Search Publications
A new perspective on quiet Sun magnetism
Lites, Bruce William
The Hinode mission has provided us with a new, quantitative view of the magnetism of the quiet Sun. It has revealed that the quiet internetwork areas are blanketed by horizontal fields that appear at first sight to have more flux than the vertical fields resolved on the same 0.3″ size scale. These measurements point to the possibility that the hor…
Cluster observations of energetic electron flux variations within the plasma sheet
Dandouras, I.; McPherron, R. L.; Baker, D. N. +3 more
The variability of energetic electron fluxes (>40 keV) within the plasma sheet is explored using measurements from the Cluster spacecraft from 2001 through 2005. Only cases where the spacecraft remains inside the plasma sheet throughout the event are considered. Interesting cases were found using a combination of automated methods and visual in…
Dual source populations of substorm-associated ring current ions
Yamauchi, M.; Dandouras, I.; Rème, H. +1 more
Sources of low-energy ring current ions in the early morning sector (eastward drifting energy domain of about <5 keV) are examined using both statistical analyses and numerical tracing methods (phase-space mapping and simulation). In about 90% of Cluster perigee traversals at 02~07 local time, these low-energy ring current ions have dual ion po…
Variable Intrinsic Absorption in Mrk 279
Scott, Jennifer E.; Kriss, Gerard A.; Quijano, Jessica Kim +5 more
We examine the variability in the intrinsic absorption in the Seyfert 1 galaxy Mrk 279 using three epochs of observations from the Far Ultraviolet Spectroscopic Explorer and two epochs of observations with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope. Rather than finding simple photoionization responses of the absorbing g…
The VOISE algorithm: a versatile tool for automatic segmentation of astronomical images
Achilleos, N.; Guio, P.
The auroras on Jupiter and Saturn can be studied with a high sensitivity and resolution by the Hubble Space Telescope (HST) ultraviolet (UV) and far-ultraviolet Space Telescope Imaging Spectrograph (STIS) and Advanced Camera for Surveys (ACS) instruments. We present results of automatic detection and segmentation of Jupiter's auroral emissions as …
Scale size and life time of energy conversion regions observed by Cluster in the plasma sheet
Dandouras, I.; Hamrin, M.; Norqvist, P. +4 more
In this article, and in a companion paper by Hamrin et al. (2009) [Occurrence and location of concentrated load and generator regions observed by Cluster in the plasma sheet], we investigate localized energy conversion regions (ECRs) in Earth's plasma sheet. From more than 80 Cluster plasma sheet crossings (660 h data) at the altitude of about 15-…
Electric Fields and Magnetic Fields in the Plasmasphere: A Perspective From CLUSTER and IMAGE
de Keyser, Johan; Carpenter, Donald L.; Darrouzet, Fabien +7 more
The electric field and magnetic field are basic quantities in the plasmasphere measured since the 1960s. In this review, we first recall conventional wisdom and remaining problems from ground-based whistler measurements. Then we show scientific results from Cluster and Image, which are specifically made possible by newly introduced features on the…
Synchronization mechanism of sharp edges in rings of Saturn
Spahn, F.; Schmidt, J.; Shepelyansky, D. L. +1 more
We propose a new mechanism which explains the existence of enormously sharp edges in the rings of Saturn. This mechanism is based on the synchronization phenomenon due to which the epicycle rotational phases of particles in the ring, under certain conditions, become synchronized with the phase of external satellite, e.g. with the phase of Mimas in…
HST observations of the nebula around the central compact object in the Vela Jr. supernova remnant
de Luca, A.; Pellizzoni, A.; Mignani, R. P.
Context: A handful of young (a few thousand years) supernova remnants (SNRs) host point-like X-ray sources, dubbed central compact objects (CCOs), which are thought to be radio-silent isolated neutron stars formed by the supernova explosion. So far, no CCO has been firmly detected at other wavelengths. However, ground-based observation in the Hα b…
AKARI Far-Infrared Spectroscopic Observations of the Galactic Center Region
Takahashi, H.; Nakagawa, T.; Okada, Y. +5 more
We have observed the Quintuplet- and Arches-cluster regions with the Fourier Transform Spectrometer (FTS) of the Far-Infrared Surveyor (FIS) aboard AKARI to investigate the physical conditions of interstellar matter around the clusters. The FIS-FTS mapping data reveal differences in the spatial distribution among the far-infrared [OIII], [NII], an…