We present a detailed study of two luminous super star clusters in the starburst galaxy M82 .
Spectra , covering 3250–8790 Å at a resolution of 1.6 Å , were obtained at the 4.2 m William Herschel Telescope ( WHT ) for cluster F and the highly reddened cluster L. We compare the strengths of the observed Balmer absorption lines and the Balmer jump in the blue spectrum of F with theoretical model cluster spectra using the PEGASE spectral synthesis code to derive an age of 60 \pm 20 Myr .
For cluster L , we find that the similarities in the strength of the Ca II triplet and overall spectral appearance with cluster F suggest a similar age .
The brightness and compactness of cluster F make it an ideal candidate for determining its dynamical mass by measuring the velocity dispersion .
We present the results of such an investigation based on echelle spectra at a resolution of 8 km s ^ { -1 } obtained at the WHT from 5760–9140 Å .
By cross-correlating various wavelength regions in the spectrum of cluster F with cool giant and supergiant template stars , we derive a velocity dispersion and , by application of the virial theorem , determine a dynamical mass of 2 \times 10 ^ { 6 } M _ { \odot } .
We compare our derived mass with those determined for other young super star clusters and discuss whether our derived parameters are consistent with cluster F being able to survive to become a globular cluster .