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…
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…
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…
Correlations between Supermassive Black Holes, Velocity Dispersions, and Mass Deficits in Elliptical Galaxies with Cores
Kormendy, John; Bender, Ralf
High-dynamic-range surface photometry in a companion paper makes possible accurate measurement of the stellar light deficits L def and mass deficits M def associated with the cores of elliptical galaxies. We show that L def correlates with velocity dispersions σ of the host galaxy bulge averaged outside the central…
A Determination of the Spin of the Black Hole Primary in LMC X-1
Steiner, James F.; Remillard, Ronald A.; McClintock, Jeffrey E. +7 more
The first extragalactic X-ray binary, LMC X-1, was discovered in 1969. In the 1980s, its compact primary was established as the fourth dynamical black hole candidate. Recently, we published accurate values for the mass of the black hole and the orbital inclination angle of the binary system. Building on these results, we have analyzed 53 X-ray spe…
Abundant Circumstellar Silica Dust and SiO Gas Created by a Giant Hypervelocity Collision in the ~12 Myr HD172555 System
Bryden, G.; Wyatt, M. C.; Chen, C. H. +4 more
The fine dust detected by infrared (IR) emission around the nearby β Pic analog star HD172555 is very peculiar. The dust mineralogy is composed primarily of highly refractory, nonequilibrium materials, with approximately three quarters of the Si atoms in silica (SiO2) species. Tektite and obsidian lab thermal emission spectra (nonequili…