Galactic cluster dwarfs

This work describes the results of studies into galactic cluster brown and white dwarfs. Galactic cluster dwarfs have a known age increasing their use to the observer and allowing meaningful comparisons to models to be made. For brown dwarfs this is to increase knowledge of the initial mass function and star formation. For white dwarfs it is to increase understanding of the relationship between the progenitor star and its resultant white dwarf.;Chapter 4 describes a deep, large area (2.5 square degrees) survey of the Pleiades using optical (I and Z) and infrared (J) data. Three possible L dwarfs and six possible T dwarf new members of the cluster remain after proper motion measurements and follow up infrared photometry.;Chapter 5 presents results of a catalogue survey of Melotte 111 which more than doubled the number of stellar members of the cluster. Also described is a deep survey of the cluster centre, with follow up photometry, proper motions and spectra. Thirteen brown dwarf candidates are discovered.;Chapter 6 describes work which measured proper motions of 143 known brown dwarfs using WFCAM and 2MASS. Five candidate wide binaries are discovered, as well as 8 fast moving L dwarfs that may belong to the thick disc. The moving group method was used to identify 25 dwarfs as possible members of the Hyades, Ursa Major and Pleiades moving groups.;Chapter 7 presents the results of a spectroscopic study of 9 Praesepe white dwarfs. One is shown to be a non member of the cluster and another a possible double degenerate. A more precise initial-final mass relation is calculated.