Search Publications
Hubble Space Telescope observations of Comet 9P/Tempel 1 during the Deep Impact encounter
Weaver, Harold A.; Feldman, Paul D.; A'Hearn, Michael F. +4 more
We report on the Hubble Space Telescope program to observe periodic Comet 9P/Tempel 1 in conjunction with NASA's Deep Impact Mission. Our objectives were to study the generation and evolution of the coma resulting from the impact and to obtain wide-band images of the visual outburst generated by the impact. Two observing campaigns utilizing a tota…
Flow burst-induced Kelvin-Helmholtz waves in the terrestrial magnetotail
Zhang, T. L.; Glassmeier, K. -H.; Lucek, E. +7 more
The Kelvin-Helmholtz instability (KHI) on the boundary of a flow channel in the Earth's plasma sheet is investigated using Cluster and Double Star TC1 data. It is shown that when Cluster moves into the flow channel the magnetometer measures strong oscillations of the magnetic field, that increase as the spacecraft move further into the flow channe…
A Low-Mass H2 Component to the AU Microscopii Circumstellar Disk
Redfield, Seth; Roberge, Aki; France, Kevin +2 more
We present a determination of the molecular gas mass in the AU Microscopii circumstellar disk. Direct detection of a gas component to the AU Mic disk has proven elusive, with upper limits derived from ultraviolet absorption line and submillimeter CO emission studies. Fluorescent emission lines of H2, pumped by the O VI λ1032 resonance l…
In-Orbit Focal Adjustment of the AKARI Telescope with Infrared Camera (IRC) Images
Takagi, T.; Wada, T.; Onaka, T. +4 more
AKARI, currently in space, carries onboard a cryogenically cooled light-weight telescope with silicon carbide mirrors. The wavefront error of the AKARI telescope, obtained in laboratory measurements at 9 K, showed that the expected in-orbit imaging performance was diffraction-limited at a wavelength of 6.2 µm, slightly degraded from that exp…
Discovery of a Possible X-Ray Counterpart to HESS J1804-216
Maeda, Yoshitomo; Kokubun, Motohide; Takahashi, Tadayuki +10 more
Suzaku deep observations have discovered two highly significant nonthermal X-ray sources, Suzaku J1804-2142 (Src 1) and Suzaku J1804-2140 (Src 2), positionally coincident with the unidentified TeV γ-ray source, HESS J1804-216. The X-ray sources are not time variable and show no counterpart in other wavebands, except for the TeV source. Src 1 is un…
Structural parameters of Mayall II = G1 in M31
Wu, H.; Wu, J.; Chen, J. +8 more
Mayall II = G1 is one of the most luminous globular clusters (GCs) known in M31. New deep, high-resolution observations with the Advanced Camera for Surveys on the Hubble Space Telescope are used to provide accurate photometric data to the smallest radii yet. In particular, we present the precise variation of ellipticity and position angle, and of…
Oxygen temperature anisotropy and solar wind heating above coronal holes out to 5 R⊙
Antonucci, E.; Telloni, D.; Dodero, M. A.
The purpose of the paper is to measure the degree of temperature anisotropy of the oxygen ions in the outer corona. The ratio of the Doppler dimmed O VI 1037-1032 line intensity as a function of the velocity of the fast solar wind, computed for typical values of coronal density, is consistent with the observed ratio, only when a significant temper…
Integral-Field Spectroscopy of the Post-Red Supergiant IRC +10420: Evidence for an Axisymmetric Wind
Sahu, Kailash C.; Davies, Ben; Oudmaijer, René D.
We present NAOMI/OASIS adaptive-optics-assisted integral-field spectroscopy of the transitional massive hypergiant IRC +10420, an extreme mass-losing star apparently in the process of evolving from a red supergiant toward the Wolf-Rayet phase. To investigate the present-day mass-loss geometry of the star, we study the appearance of the line emissi…
High-mass X-ray binaries and recent star formation history of the Small Magellanic Cloud
Gilfanov, M. R.; Shtykovskiy, P. E.
We study the relation between high-mass X-ray binary (HMXB) population and recent star formation history (SFH) for the Small Magellanic Cloud (SMC). Using archival optical SMC observations, we have approximated the color-magnitude diagrams of the stellar population by model stellar populations and, in this way, reconstructed the spatially resolved…
A Hubble Space Telescope Survey of the Disk Cluster Population of M31. I. WFPC2 Pointings
Hodge, P. W.; Krienke, O. K.
As a follow-up to the automated cluster search carried out by Williams & Hodge, we have examined 39 Hubble Space Telescope Wide Field Planetary Camera 2 (WFPC2) pointings to locate and study a comprehensive collection of disk clusters. The Williams technique was effective in finding young clusters, but not intermediate-age or old clusters. Our…