The main problem in using the inverse Abel transform of an experimentally observed function is that it involves numerical differentiation, which amplifies the errors affecting the measurements. This difficulty can be overcome by using spectral expansion methods, with coefficients obtainable through a numerical integration. The inaccuracy of the

The amount of data produced by large observational facilities and space missions has led to the archiving and on-line accessibility of much of these data, available to the entire astronomical community, and allowing a much wider multi-frequency approach of astronomical research than previously possible. Here I intend to draw attention to these

Not Available

Not Available

Not Available

We describe a spectroscopic test capable of providing direct confirmation of the substellar nature of brown dwarf candidates. While the conditions for substantial lithium burning are reached even in very low-mass stars, in substellar objects with less than 0.06 solar mass such conditions are never attained and Li is expected to be preserved