We report new results in our continuing study of the unique compact ( 1 pc extent ) , nearby ( d = 97 pc ) , young ( t = 9 Myr ) stellar cluster dominated by the B9 star \eta Chamaeleontis .
An optical photometric survey spanning 1.3 \times 1.3 pc adds two M5 – M5.5 weak-lined T Tauri ( WTT ) stars to the cluster inventory which is likely to be significantly complete for primaries with masses M > 0.15 M _ { \odot } .
The cluster now consists of 17 primaries and \simeq 9 secondaries lying within 100 AU of their primaries .
The apparent distribution of 9:7:1 single : binary : triple systems shows 2 - 4 \times higher multiplicity than in the field main sequence stars , and is comparable to that seen in other pre-main sequence ( PMS ) populations .
The initial mass function ( IMF ) is consistent with that of rich young clusters and field stars .
By extending the cluster IMF to lower masses , we predict 10 - 14 
additional low mass stars with 0.08 < M < 0.15 M _ { \odot } and 10 - 15 brown dwarfs with 0.025 < M < 0.08 M _ { \odot } remain to be discovered .
The \eta Cha cluster extends the established stellar density and richness relationship for young open clusters .
The radial distribution of stars is consistent with an isothermal sphere , but mass segregation is present with > 50 percent of the stellar mass residing in the inner 6 arcmin ( 0.17 pc ) .
Considering that the \eta Cha cluster is sparse , diffuse and young , the cluster may be an ideal laboratory for distinguishing between mass segregation that is primordial in nature , or arising from dynamical interaction processes .