Search Publications
A Power-Law Distribution of Solar Magnetic Fields Over More Than Five Decades in Flux
Lamb, D. A.; DeForest, C. E.; Hagenaar, H. J. +3 more
Solar flares, coronal mass ejections, and indeed phenomena on all scales observed on the Sun, are inextricably linked with the Sun's magnetic field. The solar surface is covered with magnetic features observed on many spatial scales, which evolve on differing timescales: the largest features, sunspots, follow an 11-year cycle; the smallest seem to…
Variable Partial Covering and A Relativistic Iron Line in NGC 1365
Zezas, A.; Bianchi, S.; Elvis, M. +9 more
We present a complete analysis of the hard X-ray (2-10 keV) properties of the Seyfert galaxy NGC 1365, based on a 60 ks XMM-Newton observation performed in 2004 January. The two main results are as follows. (1) We detect an obscuring cloud with NH ~ 3.5 × 1023 cm-2 crossing the line of sight in ~25 ks. This implies…
Further Constraints on Thermal Quiescent X-Ray Emission from SAX J1808.4-3658
Wijnands, R.; Heinke, C. O.; Jonker, P. G. +2 more
We observed SAX J1808.4-3658 (1808), the first accreting millisecond pulsar, in deep quiescence with XMM-Newton and (near simultaneously) Gemini-South. The X-ray spectrum of 1808 is similar to that observed in quiescence in 2001 and 2006, describable by an absorbed power law with photon index 1.74 ± 0.11 and unabsorbed X-ray luminosity LX
Fan-Spine Topology Formation Through Two-Step Reconnection Driven by Twisted Flux Emergence
Golub, L.; Aulanier, G.; Schmieder, B. +2 more
We address the formation of three-dimensional nullpoint topologies in the solar corona by combining Hinode/X-ray Telescope (XRT) observations of a small dynamic limb event, which occurred beside a non-erupting prominence cavity, with a three-dimensional (3D) zero-β magnetohydrodynamics (MHD) simulation. To this end, we model the boundary-driven "k…
Relationship between wave processes in sunspots and quasi-periodic pulsations in active region flares
Nakariakov, V. M.; Sych, R.; Karlicky, M. +1 more
A phenomenological relationship between oscillations in a sunspot and quasi-periodic pulsations (QPP) in flaring energy releases at an active region (AR) above the sunspot is established. The analysis of the microwave emission recorded by the Nobeyama Radioheliograph at 17 GHz shows a gradual increase in the power of the 3-min oscillation train in…
A New Dynamical Model for the Black Hole Binary LMC X-1
Remillard, Ronald A.; McClintock, Jeffrey E.; Gou, Lijun +10 more
We present a dynamical model of the high mass X-ray binary LMC X-1 based on high-resolution optical spectroscopy and extensive optical and near-infrared photometry. From our new optical data we find an orbital period of P = 3.90917 ± 0.00005 days. We present a refined analysis of the All Sky Monitor data from RXTE and find an X-ray period of P = 3…
Numerical Simulation of an EUV Coronal Wave Based on the 2009 February 13 CME Event Observed by STEREO
Attrill, Gemma D. R.; Manchester, Ward B., IV; Cohen, Ofer +1 more
On 2009 February 13, a coronal wave—CME—dimming event was observed in quadrature by the Solar Terrestrial Relations Observatory (STEREO) spacecraft. We analyze this event using a three-dimensional, global magnetohydrodynamic model for the solar corona. The numerical simulation is driven and constrained by the observations, and indicates where magn…
Composition, Morphology, and Stratigraphy of Noachian Crust around the Isidis basin
Mangold, N.; Bibring, J. -P.; Mustard, J. F. +5 more
Definitive exposures of pristine, ancient crust on Mars are rare, and the finding that much of the ancient Noachian terrain on Mars exhibits evidence of phyllosilicate alteration adds further complexity. We have analyzed high-resolution data from the Mars Reconnaissance Orbiter in the well-exposed Noachian crust surrounding the Isidis basin. We fo…
Dynamical Mass of the Substellar Benchmark Binary HD 130948BC
Dupuy, Trent J.; Ireland, Michael J.; Liu, Michael C.
We present Keck adaptive optics imaging of the L4+L4 binary HD 130948BC along with archival Hubble Space Telescope and Gemini North observations, which together span ≈ 70% of the binary's orbital period. From the relative orbit, we determine a total dynamical mass of 0.109 ± 0.003 M sun (114 ± 3 M Jup). The flux ratio of HD 1…
The second INTEGRAL AGN catalogue
Mas-Hesse, J. M.; Gehrels, N.; Ricci, C. +7 more
Aims: The INTEGRAL mission provides a large data set for studying the hard X-ray properties of AGN and allows testing of the unified scheme for AGN.
Methods: We present analysis of INTEGRAL IBIS/ISGRI, JEM-X, and OMC data for 199 AGN supposedly detected by INTEGRAL above 20 keV.
Results: The data analysed here allow significant spectral ex…