In response to our recent discovery of spiral arms in the accretion disc of IP Peg during rise to outburst, we have obtained time-resolved spectrophotometry of IP Peg during outburst maximum. In particular, indirect imaging of He II 4686, using Doppler tomography, shows a two-arm spiral pattern on the disc image, which confirms repeatability over

From an analysis of the spectrum (4000 Ä to 8800 Ä) of HD 101584 it is found that most of the neutral and single ionized metallic lines are in emission. The forbidden emission lines of [OI] 6300 Ä and 6363 Ä and [CI] 8727 Ä are detected, which indicate the presence of a very low excitation nebula. The Hα , FeII 6383 Ä, NaI D1, D2 lines and the CaII

We have obtained high- and intermediate-resolution optical spectra of the black hole candidate Nova Scorpii 1994 in 1998 May/June, when the source was in complete (X-ray) quiescence. We measure the radial velocity curve of the secondary star and obtain a semi-amplitude of K_2=215.5 +/- 2.4 km s^-1, which is 6 per cent lower than the only previously

New calculations of the Galactic contamination over microwave background radiation anisotropies are carried out. On the one hand, when a frequency-dependent contrast of molecular clouds with respect to the Galactic background of the diffuse interstellar medium is taken into account, the anisotropic amplitude produced by Galactic dust is increased

Ambiguity is shown in the context of the differential calculus of several variables and with the help of the language of category theory, a way to solve it in its most general form is offered. It is also shown that this new definition is related to other well-known definitions in the literature.

We have obtained for the first time K-band infrared spectra of the soft X-ray transient V616 Mon (=A0620-00). We determine the 2-sigma upper limit to the fraction of light arising from the accretion disc to be 27 percent. The effect this has on the binary inclination, determined from modelling the infrared ellipsoidal variations is to increase it