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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…
Dynamical Evidence for Environmental Evolution of Intermediate-Redshift Spiral Galaxies
Smith, Graham P.; Treu, Tommaso; Ellis, Richard S. +2 more
Combining resolved optical spectroscopy with panoramic HST imaging, we study the dynamical properties of spiral galaxies as a function of position across two intermediate-redshift clusters, and we compare the cluster population to field galaxies in the same redshift range. By modeling the observed rotation curves, we derive maximal rotation veloci…
Time-Distance Imaging of Solar Far-Side Active Regions
Zhao, Junwei
It is of great importance to monitor large solar active regions on the far side of the Sun for space weather forecasting, in particular, to predict their appearance before they rotate into our view from the solar east limb. Local helioseismology techniques, including helioseismic holography and time distance, have successfully imaged solar far-sid…
Spectral and Rotational Changes in the Isolated Neutron Star RX J0720.4-3125
Mori, Kaya; Pavlov, George G.; Kaplan, David L. +1 more
RX J0720.4-3125 is an isolated neutron star that, uniquely in its class, has shown changes in its thermal X-ray spectrum. We use new spectra taken with Chandra's Low Energy Transmission Grating Spectrometer, as well as archival observations, to try to understand the timescale and nature of these changes. We construct light curves, which show both …
A Photoionization Model for the Soft X-Ray Spectrum of NGC 4151
Turner, T. J.; Kraemer, S. B.; Armentrout, B. K.
We present an analysis of archival data from multiple XMM-Newton observations of the Seyfert 1 galaxy NGC 4151. Spectral data from the RGS instruments reveal several strong soft X-ray emission lines, chiefly from hydrogen-like and helium-like oxygen, nitrogen, neon, and carbon. Radiative recombination continua (RRC) from oxygen and carbon are also…