Identification of new Galactic symbiotic stars with SALT. I. Initial discoveries and other emission line objects

Abstract

We introduce the first results from an ongoing, systematic survey for new symbiotic stars selected from the AAO/UKST SuperCOSMOS H$\alpha$ Survey (SHS). The survey aims to identify and characterise the fainter population of symbiotic stars underrepresented in extant catalogues. The accreting white dwarfs (WDs) in symbiotic stars, fuelled by their red giant donors with high mass loss rate winds, make them promising candidates for type Ia supernovae. Several candidates were observed spectroscopically with the Southern African Large Telescope (SALT). A total of 12 bona-fide and 3 possible symbiotic stars were identified. The most remarkable example is a rare carbon-rich symbiotic star that displays coronal [Fe X] $\lambda$6375 emission, suggesting it may be a supersoft X-ray source with a massive WD. Several other emission line objects with near-infrared colours similar to symbiotic stars are listed in an appendix, including 6 B[e] stars, 4 planetary nebulae (PNe), 2 possible Be stars, one [WC9] Wolf-Rayet (WR) central star of a PN and one WC9 WR star. These initial discoveries will help shape and refine the candidate selection criteria that we expect will uncover several more symbiotic stars as the survey progresses.

Accepted for publication in MNRAS. 17 pages, 12 figures and 3 tables

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