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Hubble Space Telescope Space Telescope Imaging Spectrograph Spectroscopy of the Environment in the Starburst Core of M82
O'Connell, R. W.; Smith, L. J.; Gallagher, J. S., III +3 more
We present optical HST STIS observations made with two slits crossing four of the optically brightest starburst clumps near the nucleus of M82. These provide Hα kinematics, extinction, electron density, and emission measures. From the radial velocity curves derived from both slits we confirm the presence of a stellar bar. We derive a new model for…
Mass of Saturn's magnetodisc: Cassini observations
André, N.; Coates, A. J.; Russell, C. T. +5 more
Saturn's ring current was observed by Pioneer 11 and the two Voyager spacecraft to extend 8-16 R S in the equatorial plane and appeared to be driven by stress balance with the centrifugal force. We present Cassini observations that show thin current sheets on the dawn flank of Saturn's magnetosphere, symptomatic of the formation of a …
Dynamics of the Narrow-Line Region in the Seyfert 2 Galaxy NGC 1068
Kraemer, S. B.; Crenshaw, D. M.; Das, V.
We present dynamical models based on a study of high-resolution long-slit spectra of the narrow-line region (NLR) in NGC 1068 obtained with the Space Telescope Imaging Spectrograph (STIS) aboard the Hubble Space Telescope (HST). The dynamical models consider the radiative force due to the active galactic nucleus (AGN), gravitational forces from th…
Nonlinear force-free models for the solar corona. I. Two active regions with very different structure
Régnier, S.; Priest, E. R.
Context: With the development of new instrumentation providing measurements of solar photospheric vector magnetic fields, we need to develop our understanding of the effects of current density on coronal magnetic field configurations.
Aims: The object is to understand the diverse and complex nature of coronal magnetic fields in active regions …
Evidence that Synchrotron Emission from Nonthermal Electrons Produces the Increasing Submillimeter Spectral Component in Solar Flares
Costa, J. E. R.; Silva, Adriana V. R.; Kaufmann, P. +4 more
We investigate the origin of the increasing spectra observed at submillimeter wavelengths detected in the flare on 2 November 2003 starting at 17:17 UT. This flare, classified as an X8.3 and 2B event, was simultaneously detected by RHESSI and the Solar Submillimeter Telescope (SST) at 212 and 405 GHz. Comparison of the time profiles at various wav…
Chandra and Hubble Space Telescope Observations of Gamma-Ray Blazars: Comparing Jet Emission at Small and Large Scales
Maraschi, L.; Wolter, A.; Cheung, C. C. +3 more
We present new Chandra and HST data for four gamma-ray blazars selected on the basis of radio morphology with the aim of revealing X-ray and optical emission from their jets at large scales. All the sources have been detected. Spectral energy distributions (SEDs) of the large-scale jets are obtained as well as new X-ray spectra for the blazar core…
GRO J1655-40: Early Stages of the 2005 Outburst
Smith, D. A.; Shrader, C. R.; Rupen, M. +4 more
The black hole X-ray binary transient GRO J1655-40 underwent an outburst beginning in early 2005. We present the results of our multiwavelength observational campaign to study the early outburst spectral and temporal evolution, which combines data from X-ray (RXTE and INTEGRAL), radio (VLA), and optical (ROTSE and SMARTS) instruments. During the r…
Orientations of LASCO Halo CMEs and their connection to the flux rope structure of interplanetary CMEs
Yurchyshyn, V.; Lynch, B. J.; Lepping, R. P. +2 more
Coronal mass ejections (CMEs) observed near the Sun via LASCO coronographic imaging are the most important solar drivers of geomagnetic storms. ICMEs, their interplanetary, near-Earth counterparts, can be detected in situ, for example, by the Wind and ACE spacecraft. An ICME usually exhibits a complex structure that very often includes a magnetic …
Progressive Star Formation in the Young SMC Cluster NGC 602
Tosi, M.; Sabbi, E.; Nota, A. +9 more
NGC 602 is a young stellar cluster located in a peripheral region of the Small Magellanic Cloud (SMC) known as the wing. Far from the main body of the galaxy and abutting the Magellanic Bridge, the SMC's wing is characterized by low gas and stellar content. With deep optical imaging from the Advanced Camera for Surveys (ACS) aboard the Hubble Spac…
21 cm Synthesis Observations of VIRGOHI 21-A Possible Dark Galaxy in the Virgo Cluster
Impey, Chris; van Driel, Wim; Davies, Jonathan +10 more
Many observations indicate that dark matter dominates the extragalactic universe, yet no totally dark structure of galactic proportions has ever been convincingly identified. Previously, we have suggested that VIRGOHI 21, a 21 cm source we found in the Virgo Cluster using Jodrell Bank, was a possible dark galaxy because of its broad line width (~2…