[vsnet-alert 9519] V4641 Sgr : Activities in Infrared

[Akira Arai]

V4641 Sgr may be active in infrared now.

Plese see our blog "KANATA ObsLog & Temporary Results"
http://kanatatmp.blogspot.com/2007/08/v4641-sgr-activitis-in-infrared.html

We noticed that J-band excesses over the quiescent modulation this
week.Between JD245340 and JD245432 (last 3 points), in particular, the
infrared excess is large.
The J-band excess may indicate a "jet like" component or an cool
optically thick outflow. On JD245432, orbital phase is ~ 0(=inferior
conjunction of the black hole and the accretion disk) and V-band is
fainter than usual, but we can confirm a J-band excess relative to
V-band observation. At this point the secondary star might be obscured
by the jet or the cool outflow which covering the central region of the
accretion disk.

Regards,
Akira Arai and Makoto Uemura
Hiroshima Univ. Japan