Search Publications
On the origin of gypsum in the Mars north polar region
Bibring, Jean-Pierre; Langevin, Yves; Poulet, François +2 more
We describe the distribution and concentration of the largest Martian gypsum deposit discovered to date by the Mars Express OMEGA (Observatoire pour le Mineralogie, l'Eau, les Glaces et l'Activité) imaging spectrometer, its relationship to the late Amazonian-aged north polar dunes in which it is found, and its likely origin. Gypsum has not been di…
The UDF05 Follow-up of the Hubble Ultra Deep Field. I. The Faint-End Slope of the Lyman Break Galaxy Population at z ~ 5
Panagia, N.; Gardner, Jonathan P.; Ferguson, H. C. +14 more
We present the UDF05 HST program, which consists of three disjoint fields-NICP12, NICP34, plus the HUDF-with deep ACS (F606W, F775W, and F850LP) and NICMOS (F110W and F160W) imaging. Here we use the ACS data for the NICP12 and HUDF fields to implement a (V-i)-(i-z) selection criterion that allows us to identify a sample of 101 (133) z~5 Lyman brea…
The structure of Venus' middle atmosphere and ionosphere
Pätzold, M.; Bird, M. K.; Asmar, S. W. +8 more
The atmosphere and ionosphere of Venus have been studied in the past by spacecraft with remote sensing or in situ techniques. These early missions, however, have left us with questions about, for example, the atmospheric structure in the transition region from the upper troposphere to the lower mesosphere (50-90km) and the remarkably variable stru…
Multispacecraft Measurement of Anisotropic Correlation Functions in Solar Wind Turbulence
Horbury, T. S.; Osman, K. T.
Multispacecraft measurements in the solar wind are used to determine the field-aligned anisotropy of magnetohydrodynamic inertial range turbulence. The ratio of the parallel to perpendicular correlation lengths is measured by using time-lagged two-point correlations to construct a spatial autocorrelation function. The mean ratio obtained, 1.79+/-0…
South-polar features on Venus similar to those near the north pole
Baines, K. H.; Langevin, Y.; Lopez-Valverde, M. A. +102 more
Venus has no seasons, slow rotation and a very massive atmosphere, which is mainly carbon dioxide with clouds primarily of sulphuric acid droplets. Infrared observations by previous missions to Venus revealed a bright `dipole' feature surrounded by a cold `collar' at its north pole. The polar dipole is a `double-eye' feature at the centre of a vas…
The Intrinsically X-Ray-weak Quasar PHL 1811. II. Optical and UV Spectra and Analysis
Jenkins, Edward B.; Halpern, Jules P.; Leighly, Karen M. +1 more
This is the second of two papers reporting observations and analysis of the unusually bright (mb=14.4), luminous (MB=-25.5), nearby (z=0.192) narrow-line quasar PHL 1811. The first paper reported that PHL 1811 is intrinsically X-ray-weak and presented a spectral energy distribution (SED). Here we present HST STIS optical and …
The Globular Cluster Luminosity Function and Specific Frequency in Dwarf Elliptical Galaxies
Miller, Bryan W.; Lotz, Jennifer M.
The globular cluster luminosity function, specific globular cluster frequency, SN, specific globular cluster mass, TMP, and globular cluster mass fraction in dwarf elliptical galaxies are explored using the full 69 galaxy sample of the HST WFPC2 Dwarf Elliptical Galaxy Snapshot Survey. The GCLFs of the dEs are well represente…
X-ray precursors to flares and filament eruptions
Mason, H. E.; Dennis, B. R.; Tripathi, D. +1 more
Aims:To study preflare X-ray brightenings as diagnostics of the destabilisation of flare-associated erupting filaments/prominences.
Methods: We combine new observations from the Transition Region and Coronal Explorer (TRACE) and the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI), as well as revisit events reported in the literat…
Martian water vapor: Mars Express PFS/LW observations
Forget, F.; Montmessin, F.; Lellouch, E. +8 more
We present the seasonal and geographical variations of the martian water vapor monitored from the Planetary Fourier Spectrometer Long Wavelength Channel aboard the Mars Express spacecraft. Our dataset covers one martian year (end of Mars Year 26, Mars Year 27), but the seasonal coverage is far from complete. The seasonal and latitudinal behavior o…
Star Formation via the Little Guy: A Bayesian Study of Ultracool Dwarf Imaging Surveys for Companions
Allen, Peter R.
I have undertaken a comprehensive statistical investigation of the ultracool dwarf companion distribution (spectral type M6 and later). Utilizing a Bayesian algorithm, I tested models of the companion distribution against data from an extensive set of space and ground-based imaging observations of nearby ultracool dwarfs. My main conclusions are f…