[vsnet-campaign-xray 363] V4641 Sgr: returned to quiescence(?)

[Makoto Uemura]

V4641 Sgr: returned to quiescence(?)

    K. Nakajima kindly sent us a new time-series data of V4641 Sgr 
taken on July 12.  The light curve is completely on the quiescent 
ellipsoidal modulation.  The last active state apparently 
finished, at least in the optical range (in the optical wavelengths, 
the emission from the mass donor star is dominant).   

    V4641 Sgr had kept slightly (~0.1mag) brighter than the quiescence 
after the outburst.  We could frequently see short flares during 
this phase.  This post-outburst active phase was observed from 27 June 
to 6 July.  And it had already been terminated on 12 July. 

    Characteristics of the 2005 outburst are, in general, similar 
to those in 2002, 2003, and 2004.  The durations of the outbursts are, 
however, apparently decreasing year by year.  It is possible that 
we just overlooked early phases of the outbursts.  

    During the 2005 outburst, we got many samples of short flares or 
flashes more than those in 2002-2004.  We will analyze all data sets 
of 2002-2005.  The object might become active again even during this year. 
Close monitorings and time-series observations are encouraged.

Regards,
Makoto Uemura
Hiroshima University