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

Two-dimensional spectroscopy of the central 24^''x20^'' of the Seyfert 2 galaxy NGC 1068 has been obtained using a fiber-optic system (2D-FIS). The homogeneity, spectral coverage (~4170-5749 and 6250-9469 Å), and spatial (~0.9") and spectral resolution (~1.53 Å pixel^-1 and 2.73 Å pixel^-1) of the data make them a useful database with which to

La presencia de estructura espiral en galaxias (incluso antes de saber que las nebulosas eran objetos realmente extragalácticos) es uno de los temas que más interés ha despertado en la Astronomía. La teoría más famosa enunciada en los años 60 para explicar la presencia de esta estructura, la teoría de las ondas de densidad, no ha sido aún

We have computed the photometric magnitudes of rotating atmospheres-based on the simple model of Collins-for a grid suitable for main-sequence and slightly evolved stars of spectral type A0 to F5. A gravity-darkening law valid for radiative and convective envelopes has been considered. The general results are given as magnitude differences between

We present the results of a study of the star formation rates (SFRs) of a sample of disk galaxies in nearby compact groups compared with the SFRs of a sample of field galaxies. For this purpose, Hα luminosities and equivalent widths were derived for the galaxies of our sample. A direct comparison of the equivalent widths and Hα luminosities