As part of the Araucaria Project , we present the first spectral catalog of supergiant stars in the Local Group dwarf irregular galaxy WLM .
In assigning a spectral classification to these stars we accounted for the low metal content of WLM relative to the galactic standards used in the MK process , by using classification criteria developed for B and A supergiants contained in the Small Magellanic Cloud .
Our spectral catalog shows that our higher S/N spectroscopic sample of 19 objects contains at least 6 early-B ( B0-B5 ) supergiants and 6 late-B and early-A ( B8-A2 ) stars of luminosity class between Ia and II , as well as an O7 V star and an O9.7 Ia star .
The spectra of several of these stars is of sufficiently high quality for a determination of the stellar parameters and abundances .
We have acquired also a second set of lower S/N spectra for mostly BA stars , however their quality does not allow a further analysis .
We have carried out a quantitative analysis for three early-B supergiants .
The mean oxygen abundance we derive is 12 + log ( O/H ) = 7.83 \pm 0.12 .
This value agrees very well with the measurement that is obtained from H ii regions .
We therefore find no additional evidence for the discrepancy between stellar and nebular oxygen abundances measured for a single A-type supergiant by Venn et al .
The analysis of B- and A-type supergiants yields compatible results for nitrogen , silicon and magnesium .
We show that the photometric variability of the blue supergiants included in our spectroscopic sample is negligible for the use of these stars as distance indicators .