3 Spectral classification

The spectral types of the numerous OB stars present in both LH 104 and LH 101 were determined comparing our data with Walborn $\&$ Fitzpatrick's (1990) atlas of digital spectra. Further details of the spectral classification are described in Paper I. The galactic stars were discriminated by their approximate heliocentric near zero radial velocity. In Fig. 4 the spectra of a few evolved and unevolved OB stars are plotted in the range of $\lambda\lambda$4000 to 4800 Å.

  

Figure 4: Selected rectified spectra of evolved and unevolved stars in LH 101

3.1 Individual interesting stars

3.1.1 The O3If star 5-31(=Westerlund 19)

The star 5-31 (W19) coincides with the location of the NIR 1 source (Jones et al. 1986). Its optical spectrum shows a narrow NIV $\lambda$4058 Å emission feature and NV $\lambda$$\lambda$4604,4620 Å absorption lines (Fig. 4). The NIV $\lambda$4058 emission line is slightly stronger than NIII $\lambda$4640 emission, and with the HeII $\lambda$4686 Å line also in emission this star presents the characteristics of an O3 supergiant which we classify O3If^*. It is also interesting to note the presence of CIII-IV $\lambda$4652 emission lines similar to NIII $\lambda$4634-41.

  

Figure 5a: Selected rectified spectra of the components a) and b) of the complex star Sk -69 249. b) and the WR Brey 91

 

Figure 5b: Rectified spectrum of Sk -69 247

 

Figure 5c: Rectified spectrum of the [Be] star Sk -69 259 showing sharp emission lines. Note also the broader He II $\lambda$ 4686 emission. A few emission lines of FeII and [FeII] are identified

 

Figure 5d: Spectrograms of the three WR star systems in LH104

3.1.2 Stars 5-65 and 5-66 = Sk -69 249

This star, located 3$^{\prime\prime}$ east of the Wolf-Rayet star Brey 91 of type WN9 (Breysacher 1981), appears to consist of two components (a) and (b) of similar magnitude separated by only 1.6$^{\prime\prime}$ (Fig. 3). The spectrum of the northern component (a) = 5-65 shows HeII $\lambda$4686 and NIII $\lambda$4640 in emission (Fig. 5a). The HeI $\lambda$4471 appears similar to HeII $\lambda$4541, thus we classify this star as O7If. From several spectra obtained during consecutive nights, the emission lines of NIII and HeII show large amplitude radial velocity variations. This star probably is a spectroscopic binary. The spectrum of the southern component (b) = 5-66 shows rather strong absorptions of SiIV $\lambda$$\lambda$4089, 4116, SiIII $\lambda$$\lambda$4552, 68, 75 and the blend OII and CIII $\lambda$4650, thus we classify it as a supergiant B0I. Without sufficient spatial resolution, this star contaminates the northern component.

3.1.3 Star 5-76 = Sk -69 247 = HD 269923

The visually brightest star in LH 101, HD 269923 has been classified by Fitzpatrick (1991) as A0Ia⁺. In our spectra, P Cygni profiles are well seen in H$\beta$ and H$\gamma$. Particularly prominent is the P Cyg profile in H$\beta$, with extended emission wings (Fig. 5b). This kind of profiles are often observed in Luminous Blue Variable (LBV) type stars (e.g. Walborn 1997). The spectrum of HD 269923 also presents many strong photospheric absorption lines of Fe II.

3.1.4 Star 4-73 = Sk -69 259 = HD 38489 = S 134

This luminous star located at the northern edge of the association LH 104, was studied by Shore $\&$ Sanduleak (1983). Our spectrum of $\delta$$\lambda$ $\sim$ 1Å (Fig. 5c) shows very narrow emissions of low-excitation metals, and strong nebular and Balmer emission lines. As the variations of these strong lines affect the photometry the Vand B-V magnitudes have to be corrected by $0\hbox{$.\!\!^{\rm m}$}24$ and $0\hbox{$.\!\!^{\rm m}$}20$,respectively (Zickgraf et al. 1986). The widths of a few lines are listed in Table 3. In order to have a good accuracy on sharp lines the third column indicates FWHM values obtained after deconvolution by a gaussian of FWHM = 1 Å. These characteristics with an H$\beta$ equivalent width of $\sim$ 200 Å confirm the B[e] supergiant type of this star described by Zickgraf (1990). Our spectrum has rather better signal/noise ratio than those published previously, and allows to point out very well the presence of a relatively weak and broad HeII $\lambda$4686 emission line of FWHM = 15.2 Å, an indication for a hot, high velocity stellar wind (Zickgraf et al. 1986).

 

Table 3: Emission line widths in the spectrum of HD 38489