Optical flares on the RS CVn binary II Peg

Mathioudakis, M.; Doyle, J. G.; Avgoloupis, S.; Mavridis, L. N.; Seiradakis, J. H.

doi:10.1093/mnras/255.1.48

Cited by 22 publications

(23 citation statements)

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“…Henry & Newsom (1996) estimated a flaring rate of one flare per 4.45 h, what agrees well with the Mathioudakis et al (1992) result. They noted that Byrne et al (1994) monitored II Peg in 1992 in a U filter and found no optical flares.…”

Section: Flaressupporting

confidence: 78%

“…Mathioudakis et al (1992) detected 10 flares during 57.4 h of optical monitoring in the Johnson U and B filters, finding the rate of one flare per 5.9 h.…”

Section: Flaresmentioning

confidence: 98%

“… Bopp & Noah (1980a) observed sudden Hα enhancements which slowly decayed on time‐scales of days. Doyle et al (1991) simultaneously detected a flare in X‐rays and the Johnson U filter – the latter had a duration of more than 36 min. Mathioudakis et al (1992) detected 10 flares during 57.4 h of optical monitoring in the Johnson U and B filters, finding the rate of one flare per 5.9 h. Doyle et al (1993) observed two flares in their ultraviolet spectra, with one lasting about 3 h. The same work reported three optical flares, lasting 10.52, 101.00 and 9.08 min, with amplitudes 0.066 mag ( B band), 0.371 mag ( U band) and 0.207 mag ( U band), respectively. Mohin & Raveendran (1993) found one flare in their optical spectra; they summarized the results obtained by other authors and concluded that II Peg shows a tendency to flare mainly when close to its minimum light. Henry & Newsom (1996) estimated a flaring rate of one flare per 4.45 h, what agrees well with the Mathioudakis et al (1992) result. They noted that Byrne et al (1994) monitored II Peg in 1992 in a U filter and found no optical flares.…”

Section: Flaresmentioning

confidence: 99%

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Analysis of the MOST light curve of the heavily spotted K2IV component of the single-line spectroscopic binary II Pegasi★

Siwak

Ruciński

Matthews

et al. 2010

Monthly Notices of the Royal Astronomical Society

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Continuous photometric observations of the visible component of the single‐line, K2IV spectroscopic binary II Peg carried out by the MOST satellite during 31 consecutive days in 2008 have been analysed. On top of spot‐induced brightness modulation, 11 flares were detected of three distinct types characterized by different values of rise, decay and duration times. The flares showed a preference for occurrence at rotation phases when the most spotted hemisphere is directed to the observer, confirming previous similar reports. An attempt to detect a grazing primary minimum caused by the secondary component transiting in front of the visible star gave a negative result. The brightness variability caused by spots has been interpreted within a cold spot model. An assumption of differential rotation of the primary component gave a better fit to the light curve than a solid‐body rotation model.

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Section: Flaressupporting

confidence: 78%

“…Mathioudakis et al (1992) detected 10 flares during 57.4 h of optical monitoring in the Johnson U and B filters, finding the rate of one flare per 5.9 h.…”

Section: Flaresmentioning

confidence: 98%

Section: Flaresmentioning

confidence: 99%

See 1 more Smart Citation

Analysis of the MOST light curve of the heavily spotted K2IV component of the single-line spectroscopic binary II Pegasi★

Siwak

Ruciński

Matthews

et al. 2010

Monthly Notices of the Royal Astronomical Society

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“…We can now draw a comparison between V404 Cyg and II Peg, an RS CVn with similar orbital period (P orb ¼ 6:72 days) and spectral type companion (K2 IV-V). Ten flares have been detected in II Peg in the Johnson U and B bands, with absolute energies in the range ð1 180Þ Â 10 33 ergs (Mathioudakis et al 1992). The reported time-averaged flare luminosity is $1:9 Â 10 30 ergs s À1 in the U band.…”

Section: Chromospheric Emissionmentioning

confidence: 99%

Evidence for Optical Flares in Quiescent Soft X‐Ray Transients

Zurita

Casares

Shahbaz

2003

ApJ

120

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We present the results of high time resolution optical photometry of five quiescent soft X-ray transients (SXTs): V404 Cyg, A0620À00, J0422+32, GS 2000+25, and Cen X-4. We detect fast optical variations superposed on the secondary star's double-humped ellipsoidal modulation. The variability resembles typical flare activity and has amplitudes ranging from 0.06 to 0.6 mag. Flares occur on timescales of minutes to a few hours, with no dependency on orbital phase, and contribute $19%-46% to the total veiling observed in the R band. We find that the observed level of flaring activity is veiled by the light of the companion star, and therefore, systems with cool companions (e.g., J0422+32) exhibit stronger variability. After correcting for this dilution, we do not find any correlation between the flaring activity and fundamental system parameters. We find no underlying coherent periods in the data, only quasi-periodic variations ranging between 30 and 90 minutes for the short-period SXTs and longer than 1 hr for V404 Cyg. The power-law index of the power spectra is consistent with what is observed at X-rays wavelengths, i.e., a 1/f distribution, which is compatible with the cellular automaton model. Our observed R 0 -band luminosities, which are in the range 10 31 -10 33 ergs s À1 , are too large to be due to chromospheric activity in the rapidly rotating companions. Since the typical timescale of the flares increases with orbital period, they are most likely produced in the accretion disk. The associated dynamical (Keplerian) timescales suggest that flares are produced at $0.3R d -0.7R d . Possible formation mechanisms are magnetic loop reconnection events in the disk or, less likely, optical reprocessing of X-ray flares. In the former scenario, the maximum duration of the flares suggests that the outer disk is responsible for the flare events and so allows us to constrain the sharing timescale to $ 5 6 ð Þ À1 K .

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“…However, the frequency of optical flares is a matter of current debate. Two recent optical studies of the RS CVn star II Peg, appear to be in serious disagreement (Mathioudakis et al 1992, Byrne et al 1994. The former claims a rate of optical flaring in agreement with the rate of ultraviolet flares seen with the IUE satellite (see below), while the other failed to record any flares in a total observing time about 5 times the mean interval between ultraviolet flares.…”

Section: Opticalmentioning

confidence: 89%

Flares: the Solar-Stellar Connection

Byrne¹

1995

International Astronomical Union Colloquium

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The systematic study of stellar flares in now more than 30 years old. Throughout that time the solar flare paradigm has been used, highly successfully, to understand various aspects of the stellar phenomenon. In this introductory overview I will attempt to justify the use of the solar model in understanding the stellar equivalent. But I will also point out differences between the two which may require extension of the basic solar model and speculate briefly on what these extensions might be.There are many excellent previous reviews of stellar flares in the literature (Haisch 1989, Byrne 1983, 1992), to which the reader is referred, along with the other reviews in this volume, for further reading.

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Optical flares on the RS CVn binary II Peg

Cited by 22 publications

References 0 publications

Analysis of the MOST light curve of the heavily spotted K2IV component of the single-line spectroscopic binary II Pegasi★

Analysis of the MOST light curve of the heavily spotted K2IV component of the single-line spectroscopic binary II Pegasi★

Evidence for Optical Flares in Quiescent Soft X‐Ray Transients

Flares: the Solar-Stellar Connection

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