X-ray emission from brown dwarfs: A sequence of temperatures and ages

We propose to observe several brown dwarfs. Two such substellar objects weredetected as Xray sources for the first time recently with ROSAT. It is notknown, how brown dwarfs emit Xrays, possibly as coronal emission like verylatetype stars. In that case, we should expect a correlation of brown dwarfXray emission with spectral type, ie. temperature, and also with age, ie.bolometric luminosity. After the deuterium burning phase, central temperatureand, hence, temperature gradient will decrease. Hence, convection and Xrayemission may cease. Our targets, 2 fields with one brown dwarf each and onefield with several substellar objects, are selected to probe a range in age andtemperature, to study cooling timescale and internal structure of brown dwarfs. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]