Search Publications
Positron astronomy with SPI/INTEGRAL
Knödlseder, J.; Schanne, S.; Cordier, B. +7 more
We provide an overview of positron astronomy results that have been obtained using the INTEGRAL spectrometer SPI, and discuss their implications for the still mysterious origin of positrons in our Galaxy. It has long been known that the 511 keV positron annihilation emission is strongest from the central region of our Galaxy. Recently, it has been…
Survey of ELF-VLF plasma waves in outer radiation belt observed by Cluster STAFF-SA experiment
Cornilleau-Wehrlin, N.; Pokhotelov, D.; Lefeuvre, F. +1 more
Various types of plasma waves have profound effects on acceleration and scattering of radiation belt particles. For the purposes of radiation belt modeling it is necessary to know statistical distributions of plasma wave parameters. This paper analyzes four years of plasma wave observations in the Earth's outer radiation belt obtained by the STAFF…
Neon and oxygen in low activity stars: towards a coronal unification with the Sun
Schmitt, J. H. M. M.; Robrade, J.; Favata, F.
Aims: The disagreement between helioseismology and a recent downward revision of solar abundances has resulted in a controversy about the true neon abundance of the Sun and other stars. We study the coronal Ne/O abundance ratios of nearby stars with modest activity levels and investigate a possible peculiarity of the Sun among the stellar populati…
Formation of current density profile in tilted current sheets
Petrukovich, A. A.; Nakamura, R.; Baumjohann, W. +1 more
We investigate Cluster observations of strongly tilted sheets (flapping events) in the magnetotail. In accordance with the simple model of slip deformation (vertical differential displacement of neighboring flux tubes), the Jy current density component in the tilted sheet remains constant and equal to that in the horizontal undisturbed …
Why are CMEs large-scale coronal events: nature or nurture?
Mandrini, C. H.; van Driel-Gesztelyi, L.; Démoulin, P. +2 more
The apparent contradiction between small-scale source regions of, and large-scale coronal response to, coronal mass ejections (CMEs) has been a long-standing puzzle. For some, CMEs are considered to be inherently large-scale events eruptions in which a number of flux systems participate in an unspecified manner, while others consider magnetic reco…
The mid-infrared [SIV]/[NeII] versus [NeIII]/[NeII] correlation
Groves, Brent; Nefs, Bas; Brandl, Bernhard
The mid-infrared (MIR) ratio [NeIII]15.6µm/[NeII]12.8µm is a strong diagnostic of the ionization state of emission-line objects, due to its use of only strong neon emission lines only weakly affected by extinction. However, this ratio is not available to ground-based telescopes as only a few spectroscopic windows …
Color Gradients Detected in the HD 15115 Circumstellar Disk
Weinberger, Alycia J.; Debes, John H.; Song, Inseok
We report HST NICMOS coronagraphic images of the HD 15115 circumstellar disk at 1.1 µm. We find a similar morphology to that seen in the visible and at H band—an edge-on disk that is asymmetric in surface brightness. Several aspects of the 1.1 µm data are different, highlighting the need for multiwavelength images of each circumstellar…
Limb observations of the ultraviolet nitric oxide nightglow with SPICAV on board Venus Express
Bertaux, J. -L.; Villard, E.; Gérard, J. -C. +3 more
Limb observations of the spectrum of nightglow emission in the δ (190-240 nm) and γ (225-270 nm) bands of nitric oxide have been made with the Spectroscopy for Investigation of Characteristics of the Atmosphere of Venus (SPICAV) ultraviolet spectrometer on board Venus Express. These emissions arise from radiative recombination between O(3
Venus Doppler winds at cloud tops observed with ESPaDOnS at CFHT
Lellouch, Emmanuel; Widemann, Thomas; Donati, Jean-François
We present new wind measurements in Venus' lower mesosphere from visible spectroscopy during the 2007 worldwide coordinated ground campaign in support of ESA's Venus Express mission. These observations consisted of high-resolution spectra of Fraunhofer lines in the entire visible range (0.37-1.05 µm) to measure the winds near 68 km using the…
Suprathermal electron fluxes on the nightside of Mars: ASPERA-3 observations
Barabash, S.; Lundin, R.; Woch, J. +4 more
Recently aurora-type UV emissions were discovered on the nightside of Mars [Bertaux, J.-L., Leblanc, F., Witasse, O., et al., 2005. Discovery of an aurora on Mars. Nature 439, doi:10.1038/nature03603]. It was suggested that these emissions are produced by suprathermal electrons with energies of tens of eV, rather than by the electrons with spectra…