Search Publications
Magnetic Reconnection Flux and Coronal Mass Ejection Velocity
Qiu, Jiong; Yurchyshyn, Vasyl B.
We explore the relationship between the total reconnection flux ψrec estimated from flare observations and the velocity VCME of coronal mass ejections (CMEs) observed with the Large Angle and Spectrometric Coronagraph (LASCO) Experiment. Our study includes 13 events with varying magnetic configurations in source regions. It i…
Stellar Disk Truncations at High z: Probing Inside-Out Galaxy Formation
Trujillo, Ignacio; Pohlen, Michael
We have conducted a systematic search for stellar disk truncations in disklike galaxies at intermediate redshift (z<1.1) using the Hubble Ultra Deep Field data. We use the position of the truncation as a direct estimator of the size of the stellar disk. After accounting for the surface brightness evolution of the galaxies, our results suggest t…
Evidence of Primordial Clustering around the QSO SDSS J1030+0524 at z=6.28
Panagia, N.; Djorgovski, S. G.; Stern, D. +7 more
We present tentative evidence of primordial clustering, manifested as an excess of color-selected objects in the field of the QSO SDSS J1030+0524 at redshift z=6.28. We have selected objects red in i775-z850 on the basis of Hubble Space Telescope Advanced Camera for Surveys imaging of a field centered on the QSO. Compared to …
Statistics of Active Region Complexity: A Large-Scale Fractal Dimension Survey
Gallagher, Peter T.; McAteer, R. T. James; Ireland, Jack
A quantification of the magnetic complexity of active regions using a fractal dimension measure is presented. This fully automated approach uses full-disk MDI magnetograms of active regions from a large data set (2742 days of the SOHO mission, 9342 active region images) to compare the calculated fractal dimension of each region to both its Mount W…
An XMM-Newton View of the Soft Gamma Repeater SGR 1806-20: Long-Term Variability in the Pre-Giant Flare Epoch
Tiengo, A.; Götz, D.; Mereghetti, S. +7 more
The low-energy (<10 keV) X-ray emission of the soft gamma repeater SGR 1806-20 has been studied by means of four XMM-Newton observations carried out in the last two years, the latest performed in response to a strong sequence of hard X-ray bursts observed on 2004 October 5. The source was caught in different states of activity; over the 2003-20…
Constraints on z~10 Galaxies from the Deepest Hubble Space Telescope NICMOS Fields
Bouwens, R. J.; Illingworth, G. D.; Thompson, R. I. +1 more
We use all available fields with deep NICMOS imaging to search for J110-dropouts (H160,AB<~28) at z~10. Our primary data set for this search is the two J110+H160 NICMOS fields taken in parallel with the Advanced Camera for Surveys (ACS) Hubble Ultra Deep Field (UDF). The 5 σ limiting magnitudes were ~…
A Detailed Study of Molecular Clouds toward the TeV Gamma-Ray Supernova Remnant G347.3-0.5
Yamaoka, K.; Fukui, Y.; Onishi, T. +4 more
The supernova remnant G347.3-0.5 (J1713.7-3946) is known as one of the unique SNRs that emit TeV γ-rays, as well as nonthermal X-rays. We present a detailed study of molecular gas toward this SNR obtained with the 4 m millimeter and submillimeter telescope NANTEN at an angular resolution of 2.6 arcmin. This study has revealed that several intensit…
On the Origins of Solar EIT Waves
Thompson, B. J.; Laurenza, M.; Cliver, E. W. +1 more
Approximately half of the large-scale coronal waves identified in images obtained by the Extreme-Ultraviolet Imaging Telescope (EIT) on the Solar and Heliospheric Observatory from 1997 March to 1998 June were associated with small solar flares with soft X-ray intensities below C class. The probability of a given flare of this intensity having an a…
The Ionized Gas and Nuclear Environment in NGC 3783. V. Variability and Modeling of the Intrinsic Ultraviolet Absorption
Kaiser, Mary Elizabeth; Brandt, W. N.; Kaspi, Shai +13 more
We present results on the location, physical conditions, and geometry of the outflow in the Seyfert 1 galaxy NGC 3783 from a study of the variable intrinsic UV absorption. Based on analysis of 18 observations with the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope and six observations with the Far Ultraviolet Spectroscopi…
The Stellar Populations of the M31 Halo Substructure
Lewis, Geraint F.; Ibata, Rodrigo A.; Johnston, Kathryn V. +5 more
We present the first results from our survey of stellar substructure in the outskirts of M31 using the Advanced Camera for Surveys on board the Hubble Space Telescope. We discuss the stellar populations associated with five prominent stellar overdensities discovered during the course of our panoramic ground-based imaging survey with the Isaac Newt…