Search Publications
Accelerated magnetosheath flows caused by IMF draping: Dependence on latitude
Farrugia, C. J.; Erkaev, N. V.; Torbert, R. B. +2 more
In previous work we used a semi-analytical treatment to describe accelerated magnetosheath flows caused by the draping of interplanetary magnetic field (IMF) lines around the magnetosphere. Here, we use the same approach, i.e., modeling the magnetic field lines as elastic strings, to examine how the magnetic tension force, one of the two agents re…
Upper limits on the high-energy emission from gamma-ray bursts observed by AGILE-GRID
Antonelli, L. A.; Costa, E.; Mereghetti, S. +60 more
Context. The detection and the characterization of the highenergy emission component from individual gamma-ray bursts (GRBs) is one of the key science objectives of the currently operating gamma-ray satellite AGILE, launched in April 2007. In its first two years of operation AGILE detected three GRBs with photons of energy larger than 30 MeV. One …
Testing three derivative methods of stellar population synthesis models
Han, Zhanwen; Zhang, Yu; Liu, Jinzhong +2 more
The number of methods used to study the properties of galaxies is increasing, and it is very important to test these methods. Galactic globular clusters (GCs) provide an excellent medium for such tests, because they can be considered as simple stellar populations. We present ages and metallicities for 40 Galactic GCs as determined from three publi…
On the cooling trend of SGR 0526-66
Göǧüş, Ersin; Güver, Tolga; Özel, Feryal
We present a systematic analysis of all archival Chandra observations of the soft gamma repeater SGR 0526-66. Our results show that the X-ray flux of SGR 0526-66 decayed by about 20 per cent between 2000 and 2009. We employ physically motivated X-ray spectral models and determine the effective temperature and the strength of the magnetic field at …
Horizontal flow fields observed in Hinode G-band images. III. The decay of a satellite sunspot and the role of magnetic flux removal in flaring
Verma, M.; Denker, C.
Context. Emergence of magnetic flux plays an important role in the initiation of flares. However, the role of submerging magnetic flux in prompting flares is more ambiguous, not the least because of the scarcity of observations.
Aims: The flare-prolific active region NOAA 10930 offered both a developing δ-spot and a decaying satellite sunspot…
A Suzaku Study of Ejecta Structure and Origin of Hard X-Ray Emission in the Supernova Remnant G 156.2+5.7
Katsuda, Satoru; Petre, Robert; Yamaguchi, Hiroya +3 more
We report on an X-ray study of the evolved Galactic supernova remnant (SNR) G 156.2
Convective Bursts and the Coupling of Saturn's Equatorial Storms and Interior Rotation
Heimpel, Moritz; Aurnou, Jonathan M.
Temporal variations of Saturn's equatorial jet and magnetic field hint at rich dynamics coupling the atmosphere and the deep interior. However, it has been assumed that rotation of the interior dynamo must be steady over tens of years of modern observations. Here we use a numerical convection model and scaling estimates to show how equatorial conv…
Magnetopause energy transfer dependence on the interplanetary magnetic field and the Earth's magnetic dipole axis orientation
Fear, R. C.; Palmroth, M.; Honkonen, I.
We examine the spatial variation of magnetospheric energy transfer using a global magnetohydrodynamic (MHD) simulation (GUMICS-4) and a large data set of flux transfer events (FTEs) observed by the Cluster spacecraft. Our main purpose is to investigate whether it is possible to validate previous results on the spatial energy transfer variation fro…
The distribution of metals in hot DA white dwarfs
Barstow, M. A.; Hubeny, I.; Dickinson, N. J.
The importance to stellar evolution of understanding the metal abundances in hot white dwarfs is well known. Previous work has found the hot DA white dwarfs REJ 1032+532, REJ 1614-085 and GD 659 to have highly abundant, stratified photospheric nitrogen, due to the narrow absorption-line profiles of the far-ultraviolet (FUV) N V doublet and the lac…
On the unmixing of MEx/OMEGA hyperspectral data
Schmidt, Frédéric; Daglis, Ioannis A.; Themelis, Konstantinos E. +3 more
This paper presents a comparative study of three different types of estimators used for supervised linear unmixing of two MEx/OMEGA hyperspectral cubes. The algorithms take into account the constraints of the abundance fractions, in order to get physically interpretable results. Abundance maps show that the Bayesian maximum a posteriori probabilit…