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The dayside reconnection voltage applied to Saturn's magnetosphere
Masters, A.
The ability of magnetic reconnection between interplanetary and planetary magnetic fields to drive a planetary magnetosphere can be quantified as the resulting voltage applied to the system. We present analytical model predictions of the dayside reconnection voltage at Saturn, a planet where solar wind driving has been the subject of debate. Model…
Estimating precipitation on early Mars using a radiative-convective model of the atmosphere and comparison with inferred runoff from geomorphology
Rauer, H.; Jaumann, R.; Tirsch, D. +5 more
We compare estimates of atmospheric precipitation during the Martian Noachian-Hesperian boundary 3.8 Gyr ago as calculated in a radiative-convective column model of the atmosphere with runoff values estimated from a geomorphological analysis of dendritic valley network discharge rates. In the atmospheric model, we assume CO2-H2
Origins of massive field stars in the Galactic Centre: a spectroscopic study
Morris, Mark R.; Wang, Q. Daniel; Dong, Hui +2 more
Outside of the known star clusters in the Galactic Centre, a large number of evolved massive stars have been detected; but their origins remain uncertain. We present a spectroscopic study of eight such stars, based on new Gemini Near-Infrared Spectrograph (GNIRS) and Near-IR Integral Field Spectrograph (NIFS) near-infrared observations. This work …
Enhancement of the 6.4 keV Line in the Inner Galactic Ridge: Proton-induced Fluorescence?
Koyama, K.; Tanaka, T.; Fukui, Y. +7 more
A common idea for the origin of the Galactic diffuse X-ray emission, particularly that of the iron lines from neutral and highly ionized atoms, is a superposition of many cataclysmic variables and coronally active binaries. In this scenario, the flux should symmetrically distribute between the east and west on the plane with respect to Sagittarius…
Modeled Interaction of Comet 67P/Churyumov-Gerasimenko with the Solar Wind Inside 2 AU
Ip, W. -H.; Gombosi, T. I.; Rubin, M. +4 more
Periodic comets move around the Sun on elliptical orbits. As such comet 67P/Churyumov-Gerasimenko (hereafter 67P) spends a portion of time in the inner solar system where it is exposed to increased solar insolation. Therefore given the change in heliocentric distance, in case of 67P from aphelion at 5.68 AU to perihelion at ~1.24 AU, the comet's a…
Relating the inhomogeneous power spectrum to the CMB hemispherical anisotropy
Jain, Pankaj; Rath, Pranati K.; Aluri, Pavan K.
We relate the observed hemispherical anisotropy in the cosmic microwave radiation data to an inhomogeneous power spectrum model. The hemispherical anisotropy can be parametrized in terms of the dipole modulation model. This model leads to correlations between spherical harmonic coefficients corresponding to multipoles, l and l +1 . We extract the …
The Three-dimensional Evolution of Ion-scale Current Sheets: Tearing and Drift-kink Instabilities in the Presence of Proton Temperature Anisotropy
Matteini, L.; Burgess, D.; Gingell, P. W.
We present the first three-dimensional (3D) hybrid simulations of the evolution of ion-scale current sheets, with an investigation of the role of temperature anisotropy and associated kinetic instabilities on the growth of the tearing instability and particle heating. We confirm the ability of the ion cyclotron and firehose instabilities to enhanc…
Photometric properties of Ceres from telescopic observations using Dawn Framing Camera color filters
Nathues, Andreas; Li, Jian-Yang; Reddy, Vishnu +7 more
The dwarf planet Ceres is likely differentiated similar to the terrestrial planets but with a water/ice dominated mantle and an aqueously altered crust. Detailed modeling of Ceres' phase function has never been performed to understand its surface properties. The Dawn spacecraft began orbital science operations at the dwarf planet in April 2015. We…
X-Ray Spectral Residuals in NGC 5408 X-1: Diffuse Emission from Star Formation, or the Signature of a Super-Eddington Wind?
Middleton, Matthew J.; Sutton, Andrew D.; Roberts, Timothy P.
If ultraluminous X-ray sources (ULXs) are powered by accretion onto stellar remnant black holes, then many must be accreting at super-Eddington rates. It is predicted that such high accretion rates should give rise to massive, radiatively driven winds. However, observational evidence of a wind, in the form of absorption or emission features, has r…
Observations of Near-Simultaneous Split-Band Solar Type-II Radio Bursts at Low Frequencies
Ramesh, R.; Kathiravan, C.; Hariharan, K.
We report ground-based radio spectral and polarimeter observations of two successive split-band Type-II bursts that occurred on 20 February 2014 at low frequencies (<100 MHz) in association with a solar coronal mass ejection (CME). The temporal interval between the onset of the two bursts was very small, ≈ one minute. Both of the bursts exhibit…