1 Introduction

This is the second paper in a series of three, presenting the enigmatic variability of the Wolf-Rayet (WR) object WR46 (HD104994). In Veen et al. (2002a, hereafter Paper I) photometric monitoring of the object is presented and investigated. A double-wave character is revealed, although it is not very significant. Another remarkable conclusion reached in Paper I is that the period changed from $P_{\rm dw}^{89}=0.2825$ d in 1989 to $P_{\rm dw}^{91}=0.2727$ d in early 1991, while the object brightened gradually in the meantime by 0 $.\!\!^{\rm m}$12. Such a period-change is rather unsettling to the interpretation as a binary. Alternatively, the system could be a multi-mode pulsator showing different modes in different epochs. Also the occurence of a photometric second frequency $f_{\rm x}$ (Paper I) can be explained in a natural way by such a model. Yet, the large radial-velocity amplitude and its typical time scale on the order of the photometric double-wave is, in turn, problematic for this interpretation. Full consideration of both models is deferred to Veen et al. (2002b; hereafter Paper III).

Figure 1: Three nights of observing the He II 4686 emission line at low resolution (28 Feb., 1, 2 Mar. 1990) illustrate the variability from night-to-night.

Figure 2: Simultaneous behaviour of (from left to right) the O VI 3811/34, N V 4604/20 and He II 5411 emission lines during the night of 16-17 February 1991.

In the present paper we investigate the spectroscopic variability of WR46 and show it to be consistent with a true Population I WR nature. The following section presents the data of five years of spectroscopic monitoring in the last decade, obtained simultaneously with our photometry (Paper I). Section 3 presents the line flux and radial-velocity measurements. In Sect. 4 we present the temporal behaviour of the spectral data, i.e., folded radial-velocity and EW curves, time-delays, two (possibly) non-periodic phenomena, and the long-term behaviour. Section 5 discusses the WR nature of the object. Section 6 summarizes all available spectroscopic observations and their inferences. For the observational history of the object we refer to Paper I, and for the issue of how the variability of WR46 relates to that of other WR stars we refer to Paper III. Our interpretation of the observed spectroscopic and photometric variability is presented in Paper III.