We present high-resolution HST imaging in the optical ( WFPC2 ) and near-infrared ( NICMOS ) of a disk region 1 kpc NE of the starburst core in the nearby galaxy M82 .
This region , M82 “ B , ” has been suspected to be a fossil starburst site in which an intense episode of star formation occurred over 100 Myr ago , and our new observations confirm this intepretation .
M82 thus presents us with the opportunity to observe both active and evolved starburst environments at close range .

The surface brightness of M82 B is well above normal for galactic disks and comparable to the core surface brightnesses in spiral galaxies .
Its intrinsic surface brightness at an age of 10 Myr was comparable to that found in the present-day nuclear starburst , indicating an event of comparable amplitude .

We find a large , evolved system of super star clusters in M82 B .
Using size as a criterion to distinguish cluster candidates from point sources , we identify a total of 113 super star cluster candidates .
We use a two-color BVI diagram and evolutionary spectral synthesis models to separately estimate the extinction and age of each cluster .
The clusters range in absolute magnitude from M _ { V } ^ { 0 } = -6 to –10 , with a peak at –7.5 .
The derived age distribution suggests steady , continuing cluster formation at a modest rate at early times ( > 2 Gyr ago ) , followed by a concentrated formation episode \sim 600 Myr ago and more recent suppression of cluster formation .
The peak episode coincides with independent dynamical estimates for the last tidal encounter with M81 , which presumably induced the starburst .

Our J and H band observations resolve the bright giant population in M82 ’ s disk for the first time .
Star formation evidently continued in M82 B until about 20 – 30 Myr ago , but none is found associated with the youngest generations in the nuclear starburst ( age \lesssim 15 Myr ) .

After correcting the cluster luminosity function to a fiducial age of 50 Myr , we find that the bright end is characterized by a power-law slope with \alpha = -1.2 \pm 0.3 , similar to that of other young cluster systems in interacting galaxies .
There is tentative evidence for broadening of the luminosity function due to dynamical destruction of lower mass clusters .
Cluster sizes ( 2.34 \leq R _ { eff } \lesssim 10 pc , or 2.4 \lesssim R _ { core } \lesssim 7.9 pc ) and estimated masses ( a median of 10 ^ { 5 } M _ { \odot } ) are consistent with values found for young super star cluster populations in M82 ’ s core and other galaxies and with the progenitors of globular clusters .