ATEL #3946                                                           ATEL #3946

Title:  Discovery of a new outburst of the bipolar jet-emitter, stable
               H-burning WD in the symbiotic binary Hen 3-1341
Author: U. Munari, A. Milani, A. Siviero, S. Dallaporta, G. L. Righetti,
               P. Valisa, A. Frigo, E.  Tamajo, P.  Ochner (INAF Padova Astronomical
               Observatory; ANS Collaboration; Dept.  of Physics and Astronomy of
               the University of Padova; Dept.  of Physics of the University of Zagreb)

Queries:        ulisse.munari@oapd.inaf.it
Posted: 1 Mar 2012; 11:36 UT
Subjects:Optical, Ultra-Violet, X-ray, Cataclysmic Variable, Nova,
               Variables

When a week ago we resumed the optical monitoring following its emergence 
from the conjunction with the Sun, we found that the symbiotic star Hen 
3-1341 (V2523 Oph) is undergoing a bright outburst, the first one occurring 
since the last outburst that peaked in brightness in mid 1999.  During
the preceding quiescence, the object went down to B=14.179, V=13.353,
Rc=12.053, Ic=10.861 on 2009 Sept 11.798 UT, and our last measurement before
the current outburst reported it at B=13.948, V=13.231, Rc=11.798 and
Ic=10.659 on 2011 July 3.909 UT.  The object is still on the rise and has
not yet reached maximum brightness as suggested by our latest measurements,
giving respectively for Feb 23.194, Feb 27.190 and March 1.168 UT the
following values: B=12.248, 12.222, 12.199; V=11.640, 11.609, 11.583;
Rc=10.942, 10.900, 10.880; and Ic=10.170, 10.147, 10.128. They correspond
to a brightening of 2 magnitudes in B band so far.
Hen 3-1341 is a noteworthy object because during its last outburst in 1999
we discovered bipolar jets emanating form it (Tomov, Munari, Marrese A&A
354, L25; Munari et al.  2005, MNRAS 360, 1257), one of the few symbiotic
stars known to show them.  In 1999 we found that the bipolar jets appeared
at outburst maximum and declined in intensity with outburst decline.  The
strength of the bipolar jets paralleled the intensity of the wind blowing
from the outbursting WD. The temperature and luminosity of the WD, as
derived from photoionization analysis, strongly suggested that it was in
stable H-burning conditions during quiescence. Thus, the optical "outbursts"
could be caused by the burning envelope of the WD to react by expanding
to an increase in the mass transfer from the M giant companion, with the
temperature of the corresponding black-body cooling from 10(5) to 10(4)
K.
The rising, current brightness of Hen 3-1341 is still about 1 mag fainter
that the peak brightness it reached during the 1999 outburst.  The 2012
seasonal visibility has just begun, and this offers the possibility to
monitor Hen 3-1341 to study the onset and evolution of the bipolar jets,
this time being better prepared about what to look.
We secured on Feb 27 a 4000-8600 Ang high resolution Echelle spectrum of
Hen 3-1341 with the multi-mode spectrograph attached to the 0.6m telescope
at Varese Observatory, and on March 1 a low resolution, absolutely fluxed
3300-7700 Ang spectrum with the 1.22m Asiago telescope of the University
of Padova, Dept.  of Physics and Astronomy.  The outburst spectrum has largely
changed in comparison with that in quiescence.  All high ionization emission
lines (HeII, [NeV], [FeVII], Raman scattering of OVI< etc.) have gone,
and a strong blue continuum has completely overwhelmed the TiO absorption bands
of the M4 giant companion to the outbursting WD.  The only significant emission
lines that remain visible are the Balmer lines, neutral helium and weak
[OIII].  The Balmer continuum remains in strong emission (responsible for
largely negative value of the U-B photometric index).  Noteworthy, the
strong P-Cyg absorption components visible at maximum brightness during
the 1999 outburst have not yet developed, neither have the bipolar jets that
were observed on Balmer lines at projected radial velocities of +820 and
-820 km/sec.  We could expect them to emerge soon, as the star will be
approaching maximum brightness during the current outburst.