Search Publications
Do BBFs contribute to inner magnetosphere dipolarizations: Concurrent Cluster and Double Star observations
Zhang, T. L.; Klecker, B.; Nakamura, R. +7 more
We examined the relationship between bursty bulk flow (BBF) events observed by Cluster between -19 RE < X < -12 RE and dipolarization events observed by Double Star TC1 between -13 RE < X < -6 RE. TC1 observed dipolarizations for ~33% of the cases when BBFs were observed by Cluster. During th…
Two Successive Coronal Mass Ejections Driven by the Kink and Drainage Instabilities of an Eruptive Prominence
Zhang, J.; Chen, P. F.; Wang, J. X. +3 more
We describe a clear case of the initiation of a propagating bright arc and a CME on 2002 December 28, which were associated with an eruptive prominence. In EIT 304 and 195 Å images, a very long filament showed evidence of severe twisting in one of its fragments, which appeared as a prominence on December 26; then, the prominence showed the convers…
FUSE and HST STIS Far-Ultraviolet Observations of AM Herculis in an Extended Low State
Hubeny, Ivan; Gänsicke, Boris T.; Long, Knox S. +1 more
We have obtained FUSE and HST STIS time-resolved spectroscopy of the Polar AM Herculis during a deep low state. The spectra are entirely dominated by the emission of the white dwarf. Both the far-ultraviolet (FUV) flux and the spectral shape vary substantially over the orbital period, with maximum flux occurring at the same phase as during the hig…
Energy-dependent variability and the origin of the soft X-ray excess in active galactic nuclei
Done, Chris; Gierliński, Marek
The origin of the soft excess seen in many active galactic nuclei (AGN) below ~1 keV is still an unsolved problem. It is unlikely to represent a true continuum component as its characteristic `temperature' shows a remarkable constancy over a wide range of AGN luminosity and black hole mass. This instead favours an association with atomic processes…
Probing the evolution of the near-infrared luminosity function of galaxies to z~= 3 in the Hubble Deep Field-South
Chincarini, G.; Fontana, A.; Vanzella, E. +6 more
We present the rest-frame Js- and Ks-band luminosity function (LF) of a sample of about 300 galaxies selected in the Hubble Deep Field-South (HDF-S) at Ks<= 23 (Vega). We use calibrated photometric redshift together with spectroscopic redshift for 25 per cent of the sample. The accuracy reached in the photometri…
Quasar Spectrum Classification with Principal Component Analysis (PCA): Emission Lines in the Lyα Forest
Suzuki, Nao
We investigate the variety in quasar UV spectra (λλ1020-1600), with emphasis on the weak emission lines in the Lyα forest region, using principal component analysis (PCA). We use 50 smooth continuum-fitted quasar spectra (0.14<z<1.04) taken by the Hubble Space Telescope (HST) Faint Object Spectrograph. The first, second, and third principal …
X-ray observations of RX J0822-4300 and Puppis-A
Hui, C. Y.; Becker, W.
Based on observations with the X-ray observatories Chandra and XMM-Newton we present results from a detailed spectro-imaging and timing analysis of the central compact X-ray source RX J0822-4300 in the supernova remnant Puppis-A. The superior angular resolution of Chandra allows for the first time to pinpoint the point source nature of this object…
An improved deprojection and PSF-deconvolution technique for galaxy-cluster X-ray surface-brightness profiles
Arnaud, M.; Pointecouteau, E.; Pratt, G. W. +1 more
We have developed a regularisation procedure for the direct deprojection and PSF-deconvolution of X-ray surface brightness profiles of clusters of galaxies. This procedure allows us to obtain accurate density profiles in a straightforward manner from X-ray observations (in particular data from XMM-Newton, where the PSF correction is important), wh…
Vertical distribution of ozone on Mars as measured by SPICAM/Mars Express using stellar occultations
Montmessin, Franck; Bertaux, Jean-Loup; Perrier, Séverine +4 more
The ultraviolet spectrometer of the SPICAM instrument on board the European Mars Express mission has performed stellar occultations to probe the atmosphere. Vertical profiles of ozone are retrieved from inversion of transmission spectra in the altitude range 20-30 to 70 km. They are analyzed here as functions of latitude and season of the observat…
The evolution of Lyman α absorbers in the redshift range 0.5 < z < 1.9
Reimers, D.; Janknecht, E.; Lopez, S. +1 more
We investigate the evolution and the statistical properties of the Ly α absorbers of the intergalactic medium (IGM) in the largely unexplored redshift range z=0.5-1.9. We use high-resolution (R ≥ 30 000) UV (STIS) and optical (VLT/UVES and Keck/HIRES) spectra of nine bright quasars with z_em < 1.94. The Ly α lines detected in the lines of sight…