HD 45677(= MWC 142 = FS CMa) is a much studied object, both because of its observability from the northern hemisphere and its peculiarities. The CDS bibliography of the star lists 144 papers published between 1949 and 1996. The object was discovered almost one century ago by Fleming (1898), but the first descriptions were made by Merrill (1925, 1928). Subsequently the star was studied by Swings & Struve (1940, 1943) and by Merrill (1952) who provided line identifications and descriptions of the spectrum documenting its variability. We shall not attempt to provide a summary of the whole literature, but we shall try to summarize what seems to us to be the essential observational characteristics of this star.
The star exhibits a circumstellar dust shell, responsible for a strong infrared radiation excess, possibly seen edge-on (Swings & Allen 1971). The star is not associated neither a with visible nebulosity (Swings 1973), nor with molecular clouds (Brown et al. 1995). The dust shell (or torus) apparently is the cause for the erratic photometric variations in visual magnitude and in colors (Halbedel 1989 and 1991; Bergner et al. 1995) which occupy the interval 7.55 < V < 8.58 and 0.0 < B-V < 0.11. Halbedel (1991) suggests that a quasi-period of 297 days exists, besides a general flickering (Perez et al. 1994). From satellite polarimetric observations in the ultraviolet, Schulte-Ladbeck et al. (1992) conclude that a bipolar reflection nebula is present beside the dust shell. A study of the satellite ultraviolet made Brown et al. (1995) concludes that in the circumstellar disk or torus, predominate the micron-size particles, whereas the sub-micron sized ones are depleted by radiation pressure. The accumulation of micron sized grains might lead eventually to the formation of planetesimals. Sitko et al. (1994) conclude from a comparison of data separated by more than a decade that the variations in photometry and in the spectrum are due to changes in the dust obscuration
The IUE spectra have been studied among others by Grady et al. (1993). They conclude from enhanced redward absorption components that the material shows clear indications of accretions onto the star.
As far as the evolutionary status of HD 45677 goes, the views found in the literature diverge widely. Some authors see the object as a post asymptotic giant branch object on its way to become a planetary nebula. Others insist that it is an object in its contraction phase toward the main sequence, calling it a Herbig Be-Ae object. Some authors go even one step further and state that it is an object in a pre-beta Pictoris phase. It is only fair to say that each of these classifications has its difficulties. For a pre-main sequence object it is too far out of the galactic plane (190 pc) and it has no nebulosity associated with it, a fact which is basic to the classification as a Herbig Be-Ae object. For an evolved object one finds no wind, as usual, but instead accretion.
The aim of the present paper, as well of the others of this series, is to provide an identification list over an extended wavelength interval, together with a list of equivalent widths of the emission lines. This should lead to an improved understanding of B[e] stars and their shells.