We present a study of the structure and dynamics of the Corona Borealis Supercluster ( z \approx 0.07 ) based on the redshifts of 528 galaxies in the supercluster .
The galaxy distribution within Corona Borealis is clumpy and appears overall to be far from relaxed .
Approximately one-third of the supercluster galaxies lie outside of the Abell clusters in the supercluster .
A background supercluster at z \approx 0.11 makes a substantial contribution to the projected surface density of galaxies in the Corona Borealis field .
In order to estimate the mass of the supercluster , we have assumed that the mass of the supercluster is proportional to v ^ { 2 } r , where v and r are suitable scale velocity and radius , respectively , and we have used N -body simulations of both critical- and low-density universes to determine the applicability of standard mass estimators based on this assumption .
Although superclusters are obviously not in equilibrium , our simulations demonstrate that the virial mass estimator yields mass estimates with an insignificant bias and a dispersion of only \sim 25 % for objects with overdensities \gtrsim 5 .
Non-uniform spatial sampling can , however , cause systematic underestimates of as much as 30 % .
The projected mass estimator ( Bahcall & Tremaine 1981 ) is less accurate but still provides useful estimates in most cases .
All of our simulated superclusters turn out to be bound , and based on the overdensity of the Corona Borealis supercluster , we believe it is also very likely to be bound and may well have started to collapse .
The mass of Corona Borealis is at least 3 \times 10 ^ { 16 } h ^ { -1 } M _ { \sun } ( h is the Hubble constant in units of 100 km s ^ { -1 } Mpc ^ { -1 } ) , which yields a B _ { AB } -band mass-to-light ratio of 564 h { M \overwithdelims ( ) L } _ { \sun } on scales of \sim 20 h ^ { -1 } Mpc .
The background supercluster has a similar mass-to-light ratio of 726 h { M \overwithdelims ( ) L } _ { \odot } .
By comparing the supercluster mass-to-light ratios with the critical mass-to-light ratio required to close the universe , we determine that \Omega _ { 0 } \gtrsim 0.4 on supercluster scales .