1 Introduction

Symbiotic stars are interacting binaries, in which an evolved giant transfers material to much hotter, compact companion. In a typical configuration, a symbiotic binary comprises a red giant transferring material to a white dwarf via a stellar wind. Amongst the evidence for this predominant mass-transfer mechanism is the fact that ellipsoidal light variations, characteristic of tidally distorted stars, are rarely observed for symbiotic stars. Thus far, only four systems, T CrB (Belczynski et al. 1998), CI Cyg (Mikoajewska & Belczynski 2000), EG And (Wilson & Vaccaro 1997) and BD-21 3873 (Smith et al. 1997), are known to have the ellipsoidal light variations of a distorted giant. In some symbiotic systems, the red giant is replaced by a yellow giant, and the white dwarf by a main-sequence or neutron star.

Most symbiotic stars ($\sim 80\%$) contain a normal giant star and these, based on their near-IR colours (showing the presence of stellar photospheres, $T_{\rm eff} \sim$ 3000 - 4000 K), are classified as S-type systems (stellar). The remainder contain Mira variables and their near-IR colours indicate the combination of a reddened Mira and dust with temperature of $\sim 1000$ K, giving away the presence of warm dust shells; these are classified as D-type systems (dusty). The distinction between S and D types seems to be one of orbital separation: the binary must have enough room for the red giant/Mira variable, and yet allow it to transfer sufficient mass to its companion. In fact, all symbiotic systems with known orbital periods (of the order of a few years) belong to the S-type, while the orbital periods for D-type systems are generally unknown presumably longer than periods covered by existing observations. Although there may well be binaries consisting of normal giants and white dwarfs with very large orbital separations, however they will be never recognized as symbiotic systems because there would be no interaction giving rise to a symbiotic appearance (see next section). For a detailed review of symbiotic stars, we refer the reader to Mikoajewska 1997.

Two catalogues of symbiotic stars have been published. The first was by David Allen in 1984 (Allen 1984); it included 129 symbiotic stars and 15 possible symbiotic objects with a concise summary of available observational data, finding charts and optical spectra for most of listed objects. The second catalogue was by Scott Kenyon in 1986 Kenyon 1986; it included 133 symbiotic stars and 20 possible symbiotic objects, as well as tables describing selected observational properties of all the objects and a spectroscopic summary of a selected sample. Kenyon's work also provides the reader with an excellent overview and bibliography of selected symbiotic stars.

Since 1986, a number of papers have presented surveys of large samples of symbiotic stars, e.g. Mikoajewska et al. 1997,Mürset & Schmid 1999 (optical spectra), van Winckel et al. 1993,Ivison et al. 1994 (emission line profiles and radial velocity measurements) Munari et al. 1992 (optical and IR photometry), Kenyon et al. 1988,Whitelock & Munari 1992 (IRAS observations), Seaquist & Taylor 1990,Seaquist et al. 1993,Seaquist et al. 1995,Ivison et al. 1991,Ivison et al. 1995 (radio emission), Ivison et al. 1994,Schwarz et al. 1995 (searches for maser emission), Meier et al. 1994 (IUE observations), Bickert et al. 1997,Mürset et al. 1997 (X-ray emission), Whitelock 1987 (symbiotic miras), Mürset & Nussbaumer 1994 (symbiotic novae), Mürset et al. 1996,Morgan 1992 (extragalactic symbiotics) and in-depth investigations, e.g. Iijima 1988,Mikoajewska & Kenyon 1992,Ivison et al. 1993,Skopal1994,Godon 1996 for AX Per alone. New stars have been included in the family of symbiotic stars each year and, at the same time, better data have been collected and better data analysis has been performed for a number of well-known symbiotic stars. The aim of this work is to present the symbiotic star research community with a comprehensive compilation of existing data collected from a number of astronomical journals, electronic databases and unpublished data resources. For many objects a new classification has been necessary: some have been confirmed as symbiotic stars; some have been rejected; some new objects have been added. Our catalogue lists 188 symbiotic stars and 30 objects suspected of being symbiotic stars.