Search Publications
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…
Dust Activity in Comet 67P/Churyumov–Gerasimenko from February 20 to April 20, 2003
Lara, L. M.; Gutiérrez, P. J.; Licandro, J. +1 more
Broadband imaging of Comet 67P/Churyumov–Gerasimenko has provided more data on the characterisation of the target of the ESA Rosetta Mission. The comet monitoring between rh=2.37 and rh=2.78 AU postperihelion shows a prominent dust coma which extends up to ≈ 25,000 km from the nucleus, and a long dust structure in approximate…
Origin and Acceleration of the Slow Solar Wind
Habbal, Shadia Rifai; Woo, Richard
This Letter uses Doppler dimming measurements by SOHO UVCS to elucidate the origin and acceleration of the slow solar wind. By investigating plasma flow in the corona over an active region during 2000 May 14-16, we confirm what has been suggested by the presence of the imprint of active regions in the solar wind near Earth orbit, that active regio…
Ionospheric signatures of plasma injections in the cusp triggered by solar wind pressure pulses
Cerisier, Jean-Claude; Marchaudon, AuréLie; Bosqued, Jean-Michel +7 more
We describe coordinated observations made on 14 July 2001 simultaneously in the midaltitude cusp by Cluster and at the cusp's ionospheric magnetic footprint by Super Dual Auroral Radar Network (SuperDARN) and Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) during a period of three successive solar wind dynamic pressure pulses. In asso…
High-Altitude CUSP: The Extremely Dynamic Region in Geospace
Chen, Jiasheng; Fritz, Theodore A.
The high-altitude dayside cusps (both northern and southern) are extremely dynamic regions in geospace. Large diamagnetic cavities with significant fluctuations of the local magnetic field strength have been observed there. These cusp diamagnetic cavities are always there day after day and are as large as 6 RE Associated with these cavi…
The star formation history of the LSB galaxy UGC 5889
Bomans, D. J.; Vallenari, A.; Schmidtobreick, L.
We present HST photometry of the LSB galaxy UGC 889 and derive its recent star formation history. In the last 200 Myr the star formation proceeded in modest bursts at a rate of the order of 10-2-10-3 M⊙/yr, with periods of extremely low SFR or even quiescence. The rate derived from the present study for the last 20…
XMM spectroscopy of the transient supersoft source RXJ0513.9 - 6951: probing the dynamic white dwarf photosphere
Charles, P. A.; Heathcote, B.; McGowan, K. E. +3 more
The highly luminous (>1037ergs-1) supersoft X-ray sources (SSSs) are believed to be Eddington-limited accreting white dwarfs undergoing surface hydrogen burning. The current paradigm for SSSs involves thermally unstable mass transfer from a 1-2Msolar companion. However, this model has never been directly confirm…