Search Publications
Proper-Motion Measurements of the Cygnus Egg Nebula
Ueta, Toshiya; Meixner, Margaret; Murakawa, Koji
We present the results of proper-motion measurements of the dust shell structure in the Egg Nebula (AFGL 2688, CRL 2688, V1610 Cyg), based on the archived two-epoch data at 2 µm taken with the Hubble Space Telescope. We measured the amount of motion of local structures in the nebula by determining their relative shifts over an interval of 5.…
Auroral Plasma Acceleration Above Martian Magnetic Anomalies
Coates, A. J.; Kallio, E.; Fedorov, A. +25 more
Aurora is caused by the precipitation of energetic particles into a planetary atmosphere, the light intensity being roughly proportional to the precipitating particle energy flux. From auroral research in the terrestrial magnetosphere it is known that bright auroral displays, discrete aurora, result from an enhanced energy deposition caused by dow…
Observation of energy-dependent ionic charge states in impulsive solar energetic particle events
Klecker, B.; Kistler, L. M.; Kucharek, H. +3 more
We measured the mean ionic charge state of Fe in several 3He-rich and heavy-ion rich energetic particle events during the time period 1998 2000. We combined the ionic charge measurements of CELIAS/STOF onboard SOHO (10 100 keV/nuc) with the measurements of SEPICA onboard ACE (180 550 keV/nuc) to investigate the ionic charge distribution…
Double Nucleus in M83
Díaz, Rubén J.; Mast, Damián; Agüero, M. Paz
M83 is one of the nearest galaxies with enhanced nuclear star formation, and it presents one of the best opportunities to study the kinematics and physical properties of a circumnuclear starburst. Our three-dimensional spectroscopy data in the R band confirm the presence of a secondary nucleus or mass concentration (previously suggested by Thatte …
Swift XRT Follow-up Observations of TeV Sources of the HESS Inner Galaxy Survey
Masetti, N.; Bird, A. J.; Ubertini, P. +6 more
In order to provide a firm identification of the newly discovered Galactic TeV sources, a search for counterparts in a broad band from soft X-ray to soft gamma rays is crucial as data in these wave bands allow us to distinguish between different types of suggested models (for example, leptonic vs. hadronic) and, in turn, to disentangle their natur…
X-ray spectral properties of high-redshift radio-loud quasars beyond redshift 4 - first results*
Fabian, A. C.; Worsley, M. A.; Yuan, W. +1 more
We present the results of X-ray spectroscopic observations with XMM-Newton for four high-redshift radio-loud quasars at z > 4. Among these, three objects, namely GBB1508+5714, PMNJ0324-2918 and PKSB1251-407, do not show soft X-ray spectral flattening; the derived upper limits on assumed intrinsic absorption are (3.3-17.3) × 1021cm
Clues to Active Galactic Nucleus Growth from Optically Variable Objects in the Hubble Ultra Deep Field
Koekemoer, A. M.; Mobasher, B.; Hathi, N. P. +9 more
We present a photometric search for objects with point-source components that are optically variable on timescales of weeks to months in the Hubble Ultra Deep Field (HUDF) to i'AB=28.0 mag. The data are split into four substacks of approximately equal exposure times. Objects exhibiting the signature of optical variability are…
Supergranule Superrotation Identified as a Projection Effect
Hathaway, D. H.; Cuntz, M.; Williams, P. E.
Previous measurements of the rotation rate of the supergranule Doppler velocity pattern revealed surprising characteristics: (1) the pattern rotates faster than the plasma at the surface, and, at each latitude, it rotates faster than the plasma at any level below the surface (superrotation), (2) larger cells rotate more rapidly than smaller cells,…
Europa's FUV auroral tail on Jupiter
Clarke, J. T.; Mauk, B. H.; Gérard, J. -C. +3 more
Ultraviolet images of Jupiter's northern aurora obtained in 2005 confirm the existence of an electromagnetic interaction between Europa and the Jovian ionosphere. The auroral signature shows a two-component structure: a quasi-circular Europa spot, followed by a previously undetected faint tail emission trailing in the direction of corotation flow.…
Hubble Space Telescope NICMOS Polarization Measurements of OMC-1
Schultz, A. S. B.; Colgan, Sean W. J.; Burton, Michael G. +2 more
We present 2 µm polarization measurements of positions in the IRc2 and BN regions of the Orion Molecular Cloud (OMC-1) made with NICMOS Camera 2 (0.2" resolution) on the Hubble Space Telescope. Our results are as follows: BN is ~29% polarized by dichroic absorption and appears to be the illuminating source for most of the nebulosity to its n…