We present HST WFPC2 V and I images and GHRS UV spectrophotometry of the spectral regions around Lyα and OI λ1302 of the extremely metal-deficient ( Z ∼ Z⊙/41 ) blue compact dwarf (BCD) galaxy SBS 0335–052. All the star formation in the BCD occurs in six superstar clusters (SSC) with ages ≤ 3-4 Myr. As there is no evident sign of tidal interaction, star formation in the BCD is probably triggere...

We have analyzed GHRS data of eight Classical T Tauri stars (CTTSs) and one Weak T Tauri star (WTTS). The GHRS data consist of an spectral range 40 Å wide centered on 2800 Å. For 4 of the CTTS we have nearly simultaneous optical observations which contain Hα, Hβ, He I, NaD, and the Ca II infrared triplet. The Mg II resonance doublet is the strongest feature in the 2800 Å range. This line has a ...

We present new observations of the binary Sirius A / Sirius B performed with HST-GHRS. Two interstellar clouds are detected on this sightline, one of them being identified as the Local Interstellar Cloud (LIC), in agreement with previous HST-GHRS observations of Sirius A (Lallement et al. 1994). The interstellar structure of this sightline, which we assume is the same toward both stars (separat...

We present new observations of the binary Sirius A / Sirius B performed with HST-GHRS. Two interstellar clouds are detected on this sightline, one of them being identified as the Local Interstellar Cloud (LIC), in agreement with previous HST-GHRS observations of Sirius A (Lallement et al. 1994). The interstellar structure of this sightline, which we assume is the same toward both stars (separat...

The low-redshift IGM probes the last ten billion years of metal enrichment from galactic feedback processes. We present preliminary results from a survey of intergalactic metal-line absorption systems in archival HST STIS, GHRS, and FUSE spectra of ≈ 50 z . 2 UV-bright objects. We summarize the detailed analysis of one sightline (PKS1302–102, zQSO = 0.2784) with which we set the methodology for...

We present HST (WFPC2 and FOC) images and UV GHRS spectra plus ground-based optical spectra of four Luminous Infrared Galaxies (LIRGs) that have Seyfert 2 nuclei (Mrk 477, NGC 7130, NGC 5135 and IC 3639). The data provide direct evidence of the existence of a central nuclear starburst that dominates the UV and optical light and are dusty and compact. The bolometric luminosity (∼ 1010 L⊙) of the...

We present high-quality HST/GHRS spectra in the Hydrogen Lα spectral region of Vega and Sirius-A. Thanks to the signal-to-noise ratio achieved in these observations and to the similarity of the two spectra, we found clear evidence of emission features in the low flux region, λλ1190-1222Å. These emission lines can be attributed unambiguously to Fe ii and Cr ii transitions. In this spectral range...

I present results from recent ab-initio models for the formation and time-dependent behavior of outer atmospheric flows in α Ori (M2 Iab) produced by stochastic shock waves. Stochastic shocks are a natural consequence of acoustic energy generation due to stellar convection. Thewavemodels showdistinct episodes ofmomentum and energy deposition produced by strong shocks generated by merging of sho...