The optical disk is a computer-addressable binary storage medium with very high capacity. More than 1010 bits of information can be recorded on a 12-cm-diameter optical disk. The natural two-dimensional format of the data recorded on an optical disk makes this medium particularly attractive for the storage of images and holograms, while parallel access provides a convenient mechanism through wh...

Abstract. We present mass distributions obtained from near-infrared (NIR) surface brightness decompositions and rotation curve fitting of a sample of early-type spiral galaxies. Bulge and disk mass-to-light (M/L) ratios, dark halo parameters, and the modified Newtonian dynamics (MOND) acceleration parameter are derived. We find that the mean disk NIR M/L is higher than that of the bulge, and co...

Using a two-dimensional hydrodynamics code (PROMETHEUS), we explore the continued evolution of rotating helium stars, Mα >∼10 M⊙ , whose iron core collapse does not produce a successful outgoing shock, but instead forms a black hole of 2 3 M ⊙ . The model explored in greatest detail is the 14 M ⊙ helium core of a 35 M ⊙ main sequence star. The outcome is sensitive to the angular momentum. For j...

We present the results of the first mid-infrared interferometric observations of the Mira variable RR Sco with the MID-infrared Interferometer (MIDI) coupled to the European Southern Observatory’s (ESO) Very Large Telescope Interferometer (VLTI), together with K-band observations using the VLTI commissioning instrument VINCI. The observations were carried out in June 2003, when the variability ...

A detailed study of nearby, morphologically normal Sa galaxies reveals that about half show some spectrocopic evidence for kinematically distinct components despite their undisturbed optical appearance. In eight of nine objects mapped in the 21 cm HI line, the HI distribution extends far outside the optical disk and warps of the HI disk are complex. The multiwavelength evidence can be interpret...

Context. Asteroid (130) Elektra belongs to one of the six known triple asteroids in the main belt, so its mass has been reliably determined. Aims. We aim to use all available disk-resolved images of (130) Elektra obtained by the SPHERE instrument at VLT and by the Nirc2 of the Keck telescope together with the disk-integrated photometry to determine its shape model and its size. The volume can b...

The infall of a satellite galaxy onto a galactic disk generally brings in angular momentum that is not aligned with the axis of the disk. The main dynamical issues addressed are what fraction of the orbital angular momentum of the satellite and the associated energy is added to the disk, as opposed to being left in the halo, and whether the absorbed fraction is added coherently or thermalized i...

Context. HH 30 is a well-known Pre-Main-Sequence star in Taurus. HST observations have revealed a flared, edge-on disk driving a highly-collimated optical jet, making this object a case study for the disk-jet-outflow paradigm. Aims. We searched for a molecular outflow, and attempted to better constrain the star and disk parameters. Methods. We obtained high angular resolution (∼ 1′′) observatio...

We present the first resolved study of the radio continuum properties of I Zw18, the dwarf galaxy with the lowest known nebular metal abundance in the local universe. New Very Large Array radio continuum images at 20 and 3.6 cm are compared to various Hubble Space Telescope images, and we find a striking morphological similarity between high resolution Hα and short wavelength radio continuum em...

Disk and wind signatures are seen in the soft state of Galactic black holes, while the jet is seen in the hard state. Here we study the disk-wind connection in the ρ class of variability in GRS 1915+105 using a joint NuSTAR-Chandra observation. The source shows 50 sec limit cycle oscillations. By including new information provided by the reflection spectrum, and using phase-resolved spectroscop...