We predict the survival time of initially bound star clusters in the solar neighbourhood taking into account : ( 1 ) stellar evolution , ( 2 ) tidal stripping , ( 3 ) shocking by spiral arms and ( 4 ) encounters with giant molecular clouds .
We find that the predicted dissolution time is \mbox { $t _ { dis } $ } = 1.7 ( \mbox { $M _ { i } $ } / 10 ^ { 4 } \mbox { $M _ { \odot } $ } ) ^ { 0.67 } Gyr for clusters in the mass range of 10 ^ { 2 } < \mbox { $M _ { i } $ } < 10 ^ { 5 } \mbox { $M _ { \odot } $ } .
The resulting predicted shape of the logarithmic age distribution agrees very well with the empirical one , derived from a complete sample of clusters in the solar neighbourhood within 600 pc .
The required scaling factor implies a star formation rate of 4 ~ { } 10 ^ { 2 } M _ { \odot } Myr ^ { -1 } within 600 pc from the Sun or a surface formation rate of 3.5 ~ { } 10 ^ { -10 } M _ { \odot } yr ^ { -1 } pc ^ { -2 } for stars in bound clusters with an initial mass in the range of 10 ^ { 2 } to 3 ~ { } 10 ^ { 4 } M _ { \odot } .