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Is the Bursting Radio Source GCRT J1745-3009 a Double Neutron Star Binary?
Treves, A.; Possenti, A.; Turolla, R.
GCRT J1745-3009 is a peculiar transient radio source in the direction of the Galactic center. It was observed to emit a series of ~1 Jy bursts at 0.33 GHz, with a typical duration of ~10 minutes and at apparently regular intervals of ~77 minutes. If the source is indeed at the distance of the Galactic center, as seems likely, we show that its obse…
Energetic particle fluxes in the exterior cusp and the high-latitude dayside magnetosphere: statistical results from the Cluster/RAPID instrument
Asikainen, T.; Mursula, K.
In this paper we study the fluxes of energetic protons (30 4000 keV) and electrons (20 400 keV) in the exterior cusp and in the adjacent high-latitude dayside plasma sheet (HLPS) with the Cluster/RAPID instrument. Using two sample orbits we demonstrate that the Cluster observations at high latitudes can be dramatically different because the satell…
Flare X-Ray Observations of AB Doradus: Evidence of Stellar Coronal Opacity
Mathioudakis, M.; Keenan, F. P.; Matranga, M. +1 more
X-ray spectra of the late-type star AB Dor obtained with the XMM-Newton satellite are analyzed. AB Dor was particularly active during the observations. An emission measure reconstruction technique is employed to analyze flare and quiescent spectra, with emphasis on the Fe XVII 15-17 Å wavelength region. The Fe XVII 16.78 Å/15.01 Å line ratio incre…
A nightside source of Saturn's kilometric radiation: Evidence for an inner magnetosphere energy driver
Gurnett, D. A.; Kurth, W. S.; Cecconi, B. +5 more
During Cassini's orbit insertion about Saturn, the spacecraft passed within 1.4 Rs of the planet passing from dayside into the nightside region. During this nightside passage, the onboard Radio and Plasma Wave (RPWS) instrument surprisingly detected Saturn kilometric radiation (SKR). Prior to this encounter, it was believed that SKR ori…
Large-scale activity in solar eruptive events of October November 2003 observed from SOHO/EIT data
Grechnev, V. V.; Chertok, I. M.
Large-scale solar disturbances associated with powerful flares and coronal mass ejections (CMEs) during two passages of a grand system of three active regions in October November 2003 are analyzed using data obtained with the SOHO/EIT EUV telescope. Dimmings (transient coronal holes) and, to a lesser extent, coronal waves (traveling emitting front…
Stagnation Flow in Thin Streamer Boundaries
Nerney, Steven; Suess, Steven T.
Slow solar wind is believed to arise in the legs or near the cusp of streamers, inside the brightness boundary. In an earlier study, we used an analytic model of flow in this layer to analyze the effect of the magnetic field on the geometry of the flow. That study successfully described those conditions that can lead to a decrease of the flow spee…
Chandra Observations of Coronal Emission from the Early G Supergiants α and β Aquarii
Ayres, Thomas R.; Harper, Graham M.; Brown, Alexander
We report Chandra detections of coronal X-rays from the early G supergiants α Aquarii (HD 209750: G2 Ib) and β Aquarii (HD 204867: G0 Ib). Previous ROSAT observations of these archetypical ``hybrid chromosphere'' stars were inconclusive, in the case of α Aqr owing to a 38' mispointing, and for β Aqr because of a small positional discrepancy of the…
Modeling the solar energetic particle events in closed structures of interplanetary magnetic field
Torsti, J.; Kocharov, L.; Huttunen-Heikinmaa, K. +1 more
We undertook a numerical modeling of the solar energetic particle (SEP) event inside a loop-like magnetic cloud in the solar wind. Particles accelerated near the Sun are injected into the cloud of a previous coronal mass ejection (CME) that already has expanded through 1 AU. In the framework of focused transport, we perform Monte Carlo simulations…
Near-IR imaging of Asteroid 4 Vesta
de Pater, I.; Gibbard, S.; Marchis, F. +2 more
The Keck Observatory's adaptive optics (AO) system has been used to observe Asteroid 4 Vesta during its 2003 closest approach to Earth. Broadband K- and L-band images, centered at 2.1 and 3.6 µm, respectively, are presented here. The sharpness of the images was improved by applying a deconvolution algorithm, MISTRAL, to the images. The K- an…
Dust Extinction in Compact Planetary Nebulae
Kwok, S.; Lee, T. -H.
The effects of dust extinction on the departure from axisymmetry in the morphology of planetary nebulae (PNs) are investigated through a comparison of the radio free-free emission and hydrogen recombination line images. The dust extinction maps from five compact PNs are derived using high-resolution (~0.1") Hα and radio maps of the HST and VLA. Th…