The best explanation for the detected QPO appears to be a region of enhanced emission (blob), moving helically inside the jet.

scholarly journals Insights into the inner regions of the FU Orionis disc

2018 ◽  
Vol 618 ◽  
pp. A79 ◽  
Author(s):  
Michał Siwak ◽  
Maciej Winiarski ◽  
Waldemar Ogłoza ◽  
Marek Dróżdż ◽  
Stanisław Zoła ◽  
...  
Keyword(s):  
Light Curve ◽  
Spectral Range ◽  
Small Amplitude ◽  
Winter Season ◽  
Stellar Mass ◽  
Periodic Oscillations ◽  
Clear Sign ◽  
Fu Ori ◽  
Periodic Family ◽  
Visual Light

Context. We investigate small-amplitude light variations in FU Ori occurring in timescales of days and weeks. Aims. We seek to determine the mechanisms that lead to these light changes. Methods. The visual light curve of FU Ori gathered by the MOST satellite continuously for 55 d in the 2013–2014 winter season and simultaneously obtained ground-based multi-colour data were compared with the results from a disc and star light synthesis model. Results. Hotspots on the star are not responsible for the majority of observed light variations. Instead, we found that the long periodic family of 10.5–11.4 d (presumably) quasi-periods showing light variations up to 0.07 mag may arise owing to the rotational revolution of disc inhomogeneities located between 16 and 20 R⊙. The same distance is obtained by assuming that these light variations arise because of a purely Keplerian revolution of these inhomogeneities for a stellar mass of 0.7 M⊙. The short-periodic (∼3 – 1.38 d) small amplitude (∼0.01 mag) light variations show a clear sign of period shortening, similar to what was discovered in the first MOST observations of FU Ori. Our data indicate that these short-periodic oscillations may arise because of changing visibility of plasma tongues (not included in our model), revolving in the magnetospheric gap and/or likely related hotspots as well. Conclusions. Results obtained for the long-periodic 10–11 d family of light variations appear to be roughly in line with the colour-period relation, which assumes that longer periods are produced by more external and cooler parts of the disc. Coordinated observations in a broad spectral range are still necessary to fully understand the nature of the short-periodic 1–3 d family of light variations and their period changes.

scholarly journals Quasi-periodic Oscillations in the TESS Light Curve of TX Col, a Diskless Intermediate Polar on the Precipice of Forming an Accretion Disk

2021 ◽  
Vol 162 (2) ◽  
pp. 49
Author(s):  
Colin Littlefield ◽  
Simone Scaringi ◽  
Peter Garnavich ◽  
Paula Szkody ◽  
Mark R. Kennedy ◽  
...  
Keyword(s):  
Light Curve ◽  
Accretion Disk ◽  
Periodic Oscillations

Quasi-Periodic Oscillations in Dwarf Novae

1979 ◽  
Vol 46 ◽  
pp. 77-88
Author(s):  
Edward L. Robinson
Keyword(s):  
Binary Systems ◽  
Outer Edge ◽  
Light Curves ◽  
Close Binary ◽  
Bright Spot ◽  
Dwarf Novae ◽  
Periodic Oscillations ◽  
High Frequencies ◽  
Short Period ◽  
Typical Time

Three distinct kinds of rapid variations have been detected in the light curves of dwarf novae: rapid flickering, short period coherent oscillations, and quasi-periodic oscillations. The rapid flickering is seen in the light curves of most, if not all, dwarf novae, and is especially apparent during minimum light between eruptions. The flickering has a typical time scale of a few minutes or less and a typical amplitude of about .1 mag. The flickering is completely random and unpredictable; the power spectrum of flickering shows only a slow decrease from low to high frequencies. The observations of U Gem by Warner and Nather (1971) showed conclusively that most of the flickering is produced by variations in the luminosity of the bright spot near the outer edge of the accretion disk around the white dwarf in these close binary systems.

Sign in / Sign up

Export Citation Format

Share Document