1997A&AS..123..455W

The OB association LH47 inside the superbubble N44 in the Large Magellanic Cloud (LMC) is analyzed with CCD photometry. For the bright blue stars spectra in the optical and UV have been taken. The observed U, B, and V magnitudes and colours are converted to T_eff and L. From isochrone fits to the colour magnitude diagram (CMD), we find an age of the association of about 5 to 6-Myr. The stellar population outside the shell is of similar age, so there is no direct evidence for sequential star formation. The slope of the luminosity function (γ=0.24) agrees with what has been found for other young associations. We compare two methods to derive the slope of the initial mass function (IMF). First we count all stars along the main sequence in the BV CMD. Second we count the stars between stellar evolutionary tracks in the Hertzsprung-Russell diagram (HRD). Both methods give mainly the same result, i.e. x=1.37 and x=1.22, respectively. The IMF of the stars outside the shell shows a slightly steeper slope than inside the shell. The slope of the IMF is very similar to values found for other associations and open clusters as well as in the solar neighborhood, thus supporting the idea of an universal shape of the IMF. LH47 turns out to be a well behaved young association embedded in a molecular cloud.