  We report the results of CCD V and R photometry of the RR Lyrae stars in M2.
The periodicities of most variables are revised and new ephemerides are
calculated. Light curve decomposition of the RR Lyrae stars was carried out and
the corresponding mean physical parameters [Fe/H] = -1.47, Teff = 6276 K, log L
= 1.63 Lsun and Mv = 0.71 from nine RRab and [Fe/H] = -1.61, M = 0.54 Msun,
Teff = 7215 K, log L = 1.74 Lsun and Mv = 0.71 from two RRc stars were
calculated. A comparison of the radii obtained from the above luminosity and
temperature with predicted radii from nonlinear convective models is discussed.
The estimated mean distance to the cluster is 10.49 +- 0.15 kpc. These results
place M2 correctly in the general globular cluster sequences Oosterhoff type,
mass, luminosity and temperature, all as a function of the metallicity. Mean
relationships for M, log L/Lsun, Teff and Mv as a function of [Fe/H] for a
family of globular clusters are offered. These trends are consistent with
evolutionary and structural notions on the horizontal branch. Eight new
variables are reported.
