Search Publications

Distribution and orientation of northern-hemisphere gullies on Mars from the evaluation of HRSC and MOC-NA data

Neukum, G.; van Gasselt, S.; Reiss, D. +1 more

Martian gullies show morphologic characteristics that indicate the presence of a flowing liquid during their formation process. However, the current climate in the northern hemisphere of Mars does not allow the existence of substantial amounts of liquid water and, therefore, an assessment of the regional distribution and characteristics of gullies…

Radar-bright channels on Titan

Lorenz, R. D.; Janssen, M. A.; Cassini RADAR Team +3 more

During Cassini's T44 flyby of Titan (May 28, 2008), the Cassini SAR (synthetic aperture radar) revealed sinuous channels in the Southwest of Xanadu. These channels feature very large radar cross-sections, up to 5 dB, whereas the angle of incidence was relatively high, ∼20°. This backscatter is larger than allowed by the coherent backscatter model …

The 2008 October Swift detection of X-ray bursts/outburst from the transient SGR-like AXP 1E1547.0-5408

Campana, S.; Tiengo, A.; de Luca, A. +17 more

We report on the detailed study of the 2008 October outburst from the anomalous X-ray pulsar 1E1547.0-5408 discovered through the Swift/Burst Alert Telescope (BAT) detection of soft gamma-ray repeater like short X-ray bursts on 2008 October 3. The Swift/X-ray Telescope (XRT) started observing the source after less than 100s since the BAT trigger, …

Pitch angle transport of electrons due to cyclotron interactions with the coherent chorus subelements

Lakhina, G. S.; Tsurutani, B. T.; Verkhoglyadova, O. P. +1 more

Chorus is a right-hand, circularly-polarized electromagnetic plane wave. Dayside chorus is a bursty emission composed of rising frequency “elements” with duration of ∼0.1 to 1.0 s. Each element is composed of coherent subelements with durations of ∼1 to 100 ms or more. Due to the coherent nature of the chorus subelements/wave packets, energetic el…

Observations of the relationship between frequency sweep rates of chorus wave packets and plasma density

Gurnett, D. A.; Pickett, J. S.; Demekhov, A. G. +8 more

Chorus emissions are generated by a nonlinear mechanism involving wave-particle interactions with energetic electrons. Discrete chorus wave packets are narrowband tones usually rising (sometimes falling) in frequency. We investigate frequency sweep rates of chorus wave packets measured by the Wideband data (WBD) instrument onboard the Cluster spac…

Suzaku Discovery of a Hard X-Ray Tail in the Persistent Spectra from the Magnetar 1E 1547.0-5408 during its 2009 Activity

Enoto, Teruaki; Yamaoka, Kazutaka; Makishima, Kazuo +8 more

The fastest-rotating magnetar 1E 1547.0-5408 was observed in broad-band X-rays with Suzaku for 33 ks on 2009 January 28-29, 7 d after the onset of its latest bursting activity. After removing burst events, the absorption-uncorrected 2-10 keV flux of the persistent emission was measured with the XIS as 5.7 × 10^-1erg cm^-2s^…

Molecular hydrogen in Titan’s atmosphere: Implications of the measured tropospheric and thermospheric mole fractions

Strobel, Darrell F.

The third most abundant species in Titan's atmosphere is molecular hydrogen with a tropospheric/lower stratospheric mole fraction of 0.001 derived from Voyager and Cassini infrared measurements. The globally averaged thermospheric H mole fraction profile from the Cassini Ion Neutral Mass Spectrometer (INMS) measurements implies a small positive gr…

Formation of nitriles and imines in the atmosphere of Titan: combined crossed-beam and theoretical studies on the reaction dynamics of excited nitrogen atoms N(2D) with ethane

Balucani, Nadia; Leonori, Francesca; Petrucci, Raffaele +4 more

Geology of the Selk crater region on Titan from Cassini VIMS observations

Nicholson, Philip D.; Sotin, Christophe; Barnes, Jason W. +9 more

Observations of Titan obtained by the Cassini Visual and Infrared Mapping Spectrometer (VIMS) have revealed Selk crater, a geologically young, bright-rimmed, impact crater located ∼800 km north-northwest of the Huygens landing site. The crater rim-crest diameter is ∼90 km; its floor diameter is ∼60 km. A central pit/peak, 20-30 km in diameter, is …

O VI Absorbers Tracing Hot Gas Associated with a Pair of Galaxies at z = 0.167

Savage, B. D.; Narayanan, A.; Wakker, B. P. +6 more

High signal-to-noise observations of the QSO PKS 0405-123 (z _em = 0.572) with the Cosmic Origins Spectrograph from 1134 to 1796 Å with a resolution of ~17 km s^-1 are used to study the multi-phase partial Lyman limit system (LLS) at z = 0.16716, which has previously been studied using relatively low signal-to-noise spectra fro…