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The Evolution of Titan's Mid-Latitude Clouds
Sotin, C.; Langevin, Y.; Bellucci, G. +24 more
Spectra from Cassini's Visual and Infrared Mapping Spectrometer reveal that the horizontal structure, height, and optical depth of Titan's clouds are highly dynamic. Vigorous cloud centers are seen to rise from the middle to the upper troposphere within 30 minutes and dissipate within the next hour. Their development indicates that Titan's clouds …
Metallicities, Relative Ages, and Kinematics of Stellar Populations in ω Centauri
Pasquini, L.; Pancino, E.; Bellazzini, M. +3 more
We present results of an extensive spectroscopic survey of subgiant stars in the stellar system ω Cen. Using infrared Ca II triplet lines, we derived metallicities and radial velocities for more than 250 stars belonging to different stellar populations of the system. We find that the most metal-rich component, the anomalous subgiant branch (SGB-a)…
Weak Compressible Magnetohydrodynamic Turbulence in the Solar Corona
Chandran, Benjamin D. G.
This Letter presents a calculation of the power spectra of weakly turbulent Alfvén waves and fast magnetosonic waves (“fast waves”) in low-β plasmas. It is shown that three-wave interactions transfer energy to high-frequency fast waves and, to a lesser extent, high-frequency Alfvén waves. High-frequency waves produced by MHD turbulence are a promi…
Near-infrared properties of i-drop galaxies in the Hubble Ultra Deep Field
Bunker, Andrew J.; McMahon, Richard G.; Stanway, Elizabeth R.
We analyse near-infrared Hubble Space Telescope (HST)/Near-Infrared Camera and Multi-Object Spectrometer F110W (J) and F160W (H) band photometry of a sample of 27 i'-drop candidate z~= 6 galaxies in the central region of the HST/Advanced Camera for Surveys Ultra Deep Field. The infrared colours of the 20 objects not affected by near neighbours are…
High-altitude cusp flow dependence on IMF orientation: A 3-year Cluster statistical study
Fedorov, A.; Budnik, E.; Grigoriev, A. +7 more
We report on the statistical properties of the plasma flows measured by the Cluster spacecraft in the high-altitude cusp region of the Northern Hemisphere as a function of the interplanetary magnetic field (IMF) orientation, with selected clock angle intervals. The technique uses a magnetic field model, taking into account the actual solar wind co…
Rapid Change of δ Spot Structure Associated with Seven Major Flares
Liu, Yu; Liu, Chang; Denker, Carsten +4 more
A large fraction of major flares occur in active regions that exhibit a δ configuration. The formation and disintegration of δ configurations is very important in understanding the evolution of photospheric magnetic fields. In this paper we study the relationship between the change in δ spot structures and associated major flares. We present a new…
What Is the Neon Abundance of the Sun?
Basu, Sarbani; Bahcall, John N.; Serenelli, Aldo M.
We have evolved a series of 13 complete solar models that utilize different assumed heavy-element compositions. Models that are based upon the heavy-element abundances recently determined by Asplund and coworkers are inconsistent with helioseismological measurements. However, models in which the neon abundance is increased by 0.4-0.5 dex to logN(N…
Quasi-parallel Shock Structure and Processes
Balogh, A.; Thomsen, M. F.; Lembège, B. +11 more
Observational Evidence of the Kink Instability in Solar Filament Eruptions and Sigmoids
Rust, D. M.; LaBonte, B. J.
Two lines of observational evidence are used to infer that the MHD helical kink instability is associated with solar eruptions. The senses of twist and writhe are determined in images of seven erupting filaments obtained at 10830, 1600, 195, and 171 Å. In every case the sense of twist is the same as the sense of writhe, as required for a kink. Fro…
Probing the Environment in Gamma-Ray Bursts: The Case of an X-Ray Precursor, Afterglow Late Onset, and Wind Versus Constant Density Profile in GRB 011121 and GRB 011211
Piro, L.; Frontera, F.; Costa, E. +9 more
In this paper we present BeppoSAX and XMM-Newton observations of two long gamma-ray bursts (GRBs), the X-ray-rich event of 2001 December 11 (GRB 011211) and the hard and very bright event of 2001 November 21 (GRB 011121). In both events we find evidence of a late X-ray burst taking place several minutes after the prompt emission. In the November b…