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Timescales for electron quasi-linear diffusion by parallel and oblique lower-band chorus waves
Artemyev, A. V.; Agapitov, O. V.; Krasnoselskikh, V. V. +2 more
The loss of relativistic electrons from the Earth's radiation belts can be described in terms of the quasi-linear pitch angle diffusion by cyclotron-resonant waves, provided that their frequency spectrum is broad enough. Chorus waves at large wave-normal angles with respect to the magnetic field are often present in CLUSTER and THEMIS measurements…
Evidence of Wave Damping at Low Heights in a Polar Coronal Hole
Hahn, M.; Savin, D. W.; Landi, E.
We have measured the widths of spectral lines from a polar coronal hole using the Extreme Ultraviolet Imaging Spectrometer on board Hinode. Polar coronal holes are regions of open magnetic field and the source of the fast solar wind. We find that the line widths decrease at relatively low heights. Previous observations have attributed such decreas…
High velocity dispersion in a rare grand-design spiral galaxy at redshift z = 2.18
Erb, Dawn K.; Shapley, Alice E.; Steidel, Charles C. +3 more
Although grand-design spiral galaxies are relatively common in the local Universe, only one has been spectroscopically confirmed to lie at redshift z > 2 (HDFX 28; z = 2.011); and it may prove to be a major merger that simply resembles a spiral in projection. The rarity of spirals has been explained as a result of disks being dynamically `hot' …
Titan’s global crater population: A new assessment
Lorenz, R. D.; Neish, C. D.
We report a revised crater population for Titan using Cassini RADAR data through January 2010 (flyby T65), and make a size-dependent correction for the incomplete coverage (∼33%) using a Monte-Carlo model. Qualitatively, Titan’s landscape is more heavily cratered than Earth, but much less than Mars or Ganymede: the area fraction covered by craters…
Models of the global cloud structure on Venus derived from Venus Express observations
Irwin, P. G. J.; Drossart, P.; Piccioni, G. +6 more
Spatially-resolved near-infrared spectra from the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) on Venus Express have been used to derive improved models of the vertical structure and global distribution of cloud properties in the southern hemisphere of Venus. VIRTIS achieved the first systematic, global mapping of Venus at wavelength…
A Young Massive Stellar Population around the Intermediate-mass Black Hole ESO 243-49 HLX-1
Maccarone, T. J.; Knigge, C.; Farrell, S. A. +9 more
We present Hubble Space Telescope and simultaneous Swift X-ray Telescope observations of the strongest candidate intermediate-mass black hole (IMBH) ESO 243-49 HLX-1. Fitting the spectral energy distribution from X-ray to near-infrared wavelengths showed that the broadband spectrum is not consistent with simple and irradiated disk models, but is w…
3D-HST Grism Spectroscopy of a Gravitationally Lensed, Low-metallicity Starburst Galaxy at z = 1.847
Schmidt, Kasper B.; van Dokkum, Pieter G.; Franx, Marijn +17 more
We present Hubble Space Telescope (HST) imaging and spectroscopy of the gravitational lens SL2SJ02176-0513, a cusp arc at z = 1.847. The UV continuum of the lensed galaxy is very blue, which is seemingly at odds with its redder optical colors. The 3D-HST WFC3/G141 near-infrared spectrum of the lens reveals the source of this discrepancy to be extr…
Hubble Space Telescope Observations of an Outer Field in Omega Centauri: A Definitive Helium Abundance
Anderson, J.; Milone, A. P.; Bedin, L. R. +6 more
We revisit the problem of the split main sequence (MS) of the globular cluster ω Centauri, and report the results of two-epoch Hubble Space Telescope observations of an outer field, for which proper motions give us a pure sample of cluster members, and an improved separation of the two branches of the MS. Using a new set of stellar models covering…
Molecular line survey of the high-mass star-forming region NGC 6334I with Herschel/HIFI and the Submillimeter Array
Ceccarelli, C.; Comito, C.; Schilke, P. +7 more
Aims: We aim at deriving the molecular abundances and temperatures of the hot molecular cores in the high-mass star-forming region NGC 6334I and consequently deriving their physical and astrochemical conditions.
Methods: In the framework of the Herschel guaranteed time key program CHESS (Chemical HErschel Surveys of Star forming regions)…
Polar Field Reversal Observations with Hinode
Ishikawa, R.; Tsuneta, S.; Orozco Suárez, D. +3 more
We have been monitoring yearly variation in the Sun's polar magnetic fields with the Solar Optical Telescope aboard Hinode to record their evolution and expected reversal near the solar maximum. All magnetic patches in the magnetic flux maps are automatically identified to obtain the number density and magnetic flux density as a function of the to…