Article

# Searching for flickering statistics in T CrB

(Impact Factor: 5.23). 11/2009; 402(4). DOI: 10.1111/j.1365-2966.2009.16068.x
Source: arXiv

ABSTRACT We analyze $V$-band photometry of the aperiodic variability in T CrB. By applying a simple idea of angular momentum transport in the accretion disc, we have developed a method to simulate the statistical distribution of flare durations with the assumption that the aperiodic variability is produced by turbulent elements in the disc. Both cumulative histograms with Kolmogorov-Smirnov tests, and power density spectra are used to compare the observed data and simulations. The input parameters of the model $R_{\rm in}$ and $\alpha$ are correlated on a certain interval and the most probable values are an inner disc radius of $R_{\rm in} \simeq 4 \times 10^9$ cm and a viscosity of $\alpha \simeq 0.9$. The disc is then weakly truncated. We find that the majority of turbulent events producing flickering activity are concentrated in the inner parts of the accretion disc. Comment: 9 pages, 10 figures, accepted for publication in MNRAS

0 Followers
·
101 Views
• Source
##### Article: Flickering study of nova like systems KR Aur and UU Aqr
[Hide abstract]
ABSTRACT: We present a study of the flickering activity in two nova like systems KR Aur and UU Aqr. We applied a statistical model of flickering simulations in accretion discs based on turbulent angular momentum transport between two adjacent rings with an exponential distribution of the turbulence dimension scale. The model is based on a steady state disc model which is satisfied in the case of hot ionized discs of nova like cataclysmic variables. Our model successfully fits the observed power density spectrum of KR Aur with the disc parameter alpha = 0.10 - 0.40 and an inner disc truncation radius in the range R_in = 0.88 - 1.67 x 10^9 cm. The exact values depend on the mass transfer rate in the sense that alpha decreases and R_in increases with mass transfer rate. In any case, the inner disc radius found for KR Aur is considerably smaller than in quiescent dwarf novae, as predicted by the disc instability model. On the other hand, our simulations fail to reproduce the power density spectrum of UU Aqr. A tantalizing explanation involves the possible presence of spiral waves, which are expected in UU Aqr, because of its low mass ratio, but not in KR Aur. In general our model predicts the observed concentration of flickering in the central disc. We explain this by the radial dependence of the angular momentum gradient.
Monthly Notices of the Royal Astronomical Society 11/2011; 420(3). DOI:10.1111/j.1365-2966.2011.20210.x · 5.23 Impact Factor
• Source
##### Article: Difference between the optical flickering colours of cataclysmic variables and symbiotic recurrent novae
[Hide abstract]
ABSTRACT: We performed simultaneous observations in 3 bands (UBV) of the flickering variability of the recurrent novae RS Oph and T CrB at quiescence. Using new and published data, we compare the colours of the flickering in cataclysmic variables and symbiotic recurrent novae. We find a difference between the colours of the flickering source in these two types of accreting white dwarfs. The detected difference is highly significant with $p-value \approx 2 \times 10^{-6}$ for the distributions of $(U-B)_0$ colour and $p \approx 3 \times 10^{-5}$ on (U-B) versus (B-V) diagram. The possible physical reasons are briefly discussed. The data are available upon request from the authors.
Astronomische Nachrichten 02/2015; 336(2). DOI:10.1002/asna.201412142 · 1.12 Impact Factor
• Source
##### Article: Resolving different sources of fast X-ray variability of the dwarf nova RU Peg in quiescence
[Hide abstract]
ABSTRACT: We analysed an X-ray light curve of the dwarf nova RU Peg taken by XMM-Newton with a duration of 46300 s. The power density spectrum has a complicated shape with two red noise and two white noise components, indicating the presence of two turbulent regions. We developed a statistical "toy model" to study light curves with variability produced by an unstable turbulent accretion flow from the inner disc. Our results are consistent with a disc truncation radius maximally 0.8 x 10^9 cm. We found that any fluctuation of the viscous mass accretion at the inner disc are visible as UV and X-ray variations with the same break frequency in the power density spectrum. This process is generating low frequency variability. A second break suggests the presence of a faster X-ray variability component which must be generated by another process likely localised between the inner disc and the white dwarf.
Monthly Notices of the Royal Astronomical Society 11/2013; 438(2). DOI:10.1093/mnras/stt2311 · 5.23 Impact Factor