Search Publications
Temperature and entropy profiles of nearby cooling flow clusters observed with XMM-Newton
Kaastra, J. S.; Tamura, T.; Piffaretti, R. +1 more
We investigate temperature and entropy profiles of 13 nearby cooling flow clusters observed with the EPIC cameras of XMM-Newton. When normalized and scaled by the virial radius the temperature profiles turn out to be remarkably similar. At large radii the temperature profiles show a clear decline starting from a break radius at ~0.1 rvir
Confirmation of Errors in Hipparcos Parallaxes from Hubble Space Telescope Fine Guidance Sensor Astrometry of the Pleiades
Soderblom, David R.; Benedict, G. Fritz; McArthur, Barbara +4 more
We present absolute trigonometric parallaxes and relative proper motions for three members of the Pleiades, obtained with the Hubble Space Telescope's Fine Guidance Sensor 1r, a white-light interferometer. We estimate spectral types and luminosity classes of the stars comprising the astrometric reference frame from R~2000 spectra, VJHK photometry,…
Evolution and characteristics of global Pc5 ULF waves during a high solar wind speed interval
Balogh, A.; Lavraud, B.; Wild, J. A. +9 more
We present an interval of extremely long-lasting narrow-band Pc5 pulsations during the recovery phase of a large geomagnetic storm. These pulsations occurred continuously for many hours and were observed throughout the magnetosphere and in the dusk-sector ionosphere. The subject of this paper is the favorable radial alignment of the Cluster, Polar…
Global solar Doppler velocity determination with the GOLF/SoHO instrument
Jiménez-Reyes, S. J.; García, R. A.; Pallé, P. L. +10 more
The Global Oscillation at Low Frequencies (GOLF) experiment is a resonant scattering spectrophotometer on board the Solar and Heliospheric Observatory (SoHO) mission, originally designed to measure the disk-integrated solar oscillations of the Sun. This instrument was designed in a relative photometric mode involving both wings of the neutral sodi…
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…