Search Publications
Energy input from the exterior cusp into the ionosphere: Correlated ground-based and satellite observations
Fazakerley, A. N.; André, M.; Réme, H. +7 more
The energy transport from the exterior cusp into the ionosphere is investigated using coordinated ground-based (EISCAT and MIRACLE) and satellite (Cluster) observations. EISCAT and MIRACLE data are used to estimate the plasma heating in the F-region and the Joule heating in the E-region. Cluster measurements are used to derive the electromagnetic …
The ISOPHOT 170 µm Serendipity Survey. IV. The far-infrared sky atlas
Krause, O.; Lemke, D.; Klaas, U. +1 more
Aims:To further increase the scientific utilization of the strip scanning measurements of the ISOPHOT Serendipity Survey (ISOSS), the slew data has been assembled to a sky atlas with ≈15% sky coverage in the hitherto unobserved far-infrared wavelength band around 170 µm.
Methods: The redundant information of the brightnesses at slew cros…
The solar radius in the EUV during the cycle XXIII
Giménez de Castro, C. G.; Varela Saraiva, A. C.; Costa, J. E. R. +1 more
Aims:We aim to determine the solar transition region and coronal radius at EUV wavelengths and its time evolution during Solar Cycle XXIII.
Methods: We use daily 30.4 and 17.1 nm images obtained by the Extreme Ultraviolet Imager (EIT) aboard the SoHO satellite and derive the solar radius by fitting a circle to the limb brightness ring.
Res…
Tracking the edge of the south seasonal polar cap of Mars
Grassi, D.; Formisano, V.; Giuranna, M. +1 more
The advance and retreat of the polar caps were one of the first observations that indicated Mars had seasons. Because a large portion of the atmosphere is cycled in and out of the seasonal caps during the year, the frost deposits play a significant role in regional and global atmospheric circulation. Understanding the nature of the seasonal polar …
Small-Scale Energy Release Driven by Supergranular Flows on the Quiet Sun
Potts, H. E.; Diver, D. A.; Khan, J. I.
We present data and modelling for the quiet Sun that strongly suggest a ubiquitous small-scale atmospheric heating mechanism that is driven solely by converging supergranular flows. A possible energy source for such events is the power transfer to the plasma via the work done on the magnetic field by photospheric convective flows, which exert drag…
Reconstruction of the reconnection rate from Cluster measurements: Method improvements
Farrugia, C. J.; Penz, T.; Nakamura, R. +7 more
A remote-sensing method for reconstructing the reconnection rate and the location of X-line from single-spacecraft observations developed recently is extended to a compressible plasma and an asymmetric magnetic field configuration. The method is based on the two-dimensional analytical model of time-dependent Petschek-type magnetic reconnection. Th…
Broadening of Resonantly Scattered Ultraviolet Emission Lines by Coronal Hole Outflows
Akinari, Nakagawa
Measurements by the Ultraviolet Coronagraph Spectrometer on board the Solar and Heliospheric Observatory have revealed that the widths of several ultraviolet emission lines are unexpectedly large in solar coronal holes. Here we investigate the line-broadening mechanisms for resonantly scattered emissions, which constitute the major part of the cor…
Oscillation of Venus' upper atmosphere
Forbes, J. M.; Konopliv, A.
Little is known about the variability of Venus' upper atmosphere. We report discovery of a large (~ +/-30-50%) 9-day period density oscillation, derived from radar tracking of the Magellan spacecraft from 15 Sept 92 - 24 May 93. The densities correspond to 164-184 km altitude, 11°N latitude, and cover all local times. The wave is presumed to propa…
Hubble Space Telescope Ultraviolet Spectroscopy of 14 Low-Redshift Quasars
Kaiser, Mary Elizabeth; Laor, Ari; Hall, Patrick B. +35 more
We present low-resolution ultraviolet spectra of 14 low-redshift (zem<~0.8) quasars observed with the Hubble Space Telescope STIS as part of a Snapshot project to understand the relationship between quasar outflows and luminosity. By design, all observations cover the C IV emission line. Ten of the quasars are from the Hamburg-ESO ca…
IGR J17497-2821 : a new X-ray nova
Paltani, S.; Gehrels, N.; Walter, R. +8 more
Context: A new hard X-ray transient has been discovered by INTEGRAL on 2006 Sep. 17 at 1 degree from the Galactic Centre.
Aims: INTEGRAL, Swift/XRT and optical photometric observations are used to characterize
Methods: The X-ray position has been refined to arcsec level through a…