Stars and brown dwarfs, spatial distribution, multiplicity, X-rays, discs, and the complete mass function of the σ Orionis cluster

The young sigma Orionis cluster in the Orion Bell is an incomparable site for studying the formation and evolution of high-mass, solar-like, and low-mass stars, brown dwarfs, and substellar objects below the deuterium burning mass limit. The first version oft he Mayrit catalogue was a thorough data compilation of cluster members and candidates, which is regularly used by many authors of different disciplines. I show two new applications of the catalogue and advance preliminar results in very wide binarity and the initial mass function from IFS to 0.035 M., in sigma Orionis. The making-up of a new version of the Mayrit catalogue with additional useful data is in progress.