Search Publications

Cosmic evolution of the galaxy's mass and luminosity functions by morphological type from multi-wavelength data in the CDF-South

Berta, S.; Rodighiero, G.; Hatziminaoglou, E. +7 more

Aims.We constrain the evolution of the galaxy mass and luminosity functions from the analysis of (public) multi-wavelength data in the Chandra Deep Field South (CDFS) area, obtained from GOODS and other projects, including very deep high-resolution imaging by HST/ACS.
Methods.Our reference catalogue of faint high-redshift galaxies, which we hav…

The dynamics behind Titan's methane clouds

Mitchell, J. L.; Pierrehumbert, R. T.; Frierson, D. M. W. +1 more

A Hubble Space Telescope Archival Survey of Feathers in Spiral Galaxies

Ostriker, Eve C.; La Vigne, Misty A.; Vogel, Stuart N.

We present a survey of spiral arm extinction substructures referred to as feathers in 223 spiral galaxies using Hubble Space Telescope WFPC2 images. The sample includes all galaxies in the RC3 catalog with cz<5000 km s^-1, B_T<15, i<60^deg, and types Sa-Sd with well-exposed broadband WFPC2 images. The detecti…

Comparisons between MHD model calculations and observations of Cassini flybys of Titan

Dougherty, Michele K.; Hansen, Kenneth C.; Sokolov, Igor V. +6 more

The Cassini spacecraft passed by Titan on 26 October 2004 (Ta flyby) and 13 December 2004 (Tb flyby). In both cases the Cassini Orbiter entered Titan's ionosphere and flew through Titan's dynamic wake region. In this paper, we present our simulation results of these two flybys using our three-dimensional multispecies MHD model. This model is a sli…

Cosmic Rays at High Heliolatitudes

Potgieter, M. S.; Heber, B.

The Ulysses spacecraft has been the first to orbit the Sun over its poles and to explore the heliosphere at these high heliolatitudes. It has now completed two fast latitude scans, one at solar minimum and one at solar maximum. Since its launch in October 1990, this mission has led to several surprising discoveries concerning energetic particles, …

Evolution of magnetic fields and energetics of flares in active region 8210

Régnier, S.; Canfield, R. C.

To better understand eruptive events in the solar corona, we combine sequences of multi-wavelength observations and modelling of the coronal magnetic field of NOAA AR 8210, a highly flare-productive active region. From the photosphere to the corona, the observations give us information about the motion of magnetic elements (photospheric magnetogra…

Average hard X-ray emission from NS LMXBs: observational evidence of different spectral states in NS LMXBs

Titarchuk, L.; Frontera, F.; Goldoni, P. +9 more

Aims.We studied and compared the long-term average hard X-ray (>20 keV) spectra of a sample of twelve bright low-mass X-ray binaries hosting a neutron star (NS). Our sample comprises the six well studied Galactic Z sources and six Atoll sources, four of which are bright (“GX”) bulge sources while two are weaker ones in the 2-10 keV range (H 175…

Young star cluster complexes in NGC 4038/39. Integral field spectroscopy using VIMOS-VLT

Bastian, N.; Maraston, C.; Kissler-Patig, M. +1 more

We present the first results of a survey to obtain Integral Field Spectroscopy of merging galaxies along the Toomre Sequence. In the present work, we concentrate on the star cluster complexes in the Antennae galaxies (NGC 4038/39) in the overlap region as well as the nuclear region of NGC 4038. Using optical spectroscopy we derive the extinction, …

Proper Motions of Dwarf Spheroidal Galaxies from Hubble Space Telescope Imaging. IV. Measurement for Sculptor

Minniti, Dante; Mateo, Mario; Piatek, Slawomir +5 more

This article presents a measurement of the proper motion of the Sculptor dwarf spheroidal galaxy determined from images taken with the Hubble Space Telescope using the Space Telescope Imaging Spectrograph in the imaging mode. Each of two distinct fields contains a quasi-stellar object that serves as the ``reference point.'' The measured proper mot…

Properties of O VI Absorption in the Local Interstellar Medium

Savage, Blair D.; Lehner, Nicolas

The measurement of absorption over short distances in the local interstellar medium (LISM) provides an excellent opportunity to study the properties of O VI absorption and its kinematic relationship to absorption by tracers of cool and warm gas. We report on the properties of LISM O VI absorption observed with 20 km s^-1 resolution Far U…