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Featured paper:

Michael Ting-Chang Yang, Yi Chou, Chow-Choong Ngeow, Chin-Ping Hu, Yi-Hao Su, Thomas A. Prince, Shrinivas R. Kulkarni, David Levitan, Russ Laher, Jason Surace,Andrew J. Drake, Stanislav G. Djorgovski, Ashish A. Mahabal, Matthew J. Graham, Ciro Donalek

A systematic study on the long-term periodicities of known Galactic cataclysmic variables (CVs) was conducted. Among 1580 known CVs, 344 sources were matched and extracted from the Palomar Transient Factory (PTF) data repository. The PTF light curves were combined with the Catalina Real-Time Transient Survey (CRTS) light curves and analyzed. Ten targets were found to exhibit long-term periodic variability, which is not frequently observed in the CV systems. These long-term variations are possibly caused by various mechanisms, such as the precession of the accretion disk, hierarchical triple star system, magnetic field change of the companion star, and other possible mechanisms. We discuss the possible mechanisms in this study. If the long-term period is less than several tens of days, the disk precession period scenario is favored. However, the hierarchical triple star system or the variations in magnetic field strengths are most likely the predominant mechanisms for longer periods.


It’s all about the  standstills, those episodes where the star gets stuck at a mid-point between maximum and minimum. If it doesn’t exhibit standstills it isn’t a Z Cam star.









AM Her stars in need of further investigation







Data from Catalina Real Time Survey 
Drake et al. 2009, ApJ, 696, 87

Northern CVs brighter than 17th magnitude here.

Southern CV's brighter than 17th magnitude here.



ACTIVITY AT A GLANCE

New outbursts and unusual activity reported in the last 72 hours

Last updated 16:20 UT June 26, 2017

YYYYMMDD

20170626
PQ Aql
V1047 Aql
V1258 Cen
WX Hyi
TU Ind
BR Lup
RY Ser
V1089 Sgr
V2276 Sgr
V3774 Sgr
VW Tuc
SW Vol

20170625
CY Lyr



# indicates a noteworthy or unusual outburst
:  indicates confirmation required
 
'Activity At A Glance' is gleaned from observations reported to AAVSO MyNewsFlash, BAAVSS-Alert, CVnet-Outburst, VSObs-share and VSNET-outburst. We sincerely thank all the observers who contribute timely observations and reports of activity to these email lists.

RECENT PAPERS ON CVs


For new papers on CV's see arxiv.org astro-ph

J.M Hameury & J.P Lasota

V. V. Lukin, K. L. Malanchev, N. I. Shakura, K. A. Postnov, V. M. Chechetkin, V. P. Utrobin



Authors: A. F. Pala, B. T. Gänsicke, D. Townsley, D. Boyd, M. J. Cook, D. De Martino, P. Godon, J. B. Haislip, A. A. Henden, I. Hubeny, K. M. Ivarsen, S. Kafka, C. Knigge, A. P. LaCluyze, K. S. Long, T. R. Marsh, B. Monard, J. P. Moore, G. Myers, P. Nelson, D. Nogami, R. Pickard, G. Poyner, D. E. Reichart, D. Rodriguez Perez, M. R. Schreiber, J. Shears, E. M. Sion, R. Stubbings, P. Szkody, M. Zorotovic


Liam K Hardy, Martin J McAllister, Vik S Dhillon, Stuart P Littlefair, Madelon C P Bours, Elme Breedt, Tim Butterley, Anurak Chakpor, Puji Irawati, Paul Kerry, Tom R Marsh, Steven G Parsons, Chris D J Savoury, Richard W Wilson, Patrick A Woudt


Authors: T. Muñoz-Darias, J. Casares, D. Mata Sánchez, R. P. Fender, M. Armas Padilla, K. Mooley, L. Hardy, P. A. Charles, G. Ponti, S. E. Motta, V. S. Dhillon, P. Gandhi, F. Jiménez-Ibarra, T. Butterley, S. Carey, K. J. B. Grainge, J. Hickish, S. P. Littlefair, Y. C. Perrott, N. Razavi-Ghods, C. Rumsey, A. M. M. Scaife, P. F. Scott, D. J. Titterington, R. W. Wilson


Authors: Rod Stubbings, Mike Simonsen

Spiral structures and temperature distribution in the quiescent accretion disc of the cataclysmic binary V2051 Ophiuchi

Authors: Artur Rutkowski, Waclaw Waniak, George W. Preston, Wojciech Pych


Authors: Andrey Semena, Mikhail Revnivtsev, David Buckley, Alexander Lutovinov, Hannes Breytenbach


Authors:  T. Kato et al


Authors: T.V. Tomov, K.A. Stoyanov, R.K. Zamanov