The Curious Case of ASAS J174600-2321.3: an Eclipsing Symbiotic Nova in Outburst?

Volume 43 number 1 (2015)

Stefan Hümmerich: Stiftstr. 4, Braubach, D-56338, Germany; American Association of Variable Star Observers (AAVSO), Cambridge, MA; Bundesdeutsche Arbeitsgemeinschaft für Veränderliche Sterne e.V. (BAV), Berlin, Germany; stefan.huemmerich@gmail.com
Sebastián Otero: Olazabal 3650-8 C, Buenos Aires, 1430, Argentina; American Association of Variable Star Observers (AAVSO), Cambridge, MA
Patrick Tisserand: Sorbonne Universités, UPMC Univ Paris 06, UMR 7095, Institut d’Astrophysique de Paris, F-75005 Paris, France; CNRS, UMR 7095, Institut d’Astrophysique de Paris, 98 bis Boulevard Arago, F-75014 Paris, France
Klaus Bernhard: Kafkaweg 5, Linz, 4030, Austria; American Association of Variable Star Observers (AAVSO), Cambridge, MA; Bundesdeutsche Arbeitsgemeinschaft für Veränderliche Sterne e.V. (BAV), Berlin, Germany

Abstract

The star ASAS J174600-2321.3 was found to exhibit peculiar photometric variability (conspicuous brightening of ~4 magnitudes (V), fast luminosity declines, intrinsic pulsations). It was rejected as an RCB candidate in recent investigations on spectroscopic grounds. We have collected and present all available data from public sky surveys, photometric catalogues, and the literature. From an analysis of these data, we have identified ASAS J174600-2321.3 as a long-period eclipsing binary (Porb = 1,011.5 days). The primary star, which is probably a white dwarf, is currently in outburst and exhibits the spectral characteristics of a reddened, early F-type supergiant; the secondary star is a giant of spectral type late M. We discuss the possible origin of the observed brightening, which is related to the primary component. ASAS J174600-2321.3 is most certainly an eclipsing symbiotic binary - probably a symbiotic nova of GCVS type NC - that is currently in outburst. However, further photometric and spectroscopic data are needed to confirm this.