Search Publications
The Purple Haze of η Carinae: Binary-induced Variability?
Smith, Nathan; Gull, Theodore R.; Collins, Nicholas R. +1 more
Asymmetric variability in ultraviolet images of the Homunculus obtained with the Advanced Camera for Surveys/High Resolution Camera on the Hubble Space Telescope suggests that η Carinae is indeed a binary system. Images obtained before, during, and after the recent ``spectroscopic event'' in 2003.5 show alternating patterns of bright spots and sha…
XMM-Newton Observations of the Galactic Supernova Remnant CTB 109 (G109.1-1.0)
Sasaki, Manami; Smith, Randall K.; Plucinsky, Paul P. +3 more
We present the analysis of the X-ray Multimirror Mission (XMM-Newton) European Photon Imaging Camera (EPIC) data of the Galactic supernova remnant (SNR) CTB 109 (G109.1-1.0). CTB 109 is associated with the anomalous X-ray pulsar (AXP) 1E 2259+586 and has an unusual semicircular morphology in both the X-ray and the radio and an extended X-ray brigh…
Rapid Penumbral Decay following Three X-Class Solar Flares
Liu, C.; Qiu, J.; Wang, H. +3 more
We show strong evidence that penumbral segments decayed rapidly and permanently right after three X-class solar flares. Two of the three events occurred very recently in NOAA Active Region 10486, an X17 flare on 2003 October 28 and an X10 flare on 2003 October 29. The third X2.3 flare was observed in solar active region NOAA AR 9026 on 2000 June 6…
RHESSI Observations of a Simple Large X-Ray Flare on 2003 November 3
Liu, Wei; Liu, Siming; Jiang, Yan Wei +1 more
We present data analysis and interpretation of a simple X-class flare observed with RHESSI on 2003 November 3. In contrast to other X-class flares observed previously, this flare shows a very simple morphology with well-defined looptop (LT) and footpoint (FP) sources. The almost monotonic upward motion of the LT source and increase in separation o…
Solar Cycle 23: An Anomalous Cycle?
de Toma, Giuliana; White, Oran R.; Chapman, Gary A. +3 more
The latest SOHO VIRGO total solar irradiance (TSI) time series is analyzed using new solar variability measures obtained from full-disk solar images made at the San Fernando Observatory and the Mg II 280 nm index. We discuss the importance of solar cycle 23 as a magnetically simpler cycle and a variant from recent cycles. Our results show the cont…
The Mid-Infrared Luminosity Function of Galaxies in the European Large Area Infrared Space Observatory Survey Southern Fields
Pozzi, F.; Franceschini, A.; Serjeant, S. +7 more
We present the first determination of the 15 µm luminosity function of galaxies from the European Large Area ISO Survey (ELAIS) southern fields. We have adopted a new criterion to separate the quiescent, nonevolving and the starburst, evolving populations based on the ratio of mid-infrared to optical luminosity. Strong evolution is suggested…
The Variable Quiescence of Centaurus X-4
Campana, S.; Mereghetti, S.; Stella, L. +2 more
Centaurus X-4 is one of the best-studied low-mass neutron star transients in quiescence. Thanks to XMM-Newton's large throughput, Centaurus X-4 was observed at the highest signal-to-noise ratio ever. This allowed us to discern rapid (>100 s), large (45%+/-7% rms in the 10-4 to 1 Hz range) intensity variability, especially at low ener…
Time Dependence in Relativistic Collisionless Shocks: Theory of the Variable ``Wisps'' in the Crab Nebula
Spitkovsky, Anatoly; Arons, Jonathan
We describe results from time-dependent numerical modeling of the collisionless reverse shock terminating the pulsar wind in the Crab Nebula. We treat the upstream relativistic wind as composed of ions and electron-positron plasma embedded in a toroidal magnetic field, flowing radially outward from the pulsar in a sector around the rotational equa…
The Ultraviolet Extinction Curve of Intraclump Dust in Taurus (TMC-1): Constraints on the 2175 Å Bump Absorber
Gordon, Karl D.; Whittet, D. C. B.; Clayton, Geoffrey C. +1 more
Ultraviolet extinction curves for three early-type stars that sample dust in the Taurus dark cloud in the vicinity of TMC-1 are analyzed to examine the contribution of internal (intraclump) dust to the total line-of-sight extinction. One of our selected targets samples only dust in the ``diffuse-screen'' component of the cloud, where the dust grai…
Helioseismic Mapping of the Magnetic Canopy in the Solar Chromosphere
Finsterle, W.; McIntosh, S. W.; Jefferies, S. M. +2 more
We determine the three-dimensional topography of the magnetic canopy in and around active regions by mapping the propagation behavior of high-frequency acoustic waves in the solar chromosphere.