Search Publications
Multi-spacecraft measurement of anisotropic power levels and scaling in solar wind turbulence
Horbury, T. S.; Osman, K. T.
Measurements by the four Cluster spacecraft in the solar wind are used to determine quantitatively the field-aligned anisotropy of magnetohydrodynamic inertial range turbulence power levels and spectral indexes. We find, using time-lagged second order structure functions, that the spectral index is near 2 around the field-parallel direction, which…
The isolated neutron star candidate 2XMM J104608.7-594306
Motch, C.; Treves, A.; Turolla, R. +2 more
Over the last decade, X-ray observations have revealed the existence of several classes of isolated neutron stars (INSs) which are radio-quiet or exhibit radio emission with properties much at variance with those of ordinary radio pulsars. The identification of new sources is crucial in order to understand the relations among the different classes…
Signatures of field-aligned currents in Saturn's nightside magnetosphere
Coates, A. J.; Dougherty, M. K.; Khurana, K. K. +4 more
We report first results of a survey of near-simultaneous and near-conjugate magnetic field perturbations observed over Saturn's northern and southern nightside auroral regions on ∼40 periapsis passes of the Cassini spacecraft during 2008. Structured azimuthal fields that are generally anti-symmetric north and south were observed at auroral latitud…
Operational validation of HAFv2's predictions of interplanetary shock arrivals at Earth: Declining phase of Solar Cycle 23
Dryer, M.; Fry, C. D.; McKenna-Lawlor, S. M. P. +3 more
This is the third in a series of papers showing the performance of the Hakamada-Akasofu-Fry version 2 (HAFv2) model in predicting, in the operational environment, the arrival of interplanetary shocks at Earth. The first and second studies covered the time of the rise and maximum of Solar Cycle 23. This study covers the declining phase, through Dec…
On the differential rotation of CoRoT-2a
Strassmeier, K. G.; Hatzes, A. P.; Küker, M. +1 more
We apply a robust spot model to fit the light curve of CoRoT-2a. The spots are assumed to be long-living and each has its own rotation period. A model with three circular spots reproduces the basic features of the longitude-time spot coverage map. One of the spots exhibits a noticeably lower rotational frequency than the other two. From the rotati…
On the State of Water Ice on Saturn's Moon Titan and Implications to Icy Bodies in the Outer Solar System
Jewitt, David; Kaiser, Ralf I.; Zheng, Weijun
The crystalline state of water ice in the Solar System depends on the temperature history of the ice and the influence of energetic particles to which it has been exposed. We measured the infrared absorption spectra of amorphous and crystalline water ice in the 10-50 K and 10-140 K temperature ranges, respectively, and conducted a systematic exper…
Hot flow anomalies at Saturn's bow shock
Coates, A. J.; Dougherty, M. K.; Thomsen, M. F. +8 more
We present evidence for the occurrence of hot flow anomalies (HFAs) at Saturn's bow shock. A survey of Cassini magnetic field and electron data taken upstream of the dawn flank bow shock is carried out in order to identify Kronian HFAs. Seventeen events are identified that were all associated with energization of the solar wind electrons and satis…
X-ray Observation of Very High Energy Gamma-Ray Source, HESS J1745-303, with Suzaku
Matsumoto, Hironori; Bamba, Aya; Pühlhofer, Gerd +4 more
Suzaku observations of a TeV unidentified source, HESS J1745-303, are presented. A possible excess of neutral iron line emission is discovered, and is likely associated with the main part of HESS J1745-303, named "region A." It may be an X-ray reflection nebula where the X-rays from previous Galactic center (GC) activity are reflected by a molecul…
Mass Segregation in NGC 2298: Limits on the Presence of an Intermediate Mass Black Hole
Stiavelli, Massimo; Hamilton, Douglas P.; van der Marel, Roeland P. +5 more
Theoretical investigations have suggested the presence of intermediate mass black holes (IMBHs, with masses in the 100-10000 M sun range) in the cores of some globular clusters (GCs). In this paper, we present the first application of a new technique to determine the presence or absence of a central IMBH in globular clusters that have r…
A new determination of the orbit and masses of the Be binary system δ Scorpii
Tuthill, P. G.; Davis, J.; Tango, W. J. +5 more
The binary star δ Sco (HD143275) underwent remarkable brightening in the visible in 2000, and continues to be irregularly variable. The system was observed with the Sydney University Stellar Interferometer (SUSI) in 1999, 2000, 2001, 2006 and 2007. The 1999 observations were consistent with predictions based on the previously published orbital ele…