High quality spectra of 90 blue supergiant stars in the Large Magellanic Cloud are analyzed with respect to effective temperature , gravity , metallicity , reddening , extinction and extinction law .
An average metallicity , based on Fe and Mg abundances , relative to the Sun of [ Z ] = -0.35 \pm 0.09 dex is obtained .
The reddening distribution peaks at E ( B-V ) = 0.08 mag , but significantly larger values are also encountered .
A wide distribution of the ratio of extinction to reddening is found ranging from R _ { \mbox { \scriptsize \sc v } } = 2 to 6 .
The results are used to investigate the blue supergiant relationship between flux-weighted gravity , g _ { \mbox { \scriptsize \sc f } } \equiv g/ T _ { \mbox { \scriptsize \em eff } } ^ { 4 } , and absolute bolometric magnitude M _ { bol } .
The existence of a tight relationship , the FGLR , is confirmed .
However , in contrast to previous work the observations reveal that the FGLR is divided into two parts with a different slope .
For flux-weighted gravities larger than 1.30 dex the slope is similar as found in previous work , but the relationship becomes significantly steeper for smaller values of the flux-weighted gravity .
A new calibration of the FGLR for extragalactic distance determinations is provided .