Central Bureau for Astronomical Telegrams
IAUC 7672: WZ Sge
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Circular No. 7672
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
CBAT@CFA.HARVARD.EDU (science)
URL http://cfa-www.harvard.edu/iau/cbat.html ISSN 0081-0304
Phone 617-495-7440/7244/7444 (for emergency use only)
WZ SAGITTAE
T. Kato, R. Ishioka, M. Uemura, K. Matsumoto, and H. Ohashi,
Kyoto University; G. Masi, Ceccano, Italy; G. A. Good, Albuquerque,
NM; J. Pietz, Erftstadt, Germany; and M. Moilanen, Nyrola
Observatory, on behalf of the VSNET collaboration team, write: "Our
time-resolved CCD photometry reveals that WZ Sge started to show
prominent, highly structured oscillations (amplitude 0.45-0.50 mag)
on July 23.76 UT. The oscillations have had a stable period of
0.056652 +/- 0.000006 day between July 24.46 and 27.01, which is in
striking agreement with the orbital period (0.05669 day) of WZ Sge.
This finding confirms the development of 'early superhumps', as
predicted by Ishioka et al. (IAUC 7669). For more details of the
evolution of early superhumps, see
http://www.kusastro.kyoto-u.ac.jp/vsnet/DNe/wzsge01.html."
H. Baba, National Astronomical Observatory of Japan; K.
Sadakane, Osaka-Kyoiku University; and Y. Norimoto, Okayama
Astrophysical Observatory (OAO), communicate: "We made time-
resolved spectroscopic observations (range 400-500 nm) of WZ Sge
between July 24.576 and 24.701 UT with the OAO 0.91-m telescope.
Spectra taken at about the middle of the eclipses show that He II
468.6-nm is strongly in emission with a double-peaked profile. The
estimated peak separation is about 1.4 nm, but the profile of the
peaks varies with the orbital period. The C III-N III complex at
464.0 nm is also in double-peaked emission. These variations may
indicate an actual evolutionary effect during the early stage of
the outburst. On the other hand, H-beta shows both emission and
absorption features like a P-Cyg profile, varying with the orbital
period. Higher Balmer series H-gamma and H-delta are seen as broad
absorption features, as is He I 447.1-nm. The emission-line
features resemble the beginning of the 1978 outburst (cf. IAUC
3311; Ortolani et al. 1980, A.Ap. 87, 31) taken four days after
maximum, but they does not resemble those in the spectra taken by
K. Ayani at Bisei during the rising stage (IAUC 7669), which shows
no emission component around the wavelengths of He II and the C-N
complex."
Corrigendum. On IAUC 7669, line 18, FOR Oltorani et al.
1980, READ Ortolani et al. 1980,
Visual magnitude estimates: July 24.923 UT, 8.7 (R. Bouma,
Groningen, The Netherlands); 24.96, 8.0 (E. Broens, Mol, Belgium);
25.094, 8.6 (P. Schmeer, Bischmisheim, Germany); 25.573, 8.3 (A.
Pearce, Nedlands, W. Australia); 25.956, 8.4 (H. Bengtsson, Hisigs
Backa, Sweden); 25.986, 8.7 (Bouma); 26.885, 8.7 (A. Kammerer,
Ettlingen, Germany).
(C) Copyright 2001 CBAT
2001 July 27 (7672) Daniel W. E. Green
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