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Measuring the Spin of GRS 1915+105 with Relativistic Disk Reflection

Fabian, A. C.; Miller, J. M.; Homan, J. +5 more

GRS 1915+105 harbors one of the most massive known stellar black holes in the Galaxy. In 2007 May, we observed GRS 1915+105 for ~117 ks in the low/hard state using Suzaku. We collected and analyzed the data with the Hard X-ray Detector/Positive Intrinsic Negative and X-ray Spectrometer cameras spanning the energy range from 2.3 to 55 keV. Fits to …

Global hybrid simulations: Foreshock waves and cavitons under radial interplanetary magnetic field geometry

Russell, C. T.; Omidi, N.; Blanco-Cano, X.

We use global hybrid (kinetic ions and fluid electrons) simulations to study the solar wind interaction with the magnetosphere for a radial ($\theta$ _vB = 0) interplanetary magnetic field (IMF) geometry. Global hybrid simulations provide a collective picture of processes taking place in the foreshock, bow shock, and magnetosheath. Becau…

Variation of different components of Jupiter's auroral emission

Nichols, J. D.; Clarke, J. T.; Grodent, D. +2 more

The Hubble Space Telescope (HST) data set obtained over two campaigns in 2007 is used to determine the long-term variability of the different components of Jupiter's auroras. Three regions on the planet's disc are defined: the main oval, the low-latitude auroras, and the high-latitude auroras. The UV auroral power emitted from these regions is ext…

Unique chronostratigraphic marker in depositional fan stratigraphy on Mars: Evidence for ca. 1.25 Ma gully activity and surficial meltwater origin

Head, J. W.; Fassett, C. I.; Schon, S. C.

Long-term optical and X-ray variability of the Seyfert galaxy Markarian 79

Gaskell, C. M.; Breedt, E.; Horne, K. +8 more

We present the results of concurrent X-ray and optical monitoring of the Seyfert 1 galaxy Mrk 79 over a period of more than 5yr. We find that on short to medium time-scales (days to a few tens of days) the 2-10 keV X-ray and optical u- and V-band fluxes are significantly correlated, with a delay between the bands consistent with 0d. We show that m…

Modelling and observations of photospheric magnetic helicity

Démoulin, P.; Pariat, E.

Mounting observational evidence of the emergence of twisted magnetic flux tubes through the photosphere have now been published. Such flux tubes, formed by the solar dynamo and transported through the convection zone, eventually reach the solar atmosphere. Their accumulation in the solar corona leads to flares and coronal mass ejections. Since rec…

Comparison of transient horizontal magnetic fields in a plage region and in the quiet Sun

Ishikawa, R.; Tsuneta, S.

Aims: The properties of transient horizontal magnetic fields (THMFs) in both plage and quiet Sun regions are obtained and compared.
Methods: Spectro-polarimetric observations with the Solar Optical Telescope (SOT) on the Hinode satellite were carried out with a cadence of about 30 s for both plage and quiet regions located near the disk center…

Multiple origins of linear dunes on Earth and Titan

Rubin, David M.; Hesp, Patrick A.

Dunes with relatively long and parallel crests are classified as linear dunes. On Earth, they form in at least two environmental settings: where winds of bimodal direction blow across loose sand, and also where single-direction winds blow over sediment that is locally stabilized, be it through vegetation, sediment cohesion or topographic shelter f…

Electron and proton heating by solar wind turbulence

Cranmer, S. R.; Matthaeus, W. H.; Kasper, J. C. +2 more

Previous formulations of heating and transport associated with strong magnetohydrodynamic (MHD) turbulence are generalized to incorporate separate internal energy equations for electrons and protons. Electron heat conduction is included. Energy is supplied by turbulent heating that affects both electrons and protons and is exchanged between them v…

The Presence of Two Distinct Red Giant Branches in the Globular Cluster NGC 1851

Joo, Seok-Joo; Han, Sang-Il; Kim, Hak-Sub +4 more

There is a growing body of evidence for the presence of multiple stellar populations in some globular clusters, including NGC 1851. For most of these peculiar globular clusters, however, the evidence for the multiple red giant branches (RGBs) having different heavy elemental abundances as observed in ω Centauri is hitherto lacking, although spread…