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Binary and Multiple O-Type Stars in the Cassiopeia OB6 Association
Gies, Douglas R.; Bagnuolo, William G., Jr.; McSwain, M. Virginia +3 more
We present the results of time-resolved spectroscopy of 13 O-type stars in the Cas OB6 stellar association. We conducted a survey for radial velocity variability in search of binary systems, which are expected to be plentiful in young OB associations. Here we report the discovery of two new single-lined binaries, and we present new orbital element…
Observations of Vertical Reflections from the Topside Martian Ionosphere
Gurnett, D. A.; Morgan, D. D.; Orosei, R. +7 more
The Martian ionosphere has for the first time been probed by a low frequency topside radio wave sounder experiment (MARSIS) (Gurnett et al., 2005). The density profiles in the Martian ionosphere have for the first time been observed for solar zenith angles less than 48 degrees. The sounder spectrograms typically have a single trace of echoes, whic…
SPICAM IR acousto-optic spectrometer experiment on Mars Express
Gondet, B.; Grigoriev, A.; Bertaux, Jean-Loup +14 more
The SPICAM IR spectrometer on Mars Express mission (1.0-1.7 µm, spectral resolution 0.5-1.2 nm) is dedicated primarily to nadir measurements of H2O abundance. It is one of two channels of SPICAM UV-IR instrument. In this spectrometer we applied for the first time in planetary research the technology of an acousto-optic tunable fil…
High-redshift Faranoff-Riley type II radio galaxies: X-ray properties of the cores
Hardcastle, M. J.; Worrall, D. M.; Belsole, E.
We present an extensive X-ray spectral analysis of the cores of 19 Faranoff-Riley type II sources in the redshift range 0.5 < z < 1.0 which were selected to be matched in isotropic radio power. The sample consists of 10 radio galaxies (RGs) and nine quasars. We compare our results with the expectations from a unification model that ascribes …
Type II Quasars from the Sloan Digital Sky Survey. IV. Chandra and XMM-Newton Observations Reveal Heavily Absorbed Sources
Strauss, Michael A.; Schneider, Donald P.; Heckman, Timothy M. +4 more
We are carrying out sensitive X-ray observations with Chandra and XMM-Newton of type II quasars selected from the Sloan Digital Sky Survey based on their optical emission line properties. In this paper we present the first results of our program. We present observations of four objects at redshifts 0.4<z<0.8, and an analysis of the archival …
Enceladus' Varying Imprint on the Magnetosphere of Saturn
Krupp, N.; Woch, J.; Dougherty, M. K. +6 more
The bombardment of Saturn's moon Enceladus by >20-kiloelectron volt magnetospheric particles causes particle flux depletions in regions magnetically connected to its orbit. Irrespective of magnetospheric activity, proton depletions are persistent, whereas electron depletions are quickly erased by magnetospheric processes. Observations of these …
Ultraviolet-to-far infrared properties of Lyman break galaxies and luminous infrared galaxies at z ~ 1
Ilbert, O.; Buat, V.; Burgarella, D. +13 more
Aims.We present the first large, unbiased sample of Lyman Break Galaxies (LBGs) at z ∼ 1. Far ultraviolet-dropout (1530 Å) galaxies in the Chandra Deep Field South have been selected using GALEX data. This first large sample in the z ∼ 1 universe provides us with a high quality reference sample of LBGs.
Methods: .We analyzed the sample from t…
Cassini CIRS retrievals of ammonia in Jupiter's upper troposphere
Achterberg, Richard K.; Conrath, Barney J.; Gierasch, Peter J.
The zonal mean ammonia abundance on Jupiter between the 400- and 500-mbar pressure levels is inferred as a function of latitude from Cassini Composite Infrared Spectrometer data. Near the Great Red Spot, the ammonia abundance is mapped as a function of latitude and longitude. The Equatorial Zone is rich in ammonia, with a relative humidity near un…
What is the spatial distribution of magnetic helicity injected in a solar active region?
Démoulin, P.; Pariat, E.; Nindos, A. +1 more
Context: .Magnetic helicity is suspected to play a key role in solar phenomena such as flares and coronal mass ejections. Several investigations have recently computed the photospheric flux of magnetic helicity in active regions. The derived spatial maps of the helicity flux density, called G_A, have an intrinsic mixed-sign patchy distribution.
Dynamical Evolution of the TW Hydrae Association
Ortega, V. G.; de la Reza, R.; Jilinski, E.
Using Galactic dynamics we have determined the age of the low-mass post-T Tauri stars in the TW Hya Association (TWA). To do so we applied the method of Ortega and coworkers to five stars of the association with Hipparcos-measured distances (TWA 1, TWA 4, TWA 9, TWA 11, and TWA 19). The method is based on the calculation of the past three-dimensio…