Search Publications
Are All Coronal Mass Ejections Hollow Flux Ropes?
Krall, J.
A quantitative specification of a three-dimensional flux rope is examined statistically for comparison to previously published statistical measures of coronal mass ejections (CMEs) as observed by the Solar Maximum Mission (SMM) spacecraft. The three-dimensional geometry that has been previously shown to reproduce statistical measures (average angu…
The Posteruptive Evolution of a Coronal Dimming
McIntosh, Scott W.; Davey, Alisdair R.; Leamon, Robert J. +1 more
We discuss the posteruptive evolution of a ``coronal dimming'' based on observations of the EUV corona from the Solar and Heliospheric Observatory and the Transition Region and Coronal Explorer (TRACE). This discussion highlights the roles played by magnetoconvection-driven magnetic reconnection and the global magnetic environment of the plasma in…
Seismic Study of the Chemical Composition of the Solar Convection Zone
Basu, Sarbani; Antia, H. M.; Lin, Chia-Hsien
Recent downward revision of solar heavy-element abundances using a three-dimensional atmospheric model has introduced serious discrepancies between standard solar models and helioseismic inferences about solar structure. In this paper we investigate the possibility of determining the heavy-element abundances using helioseismic inversion techniques…
Contamination by Surface Effects of Time-Distance Helioseismic Inversions for Sound Speed beneath Sunspots
Rajaguru, S. P.; Couvidat, S.
Using Doppler velocity data from the SOI/MDI instrument on board the SOHO spacecraft, we do time-distance helioseismic inversions for sound-speed perturbations beneath 16 sunspots observed in high-resolution mode. We clearly detect ringlike regions of enhanced sound speed beneath most sunspot penumbrae, extending from near the surface to depths of…
Direct Measurement of the Radius and Density of the Transiting Exoplanet HD 189733b with the CHARA Array
Swain, Mark; van Belle, Gerard T.; McAlister, Harold A. +5 more
We have measured the angular diameter of the transiting extrasolar planet host star HD 189733 using the CHARA optical/IR interferometric array. Combining our new angular diameter of 0.377+/-0.024 mas with the Hipparcos parallax leads to a linear radius for the host star of 0.779+/-0.052 Rsolar and a radius for the planet of 1.19+/-0.08 …
Validation of Helioseismology through Forward Modeling: Realization Noise Subtraction and Kernels
Hanasoge, S. M.; Duvall, T. L., Jr.; Couvidat, S.
Through a series of numerical simulations of the near-surface acoustic wavefield of the Sun, we show the utility of the forward approach in local helioseismology. We demonstrate and apply a method to subtract a large fraction of the realization noise from the simulated data. The ability to attain high signal-to-noise ratios from brief forward calc…
Halo Coronal Mass Ejections and Configuration of the Ambient Magnetic Fields
Liu, Y.
In this study, we seek a correlation between the speed of active region-related halo coronal mass ejections (CMEs) and the configuration of the ambient magnetic fields. Having studied 99 halo CMEs in the period from 2000 to 2004, we find that CMEs under the heliospheric current sheet are significantly slower than CMEs situated under unidirectional…
A Changing Solar Shape
Bush, R. I.; Emilio, M.; Kuhn, J. +1 more
The Sun's shape is sensitive to the influence of gravity, rotation, and local turbulence and magnetic fields in its outer atmosphere. A careful measurement of this shape has long been sought to better understand the solar structure and its change during the 11 yr solar cycle. Numerous disparate measurements of the solar oblateness or the fractiona…
A Photometrically Detected Forming Cluster of Galaxies at Redshift 1.6 in the GOODS Field
Fiore, F.; Castellano, M.; Pentericci, L. +9 more
We report the discovery of a localized overdensity at z~1.6 in the GOODS-South field, presumably a poor cluster in the process of formation. The three-dimensional galaxy density has been estimated on the basis of well-calibrated photometric redshifts from the multiband photometric GOODS-MUSIC catalog using the (2+1)-dimensional technique. The dens…
Hubble Space Telescope and Optical Observations of Three Pulsating Accreting White Dwarfs in Cataclysmic Variables
Szkody, Paula; Sion, Edward M.; Solheim, Jan-Erik +8 more
Ultraviolet observations using the Solar Blind Channel on the Hubble Space Telescope provide light curves and low-resolution spectra of three pulsating white dwarfs in the cataclysmic variables SDSS J013132.39-090122.3, SDSS J161033.64-010223.3, and SDSS J220553.98+115553.7. The UV light curves show enhanced pulsation amplitudes over those from si…