[IAUC] CBET 999: 20070713 : V919 SAGITTARII

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                                                  Electronic Telegram No. 999
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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V919 SAGITTARII
     U. Munari, A. Siviero, and H. Navasardyan, Istituto Nazionale di
Astrofisica, Padova Astronomical Observatory; and F. Castellani, M.
Bortolotti, P. Valisa, and V. Luppi, ANS ("Asiago Novae and Symbiotic
stars") collaboration, report that the symbiotic star V919 Sgr is currently
undergoing a strong outburst.  Measured magnitudes:  July 11.41 UT, B =
11.873, B-V = +0.681, V-R_c = +0.705, V-I_c = +1.621; July 12.40, B =
11.866, B-V = +0.677, V-R_c = +0.697, V-I_c = +1.611.  The corresponding
mean values during quiescence were B = 14.15, B-V = +1.22, V-I_c = +2.80.
Therefore the star rose by 2.3 mag in the B band and became much bluer.
Various low- and high-resolution, absolutely fluxed optical spectra of V919
Sgr have been obtained around July 12.9 with the 1.82-m telescope at Asiago
and the 0.6-m telescope of the Schiapparelli Observatory in Varese.
Compared with quiescence spectra, the He II 468.6-nm emission line has
disappeared, and the intensity of [O III] 500.7-nm is reduced.  The
remaining lines in emission are the Balmer series and He I.  The integrated
flux of H_alpha, H_beta, and He I 587.6-nm emission lines are 1.6 x
10**(-11), 2.0 x 10**(-12), and 6.3 x 10**(-13) erg cm**(-2) s**(-1),
respectively.  The H_alpha emission line profile does not show a P-Cyg
absorption component and it is characterized by a central reversal with a
FWHM of 105 km/s, blueshifted by 95 km/s with respect to the peak of the
emission component.  The FWHM of the H_alpha emission component is 170
km/s.  The TiO absorption bands of the M giant visible in the red part of
the spectrum appear significantly weaker than in quiescence due to the
veiling effect of the bright blue continuum originating from the
outbursting white dwarf companion.  Overall, the spectroscopic behavior is
reminiscent of the one displayed by V919 Sgr in 1991, at the time its
outburst then (cf. IAUC 5317; Ivison et al. 1993, A.Ap. 277, 510), when it
attained a similar peak brightness and colors.  The mean magnitudes and
colors for quiescence are averaged from various sources, all of them
strictly agreeing (see Munari and Jurdana-Sepic 2001, A.Ap. 370, 503), and
Munari et al. have continued monitoring the object over the last couple of
years.  In 2006, V919 Sgr was still in quiescence; when monitoring was
resumed in May 2007, the variable was already rising in brightness; on May
19, it was at B = 13.40 (thus already 0.75 mag brighter than typical
quiescence).  Since then, it has been increasing linearly to its current
brightness.
     E. O. Waagen, American Association of Variable Star Observers (AAVSO),
reports that M. Templeton, AAVSO, has investigated the ASAS-3 V-band data
available for V919 Sgr, finding that between 2001 April and 2004 October 7,
the star fluctuated between V about 13.1 and 12.4, gradually brightening,
and was at V = 12.74 +/- 0.03 on 2004 Oct. 7.021 UT.  No further ASAS-3
observations exist until 2006 Feb. 28.401, when the star was brighter at V
= 12.00 +/- 0.03.  ASAS-3 observations continued until 2006 June 8.229,
when V919 Sgr was at V = 11.86 +/- 0.04.  AAVSO visual magnitude estimates
of V919 Sgr:  1991 Aug. 8.6, 11.0 (M. Koshiro, Suwa-shi, Nagano-ken, Japan);
1993 Sept. 11.85, 11.7 (A. Pereira, Linda-a-Velha, Portugal); 1997 Nov.
18.7, 13.2 (L. Monard, Tiegerpoort, South Africa); (Monard); 1998 Apr. 25.1,
13.0: (Monard); May 18.9, 13.3 (Monard); 31.9, 13.4 (Monard); June 19.9,
13.6 (Monard); 27.8, 13.5 (Monard); July 14.8, 13.6 (Monard); 19.8, 13.8
(Monard); 27.8, 13.8 (Monard); Sept. 19.8, 13.7 (Monard); Oct. 18.7, 13.6
(Monard); 1999 Mar. 1.1, 13.5 (Monard); 26.1, 13.4 (Monard); Apr. 13.0, 13.4
(Monard); 24.0, 13.6 (Monard); May 10.0, 13.5 (Monard); June 11.9, 13.4
(Monard); 22.9, 13.3 (Monard); July 3.8, 13.3 (Monard); 12.76, 13.2
(Monard); Aug. 14.7, 13.2 (Monard); 28.73, 13.2 (Monard); Oct. 6.7, 13.2
(Monard); 2000 Mar. 10.1, 12.9 (Monard); 31.1, 13.0 (Monard); Apr. 7.0, 13.0
(Monard); May 6.1, 13.0 (Monard); 25.9, 13.2 (Monard); June 5.98, 13.1
(Monard); July 5.82, 13.1 (Monard); 20.79, 13.2 (Monard); Aug. 25.74, 13.4
(Monard); Sept. 17.73, 13.5 (Monard); 27.72, 13.4 (Monard); Oct. 29.72, 13.6
(Monard); 2001 Mar. 2.08, 13.4 (Monard); Apr. 3.04, 13.2 (Monard); 23.02,
13.2 (Monard); May 18.87, 13.3 (Monard); July 13.82, 13.5 (Monard); 26.74,
13.4 (Monard); Aug. 20.74, 13.5 (Monard); Oct. 7.73, 13.6 (Monard); 2002
June 11.715, [13.0 (A. Jones, Nelson, New Zealand); 2006 July 22.442, 12.1
(Jones).  V919 Sgr was not seen by Monard during 1996 July 10.8-1997 July
6.8, with limiting visual magnitudes then ranging from 12.1 to 12.6.  S.
O'Connor (Sandys/Somerset, Bermuda) reported V = 13.59 using a CCD camera
on 2005 July 4.271.


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                         (C) Copyright 2007 CBAT
2007 July 13                     (CBET 999)               Daniel W. E. Green