Search Publications
The Evolution of Reconnection along an Arcade of Magnetic Loops
Benz, Arnold O.; Grigis, Paolo C.
RHESSI observations of a solar flare showing continuous motions of double hard X-ray sources interpreted as footpoints of magnetic loops are presented. The temporal evolution shows many distinct emission peaks of duration of some tens of seconds (``elementary flare bursts''). Elementary flare bursts have been interpreted as instabilities or oscill…
The First Giant Flare from SGR 1806-20: Observations Using the Anticoincidence Shield of the Spectrometer on INTEGRAL
Götz, D.; Mereghetti, S.; von Kienlin, A. +4 more
A giant flare from the soft gamma-ray repeater SGR 1806-20 has been discovered with the International Gamma-Ray Astrophysics Laboratory (INTEGRAL) on 2004 December 27 and detected by many other satellites. This tremendous outburst, the first one observed from this source, was a hundred times more powerful than the two giant flares previously obser…
Statistical Distributions of Speeds of Coronal Mass Ejections
Yurchyshyn, V.; Wang, H.; Gopalswamy, N. +2 more
We studied the distribution of plane-of-sky speeds determined for 4315 coronal mass ejections (CMEs) detected by the Large Angle and Spectrometric Coronagraph Experiment on board the Solar and Heliospheric Observatory (SOHO LASCO). We found that the speed distributions for accelerating and decelerating events are nearly identical and to a good app…
Spitzer and Hubble Space Telescope Constraints on the Physical Properties of the z~7 Galaxy Strongly Lensed by A2218
Kneib, J. -P.; Le Floc'h, E.; Dole, H. +10 more
We report the detection of a z~7 galaxy strongly lensed by the massive galaxy cluster A2218 (z=0.175) at 3.6 and 4.5 µm using the Spitzer Space Telescope and at 1.1 µm using the Hubble Space Telescope. The new data indicate a refined photometric redshift in the range of 6.6-6.8 depending on the presence of Lyα emission. The spectral en…
Giant Molecular Clouds in M64
Blitz, L.; Rosolowsky, E.
We investigate the properties of giant molecular clouds (GMCs) in the molecule-rich galaxy M64 (NGC 4826). In M64, the mean surface density of molecular gas is 2N(H2)~1022 cm-2 over a 2 kpc region, equal to the surface densities of individual GMCs in the Milky Way. We observed the J=1-->0 transitions of CO,
Hubble Space Telescope and Ground-based Observations of SN 1993J and SN 1998S: CNO Processing in the Progenitors
Filippenko, Alexei V.; Pun, C. S. J.; Garnavich, Peter +13 more
Ground-based and Hubble Space Telescope observations are presented for SN 1993J and SN 1998S. SN 1998S shows strong, relatively narrow circumstellar emission lines of N III-V and C III-IV, as well as broad lines from the ejecta. Both the broad ultraviolet and optical lines in SN 1998S indicate an expansion velocity of ~7000 km s-1. The …
Narrow Iron Kα Lines in Active Galactic Nuclei: Evolving Populations?
Zhou, Xin-Lin; Wang, Jian-Min
We assemble a sample consisting of 66 active galactic nuclei (AGNs) from the literature and from the XMM-Newton archive in order to investigate the origin of the 6.4 keV narrow iron Kα line (NIKAL). The X-ray Baldwin effect of the NIKAL is confirmed in this sample. We find that the equivalent width (EW) of the NIKAL is more strongly inversely corr…
Magnetic Flux Ropes in the Solar Photosphere: The Vector Magnetic Field under Active Region Filaments
Lites, B. W.
This study is an observational search for evidence of prominence-associated magnetic flux ropes at the photospheric level in plage regions away from sunspots. Although there are a few cases of supposed flux rope geometry in the photosphere of complex sunspot regions (notably ``δ sunspots''), such cases appear to be fairly rare and therefore do not…
Reddening, Absorption, and Decline Rate Corrections for a Complete Sample of Type Ia Supernovae Leading to a Fully Corrected Hubble Diagram to v < 30,000 km s-1
Saha, A.; Tammann, G. A.; Reindl, B. +1 more
Photometric (BVI) and redshift data corrected for streaming motions are compiled for 111 ``Branch-normal,'' four 1991T-like, seven 1991bg-like, and two unusual supernovae of Type Ia (SNe Ia). Color excesses E(B-V)host of normal SNe Ia, due to the absorption of the host galaxy, are derived by three independent methods, giving excellent a…
The Evolution of the Optical and Near-Infrared Galaxy Luminosity Functions and Luminosity Densities to z~2
Dickinson, Mark; Ferguson, Henry C.; Giavalisco, Mauro +4 more
Using Hubble Space Telescope and ground-based U through Ks photometry from the Great Observatories Origins Deep Survey, we measure the evolution of the luminosity function and luminosity density in the rest-frame optical (U, B, and R) to z~2, bridging the poorly explored ``redshift desert'' between z~1 and ~2. We also use deep near-infr…