Reappearance of 22 GHz water maser in proto-planetary nebula OH17.7-2.0.
ATel #5211; P. Wolak, M. Szymczak, A. Bartkiewicz, E. Pazderski, A. J. Kus, A. Kepa, K. Katarzynski, K. M. Borkowski, R. Feiler, J. Mazurek, W. Szymanski, J. Filarecki, J. Krol (Torun Centre for Astronomy, Nicolaus Copernicus University)
on 17 Jul 2013; 13:21 UT
Credential Certification: Pawel Wolak (wolak@astro.uni.torun.pl)
Subjects: Radio, Star, Variables
We observed OH17.7-2.0 (also known as: IRAS18276-1431, V445 Sct), a young proto-planetary nebula
(Sanchez Contreras et al., 2007, ApJ, 656, 1150; Bains et al., 2003, MNRAS, 338, 287), in the 22 GHz water maser line using a new K-band receiver at the Torun 32m radio telescope. The system equivalent flux density was about 480 Jy and spectral resolution was 0.03 km/s.
A maser
feature
of about 25 Jy at +56.4 km/s was detected, in the velocity range of -20 to 160 km/s searched,during the receiver commissioning on 2013 Feb 11.
Subsequent monitoring of the complex non-Gaussian profile revealed systematic
changes of velocity
(0.09 km/s over the period of 140 days) and of
line-width (0.60 - 0.70 km/s).
The water maser of OH17.7-2.0 was first detected in 1983 (Nyman et al., 1986, AA, 160, 352) and following dramatic decrease of its intensity disappeared completely after 1990 (Engels, 2002, AA, 388, 252). The present observations imply that the
emission reappeared
sometime between 2010 and 2013,
i.e. after more than 20 years of no detection.
