Search Publications
4C +39.29 - extended emission around a powerful type 2 quasar
Fabian, A. C.; Gandhi, P.; Crawford, C. S.
We present new X-ray and optical spectroscopy of a type 2 quasar candidate selected from a follow-up programme of hard, optically dim, serendipitous Chandra sources. The source is confirmed to be a type 2 quasar at z = 0.536 with an intrinsic 2-10 keV luminosity L2-10 = 5 × 1044h-20.7 erg s-1,…
A statistical survey of the magnetotail current sheet
Balogh, A.; Zhang, T. L.; Nakamura, R. +8 more
Using Cluster magnetometer data during summer 2001 and 2002, when the spacecraft traversed the magnetotail, we have performed a survey of current sheet and its current. We applied a superposed epoch analysis to simple, monotonous current sheet crossings and obtained a statistical profile of the current sheet. We find that the averaged structure of…
Line Shape Changes and Doppler Measurements in Solar Active Regions. I. A Method for Correcting Dopplergrams from SOHO MDI
Schou, J.; Wachter, R.; Sankarasubramanian, K.
We present a method to correct MDI high-resolution Dopplergrams in active regions for systematic observational errors due to the spectral line shape changes. We use a measurement campaign with the Advanced Stokes Polarimeter to investigate the influence of line shape changes in active regions on MDI Dopplergram calibration. An estimate of the widt…
Seasonal evolution of Titan's dark polar hood: midsummer disappearance observed by the Hubble Space Telescope
Lorenz, Ralph D.; Lemmon, Mark T.; Smith, Peter H.
Titan, Saturn's largest moon, has a dense organic-laden atmosphere that displays dramatic seasonal variations in composition and appearance. Here we document the evolution of the dark polar hood, first seen in 1980 by Voyager 1 around the north pole, and report quantitative measurements of the hood's disappearance from the south pole in 2002-2003 …
Automated Detection of EUV Prominences
Foullon, C.; Verwichte, E.
We present methods to detect automatically off-limb prominences in the extreme ultraviolet (EUV), using synoptic images taken by the extreme-ultraviolet imaging telescope (EIT) on board SOHO. The 304 Å line is essential for the detection of EUV prominences, but the optimal detection is achieved through a combined image processing of the four synop…
Warm molecular gas in the envelope and outflow of IRAS 12496-7650 (DK Chamaeleontis)
van Dishoeck, E. F.; Schilke, P.; Güsten, R. +3 more
Aims.To obtain insight into the physical structure of the warm gas in the inner envelope of protostars and the interaction with the outflow.
Methods: .Sub-millimeter observations of 12CO, 13CO and/or C18O in J=3-2, J=4-3 and J=7-6 were obtained with the APEX Telescope towards IRAS 12496-7650, an intermediate ma…
Oxygen Abundance and Energy Deposition in the Slow Coronal Wind
Abbo, L.; Antonucci, E.; Telloni, D.
Observations of the extended corona obtained with the Ultraviolet Coronagraph Spectrometer (UVCS) on board the Solar and Heliospheric Observatory (SOHO) during the solar minimum years 1996 and 1997 have been analyzed to derive the oxygen abundance in the outer corona. A comparison of the absolute coronal abundance, measured in the coronal regions …
Cluster observation of plasma flow reversal in the magnetotail during a substorm
Livi, S.; Kistler, L. M.; Dunlop, M. W. +7 more
We investigate in detail a reversal of plasma flow from tailward to earthward detected by Cluster at the downstream distance of ~19 RE in the midnight sector of the magnetotail on 22 August 2001. This flow reversal was accompanied by a sign reversal of the Bz component and occurred during the late substorm expansion phase as …
Solar wind responses to the solar activity cycle
Marsch, Eckart
The solar magnetic field and the plasma properties, such as the temperature and density distributions in the solar corona, determine the solar wind stream structure and the extent and dynamics of the entire heliosphere, including its global magnetic field. The variation of the solar wind (coming in the form of steady fast streams, variable slow fl…
Rotation of the magnetic field in Earth's magnetosheath by bulk magnetosheath plasma flow
Lucek, E. A.; Schwartz, S. J.; Longmore, M.
Orientations of the observed magnetic field in Earth's dayside magnetosheath are compared with the predicted field line-draping pattern from the Kobel and Flückiger static magnetic field model. A rotation of the overall magnetosheath draping pattern with respect to the model prediction is observed. For an earthward Parker spiral, the sense of the …