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Coronal Mass Ejections and Galactic Cosmic-Ray Modulation
Gopalswamy, N.; Yashiro, S.; Lara, A. +3 more
We present a study of the long-term evolution of coronal mass ejections (CMEs) observed by the Large Angle and Spectrometric Coronograph (LASCO) on board SOHO during the ascending, maximum, and part of the descending phases of solar cycle 23 and their relation with the modulation of galactic cosmic-ray (GCR) intensity observed at 1 AU by the Clima…
Atmospheres and Plasma Interactions at Saturn's Largest Inner Icy Satellites
Saur, Joachim; Strobel, Darrell F.
We explore the possible existence of atmospheres on Saturn's icy satellites, Mimas, Enceladus, Tethys, Dione, and Rhea. Only the most massive satellite, Rhea, has the potential to hold a thin oxygen atmosphere/exosphere. The masses of the other satellites are too small to retain gravitationally atmospheres in the presence of large thermal escape r…
Models of Five Absorption-Line Systems along the Line of Sight Toward PG 0117+213
Charlton, Jane C.; Masiero, Joseph R.; Churchill, Christopher W. +2 more
We present our investigation into the physical conditions of the gas in five intervening quasar absorption-line systems along the line of sight toward the quasar PG 0117+213, with redshifts of z=0.57, 0.72, 1.04, 1.32, and 1.34. Photoionization modeling of Hubble Space Telescope, Keck I, and Palomar data, using the code Cloudy, is employed to deri…
A Starfish Preplanetary Nebula: IRAS 19024+0044
Sahai, Raghvendra; Sánchez Contreras, Carmen; Morris, Mark
Using the Hubble Space Telescope, we have imaged the OH/IR star IRAS 19024+0044 (I19024) at 0.6, 0.8, 1.1, and 1.6 µm, as part of our surveys of candidate preplanetary nebulae. The images show a multipolar nebula of size ~3.7"×2.3", with at least six elongated lobes emanating from the center of the nebula. Two of the lobes show limb-brighten…
Diffuse X-Rays from the Arches and Quintuplet Clusters
Melia, Fulvio; Wang, Q. Daniel; Rockefeller, Gabriel +1 more
The origin and initial mass function of young stellar clusters near the Galactic center are still poorly understood. Two of the more prominent ones, the Arches and Quintuplet clusters, may have formed from a shock-induced burst of star formation, given their similar age and proximity to each other. Their unusual mass distribution, however, may be …
The Discovery of More than 2000 White Dwarfs in the Globular Cluster ω Centauri
Prada Moroni, P. G.; Pulone, L.; Stetson, P. B. +9 more
We present deep multiband (F435W, F625W, and F658N) photometric data of the globular cluster ω Cen collected with the Advanced Camera for Surveys on board the Hubble Space Telescope. We identified in the (F435W - F625W, F435W)-plane more than 2000 white dwarf (WD) candidates using three out of nine available pointings. Such a large sample appears …
A Multiwavelength Study of PSR B0628-28: The First Overluminous Rotation-powered Pulsar?
Becker, Werner; Jessner, Axel; Kramer, Michael +2 more
The ROSAT source RX J0630.8-2834 was suggested by positional coincidence to be the X-ray counterpart of the pulsar PSR B0628-28. This association, however, was regarded to be unlikely on the basis of the computed energetics of the putative X-ray counterpart. In this paper we report on multiwavelength observations of PSR B0628-28 made with the ESO …
Discovery of Multiple Coaxial Rings in the Quadrupolar Planetary Nebula NGC 6881
Kwok, Sun; Su, Kate Y. L.
We report the discovery of multiple two-dimensional rings in the quadrupolar planetary nebula NGC 6881. As many as four pairs of rings are seen in the bipolar lobes, and three rings are seen in the central torus. While the rings in the lobes have the same axis as one pair of the bipolar lobes, the inner rings are aligned with the other pair. The t…
Supersolar Metallicity in the NLS1 Galaxy Markarian 1044
Pogge, Richard W.; Nicastro, Fabrizio; Mathur, Smita +3 more
We present measurements of the metallicity of the circumnuclear gas in the narrow-line Seyfert 1 (NLS1) galaxy Markarian 1044 using O VI column density measurements from the Far Ultraviolet Spectroscopic Explorer (FUSE) together with C IV, N V, and H I measurements from the Hubble Space Telescope (HST). From the absorption lines we find that the c…
The Lens Galaxy in PG 1115+080 is an Ellipse
Kochanek, Christopher S.; Falco, Emilio E.; Yoo, Jaiyul +1 more
We use the structure of the Einstein ring image of the quasar host galaxy in the four-image quasar lens PG 1115+080 to determine the angular structure of the gravitational potential of the lens galaxy. We find that it is well described as an ellipsoid and that the best-fit nonellipsoidal models are consistent with the ellipsoidal model. We find up…