[vsnet-alert 9297] Re: GW Lib outburstspell < vs.mai

[Taichi Kato]

> S. Narusawa, and H. Naito started spectroscopic observations
> of GW Lib by the 2-m NAYUTA telescope and a low dispersion
> spectrograph MALLS at Nishi-Harima Astronomical Observatory
> for about 4 hours from Apr. 13.6 (UT), well before the maximum.
> The spectra are still under reduction, but the quick look
> images showed prominent absorption lines of the Balmer series.
> These features are in contrast with those in the spectra
> (doubly-peaked Balmer lines, He I&II lines and so on) of
> WZ Sge obtained before the maximum of the 2001 superoutburst
> of WZ Sge (see Baba et al. 2002, PASJ, 54, L7;
> http://jp.arxiv.org/abs/astro-ph/0112374), which may be
> due to the difference of the inclination?

   If He II emission arises later on, the present finding may
suggest that the heating front hadn't yet reached the inner
accretion disk - i.e. the outburst is "outside-in".

   Time-resolved spectroscopy rather than nightly snapshots
is recommend if rapid change in the spectrum is observed.