Search Publications
The Magnetic Structure of Coronal Loops Observed by TRACE
López Fuentes, M. C.; Klimchuk, J. A.; Démoulin, P.
Previous studies have found that coronal loops have a nearly uniform thickness, which seems to disagree with the characteristic expansion of active region magnetic fields. This is one of the most intriguing enigmas in solar physics. We here report on the first comprehensive one-to-one comparison of observed loops with corresponding magnetic flux t…
Data-driven Magnetohydrodynamic Model for Active Region Evolution
Liu, Yang; Wu, S. T.; Hoeksema, J. Todd +1 more
We present a self-consistent, three-dimensional, magnetohydrodynamics model together with time-dependent boundary conditions based on the projected method of characteristics at the source surface (photosphere) to accommodate the observations. The new physics included in this model are differential rotation, meridional flow, effective diffusion, an…
RHESSI Observation of Chromospheric Evaporation
Liu, Wei; Liu, Siming; Jiang, Yan Wei +1 more
We present analyses of the spatial and spectral evolution of hard X-ray emission observed by RHESSI during the impulsive phase of an M1.7 flare on 2003 November 13. In general, as expected, the loop top (LT) source dominates at low energies, while the footpoint (FP) sources dominate the high-energy emission. At intermediate energies, both the LT a…
Observing the Modification of the Acoustic Cutoff Frequency by Field Inclination Angle
McIntosh, Scott W.; Jefferies, Stuart M.
We use observations of a sunspot from the Transition Region and Coronal Explorer (TRACE) spacecraft to demonstrate observationally the modification of the acoustic cutoff frequency in the lower solar chromosphere by the changing the inclination of the magnetic field as first predicted theoretically by Bel & Leroy.
Interferometric 890 µm Images of High-Redshift Submillimeter Galaxies
Le Floc'h, E.; Yun, M. S.; Scott, D. +12 more
We present high-resolution 890 µm images of two 20 mJy submillimeter galaxies, SMM J123711+622212 and MIPS J142824.0+352619, obtained using the Submillimeter Array (SMA). Using submillimeter interferometric observations with an angular resolution of 2.5", the coordinates of these high-redshift sources are determined with an accuracy of 0.2".…
Converging Motion of Hα Conjugate Kernels: The Signature of Fast Relaxation of a Sheared Magnetic Field
Wang, Haimin; Ji, Haisheng; Huang, Guangli +4 more
In this Letter, we present the results from a high-cadence (~40 ms) Hα blue-wing observation of an M1.1-class solar flare, which occurred in NOAA AR 10687 on 2004 November 1. In collaboration with RHESSI, the observation was made with the Hα Fine Structure Telescope at the GanYu Solar Station of the Purple Mountain Observatory. For this flare, a p…
Dissipation of the Perpendicular Turbulent Cascade in the Solar Wind
Hollweg, Joseph V.; Smith, Charles W.; Vasquez, Bernard J. +1 more
The core solar wind protons are observed to be heated perpendicularly to the magnetic field. This is taken to be a signature of the cyclotron damping of the turbulent fluctuations, which are thought to be responsible for the heating. At the same time, it is commonly accepted that the turbulent cascade produces mostly highly oblique (quasi-two-dime…
On the Rates of Coronal Mass Ejections: Remote Solar and In Situ Observations
Cane, H. V.; Gopalswamy, N.; Richardson, I. G. +2 more
We compare the rates of coronal mass ejections (CMEs) as inferred from remote solar observations and interplanetary CMEs (ICMEs) as inferred from in situ observations at both 1 AU and Ulysses from 1996 through 2004. We also distinguish between those ICMEs that contain a magnetic cloud (MC) and those that do not. While the rates of CMEs and ICMEs t…
Mass along the Line of Sight to the Gravitational Lens B1608+656: Galaxy Groups and Implications for H0
McKean, J. P.; Fassnacht, C. D.; Readhead, A. C. S. +3 more
We report the discovery of four groups of galaxies along the line of sight to the B1608+656 gravitational lens system. One group is at the redshift of the primary lensing galaxy (z=0.631) and appears to have a low mass, with eight spectroscopically confirmed members and an estimated velocity dispersion of 150+/-60 km s-1. The three othe…
The Rate of Type Ia Supernovae at High Redshift
Tonry, John L.; Barris, Brian J.
We derive the rates of Type Ia supernovae (SNe Ia) over a wide range of redshifts using a complete sample from the IfA Deep Survey. This sample of more than 100 SNe Ia is the largest set ever collected from a single survey and therefore uniquely powerful for a detailed supernova rate (SNR) calculation. Measurements of the SNR as a function of cosm…