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Large-scale structure of Saturn's E-ring
Morfill, Gregor E.; Horányi, Mihály; Juhász, Antal
Geysers on the recently discovered, geologically active south-polar region of the moon Enceladus are now recognized as the dominant source of material in Saturn's E ring. The ring was traditionally thought to span the region between 3 to 8 R S , where R S is the radius of Saturn. However, new in situ dust measurements indi…
Discovery of a Very Highly Extinguished Supernova in a Luminous Infrared Galaxy
Colina, L.; Kankare, E.; Efstathiou, A. +9 more
We report the discovery of a confirmed supernova (SN) and a supernova candidate in near-infrared images from the ALTAIR/NIRI adaptive optics system on the Gemini-North Telescope and NICMOS on the Hubble Space Telescope. The Gemini images were obtained as part of a near-infrared K-band search for highly obscured SNe in the nuclear regions of lumino…
Structure and Evolution of Supergranulation from Local Helioseismology
Hirzberger, Johann; Solanki, Sami K.; Gizon, Laurent +1 more
Supergranulation is visible at the solar surface as a cellular pattern of horizontal outflows. Although it does not show a distinct intensity pattern, it manifests itself indirectly in, for example, the chromospheric network. Previous studies have reported significant differences in the inferred basic parameters of the supergranulation phenomenon.…
The Extragalactic Distance Scale without Cepheids
Sakai, Shoko; Mould, Jeremy
Distances of galaxies in the Hubble Space Telescope Key Project are based on the Cepheid period-luminosity relation. An alternative basis is the tip of the red giant branch. Using archival HST data, we calibrate the infrared Tully-Fisher relation using 14 galaxies with tip of the red giant branch measurements. Compared with the Key Project, a high…
Distribution of the O2 infrared nightglow observed with VIRTIS on board Venus Express
Hueso, R.; Sánchez-Lavega, A.; Erard, S. +5 more
We present characteristics of the statistical horizontal distribution of the O2 infrared nightglow over most of the southern hemisphere observed with the VIRTIS instrument over a period spanning nearly 11 months of low solar activity. We show that the distribution is inhomogeneous with the regions of brightest emission reaching ~3 MegaR…
Solar flare forecasting model supported with artificial neural network techniques
Li, R.; Wang, H. N.; Cui, Y. M. +2 more
Nowadays operational models for solar activity forecasting are still based on the statistical relationship between solar activity and solar magnetic field evolution. In order to set up this relationship, many parameters have been proposed to be the measures. Conventional measures are based on the sunspot group classification which provides limited…
Novae as a Class of Transient X-Ray Sources
Mukai, K.; Della Valle, M.; Orio, M.
Motivated by the recently discovered class of faint (1034-1035 ergs s-1) X-ray transients in the Galactic center region, we investigate the 2-10 keV properties of classical and recurrent novae. Existing data are consistent with the idea that all classical novae are transient X-ray sources with durations of months t…
Magnetic field measurements and wind-line variability of OB-type stars
Rygl, K. L. J.; Neiner, C.; Wiersema, K. +8 more
Context: The first magnetic fields in O- and B-type stars that do not belong to the Bp-star class, have been discovered. The cyclic UV wind-line variability, which has been observed in a significant fraction of early-type stars, is likely to be related to such magnetic fields.
Aims: We attempt to improve our understanding of massive-star magne…
Limits on Hot Galactic Halo Gas from X-Ray Absorption Lines
Yao, Y.; Nowak, M. A.; Wang, Q. D. +2 more
Although the existence of large-scale hot gaseous halos around massive disk galaxies has been theorized for a long time, there is yet very little observational evidence. We report the Chandra and XMM-Newton grating spectral detection of O VII and Ne IX Kα absorption lines along the sight line of 4U 1957+11. The line absorption is consistent with t…
Plasma environment of Mars as observed by simultaneous MEX-ASPERA-3 and MEX-MARSIS observations
Barabash, S.; Lundin, R.; Winningham, J. D. +11 more
Simultaneous in situ measurements carried out by the Analyzer of Space Plasma and Energetic Atoms (ASPERA-3) and Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) instruments on board the Mars Express (MEX) spacecraft for the first time provide us with the local parameters of cold ionospheric and hot solar wind plasma components…