Search Publications
On the cause of Saturn's plasma periodicity
André, N.; Coates, A. J.; Dougherty, M. K. +6 more
Periodic plasma enhancements are examined for all Cassini orbits from December 29, 2005 through September 7, 2006. The events, which have UT durations of 3-4 hours, are centered near SLS3 longitude 10° at radial distances near 15 RS and at larger W longitudes at larger distances, reaching 180°W by 49 RS. Magnetic-field data w…
Deep Advanced Camera for Surveys Imaging in the Globular Cluster NGC 6397: Dynamical Models
Anderson, Jay; Dotter, Aaron; Rich, R. Michael +8 more
We present N-body models to complement deep imaging of the metal-poor core-collapsed cluster NGC 6397 obtained with the Hubble Space Telescope. All simulations include stellar and binary evolution in step with the stellar dynamics and account for the tidal field of the Galaxy. We focus on the results of a simulation that began with 100, 000 object…
Analysis of the Fe X and Fe XIV line width in the solar corona using LASCO-C1 spectral data
Schwenn, R.; Mierla, M.; Teriaca, L. +2 more
Aims:The purpose of this paper is to analyze the variation in the line width with height in the inner corona (region above 1.1 R⊙), by using the spectral data from LASCO-C1 aboard SOHO. We used data acquired at activity minimum (August-October 1996) and during the ascending phase of the solar cycle (March 1998).
Methods: Series of i…
Properties of high-degree oscillation modes of the Sun observed with Hinode/SOT
Kosovichev, A. G.; Mitra-Kraev, U.; Sekii, T.
Aims:With the Solar Optical Telescope on Hinode, we investigate the basic properties of high-degree solar oscillations observed at two levels in the solar atmosphere, in the G-band (formed in the photosphere) and in the Ca II H line (chromospheric emission).
Methods: We analyzed the data by calculating the individual power spectra as well as t…
A Kiloparsec-Scale X-Ray Jet in the BL Lac Source S5 2007+777
Maraschi, L.; Cheung, C. C.; Tavecchio, F. +2 more
X-ray jets in AGNs are commonly observed in FR II and FR I radio galaxies, but rarely in BL Lac objects, most probably due to their orientation close to the line of sight and the ensuing foreshortening effects. Only three BL Lac objects are known so far to contain a kpc-scale X-ray jet. In this paper we present the evidence for the existence of a …
High-resolution spectroscopy of K-shell praseodymium with a high-energy microcalorimeter
Boyce, K. R.; Kilbourne, C. A.; Porter, F. S. +7 more
We present a measurement of the K-shell spectrum of He-like through Be-like praseodymium ions trapped in the Livermore SuperEBIT electron beam ion trap using a bismuth absorber pixel on the XRS/EBIT microcalorimeter. This measurement is the first of its kind where the n=2 to n=1 transitions of the various charge states are spectroscopically resolv…
Obscured and powerful AGN and starburst activities at z ~ 3.5
Berta, S.; Omont, A.; Stalin, C. S. +9 more
Aims: Short phases of coeval powerful starburst and AGN activity during the lifetimes of the most massive galaxies are predicted by various models of galaxy formation and evolution. In spite of their recurrence and high luminosity, such events are rarely observed. Finding such systems, understanding their nature, and constraining their number dens…
Probing a massive radio galaxy with gravitational lensing
Muxlow, T. W. B.; McKean, J. P.; Koopmans, L. V. E. +3 more
The gravitational lens system CLASS B2108+213 has two lensed images separated by 4.56arcsec. Such a wide image separation suggests that the lens is either a massive galaxy or composed of a group of galaxies. To investigate the structure of the lensing potential we have carried out new high-resolution imaging of the two lensed images at 1.7GHz with…
Automated Prediction of CMEs Using Machine Learning of CME - Flare Associations
Ipson, S.; Colak, T.; Qahwaji, R. +1 more
Machine-learning algorithms are applied to explore the relation between significant flares and their associated CMEs. The NGDC flares catalogue and the SOHO/LASCO CME catalogue are processed to associate X and M-class flares with CMEs based on timing information. Automated systems are created to process and associate years of flare and CME data, w…
Intermittent turbulence, noisy fluctuations, and wavy structures in the Venusian magnetosheath and wake
Zhang, T. L.; Baumjohann, W.; Volwerk, M. +3 more
Recent research has shown that distinct physical regions in the Venusian induced magnetosphere are recognizable from the variations of strength of the magnetic field and its wave/fluctuation activity. In this paper the statistical properties of magnetic fluctuations are investigated in the Venusian magnetosheath and wake regions. The main goal is …