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Hubble Space Telescope Observations of SGR 0526-66: New Constraints on Accretion and Magnetar Models
Kulkarni, S. R.; van Kerkwijk, M. H.; Kaplan, D. L. +5 more
Soft γ-ray repeaters (SGRs) are among the most enigmatic sources known today. Exhibiting huge X-ray and γ-ray bursts and flares, as well as soft quiescent X-ray emission, their energy source remains a mystery. Just as mysterious are the anomalous X-ray pulsars (AXPs), which share many of the same characteristics. Thanks to recent Chandra X-Ray Obs…
A semi-kinetic model of wave-ion interaction in the solar corona
Marsch, E.; Vocks, C.
A semi-kinetic model of the ions in the solar corona is presented, which includes the effects of wave-particle interactions and Coulomb collisions. At the coronal base a spectrum of Alfvén waves is assumed. The spatiotemporal evolution of the spectrum in a 2-D computational domain is determined, taking the absorption of the waves by the particles …
Cold H2O and CO Ice and Gas toward the Galactic Center
Cernicharo, José; Moneti, Andrea; Pardo, Juan Ramón
We present ice- and gas-phase observations of CO, 13CO and of H2O in the mid- and far-infrared taken with the Infrared Space Observatory (ISO) short- and long-wavelength spectrometers toward two positions in the Galactic center region (Sagittarius A* and GCS 3). These data are complemented with Caltech Submillimeter Observato…
Large Doppler Shifts in X-Ray Plasma: An Explosive Start to Coronal Mass Ejection
Schwenn, R.; Curdt, W.; Innes, D. E. +3 more
We report observations, taken with the Solar Ultraviolet Measurements of Emitted Radiation spectrometer, of spatially resolved high red and blue Doppler shifts (up to 650 km s-1) from X-ray-emitting plasma in the corona above a flare. The high Doppler shifts are seen minutes after a fast, faint optical front is seen racing through the s…
Constraints on the O+5 Anisotropy in the Solar Corona
Ofman, L.; Gary, S. P.; Viñas, A.
Velocity distributions of O+5 ions derived from Ultraviolet Coronagraph Spectrometer (UVCS) observations in coronal holes indicate that the O+5 ions are highly anisotropic (T⊥i/T∥i~30-300 at 3.5 Rsolar). The observations provide empirical values for the electron density and the ion temperature…
The stellar content and distance of UGC 4483
Sarajedini, A.; Dolphin, A. E.; Grebel, E. K. +7 more
We present HST/WFPC2 observations of UGC 4483, an irregular galaxy in the M81/NGC 2403 complex. Stellar photometry was carried out with HSTphot, and is complete to V~=26.0 and I~=24.7. We measure the red giant branch tip at I=23.56+/-0.10, and calculate a distance modulus of µ0=27.53+/-0.12 (corresponding to a distance of 3.2+/-0.…
Statistical Properties of Circumnuclear H II Regions in Nearby Galaxies
Alonso-Herrero, Almudena; Knapen, Johan H.
We analyze the statistical properties of the circumnuclear H II regions of a sample of 52 nearby galaxies (v<1000 km s-1) from archival HST/NICMOS H-band and Paα (1.87 µm) observations at unprecedented spatial resolutions of between 1 and 30 pc. We catalog H II regions from the continuum-subtracted Paα images and find H II regi…
A Search for the Damped Lyα Absorber at z=1.86 toward QSO 1244+3443 with NICMOS
Schneider, Glenn; Rieke, Marcia J.; Kulkarni, Varsha P. +5 more
We have carried out a high-resolution imaging search for the galaxy associated with the damped Lyα absorber (DLA) at z=1.859 toward the zem=2.48 quasar QSO 1244+3443, using the Hubble Space Telescope (HST) and the near-infrared camera and multiobject spectrometer (NICMOS). Images were obtained in the broad filter F160W and the narrow fi…
Analysis of blinkers and EUV brightenings in the quiet Sun observed with CDS
Solanki, S. K.; Brković, A.; Rüedi, I.
Movies of quiet Sun regions at disc centre obtained with the Coronal Diagnostic Spectrometer (CDS) onboard the SOHO spacecraft are used to study the properties of transient brightenings seen in the extreme ultraviolet (EUV), so-called blinkers, at three different temperatures sampled simultaneously in the chromospheric He I 584.3 Å (2 x 104
Distribution of magnetic field components in the solar wind plasma
Matthaeus, W. H.; Smith, C. W.; Padhye, N. S.
We examine the probability distribution functions (PDFs) of fluctuations of magnetic field components using the Ulysses and Omnitape data sets to evaluate departures from Gaussian distributions. Functional fits as well as moment comparisons (kurtoses) are used in drawing conclusions concerning the degree of non-Gaussianity. Short-timescale fluctua…