Search Publications
Multi-resolution topographic data extraction from Martian stereo imagery
Muller, J. -P.; Kim, J. R.
The acquisition of high resolution topographic data such as Digital Terrain Models (DTMs) and orthoimages from various Martian stereo imagery is now readily available. The very successful European Space Agency (ESA) Mars Express mission includes the High Resolution Stereo Camera (HRSC) which has provided, since March 2004, an increasingly global s…
Numerical Models of Travel-Time Inhomogeneities in Sunspots
Moradi, H.; Hanasoge, S. M.; Cally, P. S.
We investigate the direct contribution of strong, sunspot-like magnetic fields to helioseismic wave travel-time shifts via two numerical forward models, a three-dimensional ideal MHD solver and MHD ray theory. The simulated data cubes are analyzed using the traditional time-distance center-to-annulus measurement technique. We also isolate and anal…
Plasma environment of Venus: Comparison of Venus Express ASPERA-4 measurements with 3-D hybrid simulations
Barabash, S.; Lundin, R.; Krupp, N. +13 more
We use data of the ASPERA-4 ion and electron spectrometers onboard Venus Express to determine the locations and shapes of the plasma boundaries (bow shock, ion composition boundary, and mantle) at Venus. We also investigate the variation of the terminator bow shock position as a function of the solar wind dynamic pressure and solar EUV flux. We co…
Detection of a Companion Lens Galaxy Using the Mid-Infrared Flux Ratios of the Gravitationally Lensed Quasar H1413+117
Kochanek, Christopher S.; Agol, Eric; MacLeod, Chelsea L.
We present the first resolved mid-infrared (IR) (11 µm) observations of the four-image quasar lens H1413+117 using the Michelle camera on Gemini North. All previous observations (optical, near-IR, and radio) of this lens show a "flux anomaly," where the image flux ratios cannot be explained by a simple, central lens galaxy. We attempt to rep…
Observation of bipolar moving magnetic features streaming out from a naked spot
Guglielmino, S. L.; Romano, P.; Zuccarello, F. +5 more
Context: Mechanisms responsible for active-region formation, evolution, and decay have been investigated by many authors and several common features have been identified. In particular, a key element in the dispersal of the magnetic field seems to be the presence of magnetic elements, called moving magnetic features (MMFs).
Aims: We analyze th…
Suzaku Observation of the New Soft Gamma Repeater SGR 0501+4516 in Outburst
Sakamoto, T.; Tiengo, A.; Hurley, K. +17 more
We present the first Suzaku observation of the new Soft Gamma Repeater, SGR 0501+4516, performed on 2008 August 26, four days after the onset of bursting activity of this new member of the magnetar family. The soft X-ray persistent emission was detected with the X-ray Imaging Spectrometer (XIS) at a 0.5-10 keV flux of 3.8 × 10-11 erg s<…
On the Absence of Photospheric Net Currents in Vector Magnetograms of Sunspots Obtained from Hinode (Solar Optical Telescope/Spectro-Polarimeter)
Tiwari, Sanjiv Kumar; Venkatakrishnan, P.
Various theoretical and observational results have been reported regarding the presence/absence of net electric currents in the sunspots. The limited spatial resolution of the earlier observations perhaps obscured the conclusions. We have analyzed 12 sunspots observed from Hinode (Solar Optical Telescope/Spectro-polarimeter) to clarify the issue. …
Comparison of Hinode/XRT and RHESSI Detection of Hot Plasma in the Non-Flaring Solar Corona
Testa, Paola; Reale, Fabio; McTiernan, James M.
We compare observations of the non-flaring solar corona made simultaneously with Hinode/XRT and RHESSI. The analyzed corona is dominated by a single active region on 2006 November 12. The comparison is made on emission measures. We derive emission measure distributions versus temperature of the entire active region from multifilter XRT data. We ch…
Intrinsic Instability of Coronal Streamers
Feng, S. W.; Chen, Y.; Song, H. Q. +3 more
Plasma blobs are observed to be weak density enhancements as radially stretched structures emerging from the cusps of quiescent coronal streamers. In this paper, it is suggested that the formation of blobs is a consequence of an intrinsic instability of coronal streamers occurring at a very localized region around the cusp. The evolutionary proces…
The C1XS X-ray Spectrometer on Chandrayaan-1
Grande, M.; Foing, B.; Huovelin, J. +27 more
The Chandrayaan-1 X-ray Spectrometer (C1XS) is a compact X-ray spectrometer for the Indian Space Research Organisation (ISRO) Chandrayaan-1 lunar mission. It exploits heritage from the D-CIXS instrument on ESA's SMART-1 mission. As a result of detailed developments to all aspects of the design, its performance as measured in the laboratory greatly…