We report the discovery of two L dwarfs (the new spectral class defined for dwarfs cooler than the M type) in a two-epoch CCD proper motion survey of 413 square degrees, complemented by infrared photometry from DENIS. One of them has a strong lithium line, which for very cool dwarfs is a proof of brown dwarf status. The other is a common proper

The neutrino production rate strongly depends on the temperature, and a small variation of chemical composition in the central regions can imply a large variation of neutrino flux. For some values of their frequencies and wavenumbers, the internal waves e xcited at the bottom of the solar convective zone are able to propagate until the central

A possible discrepancy found between the determination of mass of the intracluster medium (ICM) from gravitational lensing data and that from X-ray observations has been much discussed in recent years. For instance, Miralda-Escudé & Babul found that the mass estimate derived from gravitational lensing can be as much as a factor of 2-2.5 larger than

This article presents a theoretical framework for the evolution of the light-element nuclides in the Galactic disk. By understanding this evolution correctly, we can reliably obtain the primordial abundances of the nuclides D, 4He, and 7Li. We use two key assumptions, those of (1) infall of metal-poor gas to the disk at an increasing rate and (2)

This paper presents the first results obtained with the Jodrell Bank-IAC two-element 33-GHz interferometer. The instrument was designed to measure the level of the cosmic microwave background (CMB) fluctuations at angular scales of 1 deg-2 deg. The observations analysed here were taken in a strip of the sky at Dec.=+41 deg with an element

CCD observations of the gravitational lens system Q0957+561A, B in the BVRI bands are presented in this paper. The observations, taken with the 82 cm IAC-80 telescope at Teide Observatory, Spain, were made from the beginning of 1996 February to 1998 July, as part of an ongoing lens-monitoring program. Accurate photometry was obtained by