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Rotation of Jets from Young Stars: New Clues from the Hubble Space Telescope Imaging Spectrograph
Bacciotti, Francesca; Coffey, Deirdre; Eislöffel, Jochen +2 more
We report findings from the first set of data in a current survey to establish conclusively whether jets from young stars rotate. We observed the bipolar jets from the T Tauri stars TH 28 and RW Aur and the blueshifted jet from T Tauri star LkHα 321, using the Hubble Space Telescope Imaging Spectrograph. Forbidden emission lines show distinct and …
Four-point discontinuity observations using Cluster magnetic field data: A statistical survey
Balogh, A.; Neubauer, F. M.; Horbury, T. +1 more
Using magnetic field data from the four Cluster spacecraft between February and May 2001, a detailed statistical analysis of interplanetary discontinuities is accomplished. In order to find the surface normals, we apply three different methods: (1) minimum variance analysis (MVA), (2) cross-product method, and (3) triangulation, the latter being t…
Three-dimensional MHD simulation of a flux rope driven CME
Gombosi, Tamas I.; Sokolov, I. V.; Opher, Merav +5 more
We present a three-dimensional (3-D) numerical ideal magnetohydrodynamics (MHD) model, describing the time-dependent expulsion of plasma and magnetic flux from the solar corona that resembles a coronal mass ejection (CME). We begin by developing a global steady-state model of the corona and solar wind that gives a reasonable description of the sol…
Relative Frequencies of Blue Stragglers in Galactic Globular Clusters: Constraints for the Formation Mechanisms
Djorgovski, S. G.; Rich, R. M.; Recio-Blanco, Alejandra +7 more
We discuss the main properties of the Galactic globular cluster (GC) blue straggler stars (BSSs), as inferred from our new catalog containing nearly 3000 BSSs. The catalog has been extracted from the photometrically homogeneous V versus (B-V) color-magnitude diagrams (CMDs) of 56 GCs, based on Wide Field Planetary Camera 2 images of their central …
Obscured Active Galactic Nuclei and the X-Ray, Optical, and Far-Infrared Number Counts of Active Galactic Nuclei in the GOODS Fields
Brandt, William N.; Van Duyne, Jeffrey; Chary, Ranga-Ram +12 more
The deep X-ray, optical, and far-infrared fields that constitute the Great Observatories Origins Deep Survey (GOODS) are sensitive to obscured active galactic nuclei (AGNs; NH>~1022 cm-2) at the quasar epoch (z~2-3), as well as to unobscured AGNs as distant as z~7. Luminous X-ray emission is a sign of accretion …
The Origins of X-Ray Emission from the Hot Spots of FR II Radio Sources
Hardcastle, M. J.; Birkinshaw, M.; Worrall, D. M. +1 more
We use new and archival Chandra data to investigate the X-ray emission from a large sample of compact hot spots of FR II radio galaxies and quasars from the 3C catalog. We find that only the most luminous hot spots tend to be in good agreement with the predictions of a synchrotron self-Compton model with equipartition magnetic fields. At low hot s…
Magnetic Doppler imaging of 53 Camelopardalis in all four Stokes parameters
Petit, P.; Piskunov, N.; Wade, G. A. +5 more
We present the first investigation of the structure of the stellar surface magnetic field using line profiles in all four Stokes parameters. We extract the information about the magnetic field geometry and abundance distributions of the chemically peculiar star 53 Cam by modelling time-series of high-resolution spectropolarimetric observations wit…
High-resolution imaging of the HeII λ4686 emission line nebula associated with the ultraluminous X-ray source in Holmberg II
Zezas, A.; Kaaret, P.; Ward, M. J.
We present Hubble Space Telescope images of the HeIII region surrounding the bright X-ray source in the dwarf irregular galaxy Holmberg II. Using Chandra, we find a position for the X-ray source of (J2000) with an uncertainty of 0.6 arcsec. We identify a bright, point-like optical counterpart centred in the nebula with the X-ray source. The optica…
The Formation of Dust Lanes: Implications for Galaxy Evolution
Yoachim, Peter; Dalcanton, Julianne J.; Bernstein, Rebecca A.
From a survey of edge-on disks, we find that disk galaxies show a sharp, mass-dependent transition in the structure of their dusty ISM. In more massive, rapidly rotating disks with Vc>120kms-1, we see the well-defined dust lanes traditionally associated with edge-on galaxies. However, in more slowly rotating, lower mass ga…
The Role of Magnetic Reconnection in the Observable Features of Solar Eruptions
Raymond, J. C.; van Ballegooijen, A. A.; Lin, J.
There are two competing classes of models for coronal mass ejections (CMEs): those that assume a preexisting magnetic flux rope and those that can make a flux rope during the eruption by magnetic reconnection. The present work is based on the model with a preexisting flux rope. We investigate the evolution of morphological features of the magnetic…