A b s tra c t. -We present an atlas of very high resolution (R ~ 50000) Hα line profiles of 63 pre-main sequence stars, divided among 43 T Tauri stars, 18 Herbig Ae/Be stars, and 2 FU Orionis objects. Ha emission is the most common and prominent spectroscopic feature of pre-main sequence stars, and although it is optically very thick it is still the most frequently modelled emission line in young stars. In T Tauri stars the principal models involve magnetically driven winds, and more recently the role of infalling magnetospheric material has been explored. For Herbig Ae/Be stars a variety of models have been proposed, current emphasis is directed towards obscuration by clumpy circumstellar disk structures. In order to provide constraints on such models, we have made a statistical analysis of the 63 high resolution profiles. We here ignore the considerable variability of the Ha emission, which is discussed in detail in a second paper. Most of our observed lines show complex profiles due to an interplay between emission and absorption features, and we suggest a two-dimensional classification scheme to describe these line profiles, based on the relative height of a secondary peak to the primary peak, as well as whether the absorption is blue-or red-shifted. Among T Tauri stars, 25% have symmetric profiles, 49% have blueshifted absorption dips, and 5% have P Cygni profiles; the remaining 21% show a variety of redshifted absorptions. For Herbig Ae/Be stars symmetric lines are quite rare (11%), indeed almost all of these stars have deep and prominent central absorptions. We have measured the extent of the line wings for all of our stars at the I max/40 level, and find that almost all have very extended wings, with typical extents of ±350 km/s, but in high S /N spectra the wings can be traced to lower intensities, and velocities as high as ±900 km/s have been observed. Pronounced asymmetries of these extended wings are found for many stars, suggesting the possibility that the highest velocity material could be non-uniformly distributed. The equivalent widths of the Ha emission in our sample of stars span two orders of magnitude, with a distribution that increases with decreasing equivalent width.

A B S T R A C TWe present contemporaneous optical and infrared (IR) photometric observations of the Type IIn SN 1998S covering the period between 11 and 146 d after discovery. The IR data constitute the first ever IR light curves of a Type IIn supernova. We use blackbody and spline fits to the photometry to examine the luminosity evolution. During the first 2±3 months, the luminosity is dominated by the release of shock-deposited energy in the ejecta. After ,100 d the luminosity is powered mostly by the deposition of radioactive decay energy from 0X150X05 M ( of 56 Ni which was produced in the explosion. We also report the discovery of an astonishingly high IR excess, K 2 L H 2X5Y that was present at day 130. We interpret this as being due to thermal emission from dust grains in the vicinity of the supernova. We argue that to produce such a high IR luminosity so soon after the explosion, the dust must be preexisting and so is located in the circumstellar medium of the progenitor. The dust could be heated either by the UV/optical flash (IR echo) or by the X-rays from the interaction of the ejecta with the circumstellar material.

Apesar de o Brasil ser um país rico em geodiversidade existe uma carência de estudos e metodologias de inventariação e quantificação tanto sobre a geodiversidade quanto do patrimônio geomorfológico e da geoconservação. Nesse sentido, este trabalho tem como objetivo fazer uma revisão sobre os conceitos de Geodiversidade, Patrimônio Geomorfológico e Geoconservação e discutir sobre a difusão e os caminhos a serem seguidos por esse tipo de estudo no Brasil. A metodologia utilizada envolveu uma ampla revisão bibliográfica pertinente à temática (livros, dissertações, teses e artigos) como, por exemplo, os trabalhos de Stanley (2000); Gray (2005); Brilha (2005); Pereira (2006), dentre outros.