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The radio-ultraviolet spectral energy distribution of the jet in 3C 273
Meisenheimer, K.; Jester, S.; Röser, H. -J. +1 more
We present deep VLA and HST observations of the large-scale jet in 3C 273 matched to 0.3 arcsec resolution. The observed spectra show a significant flattening in the infrared-ultraviolet wavelength range. The jet's emission cannot therefore be assumed to arise from a single electron population and requires the presence of an additional emission co…
Stars in the Hubble Ultra Deep Field
Panagia, N.; Walsh, J. R.; Koekemoer, A. M. +11 more
We identified 46 unresolved source candidates in the Hubble Ultra Deep Field (HUDF) down to i775=29.5. Unresolved objects were identified using a parameter S, which measures the deviation from the curve of growth of a point source. Extensive testing of this parameter was carried out, including the effects of decreasing signal-to-noise r…
VLT narrow-band photometry in the Lyman continuum of two galaxies at z ∼3. Limits to the escape of ionizing flux
Buat, V.; Burgarella, D.; Inoue, A. K. +2 more
We have performed narrow-band imaging observations with the Very Large Telescope, aimed at detecting the Lyman continuum (LC) flux escaping from galaxies at z∼3. We do not find any significant LC flux from our sample of two galaxies in the Hubble Deep Field South, at z=3.170 and 3.275. The corresponding lower limits on the F1400/F9…
Resolving the Inner Cavity of the HD 100546 Disk: A Candidate Young Planetary System?
Heap, S. R.; Grady, C. A.; Woodgate, B. +4 more
The inner 100 AU of HD 100546 is studied via far-ultraviolet long-slit spectroscopy with the Hubble Space Telescope Space Telescope Imaging Spectrograph (STIS). The star is surrounded by reflection nebulosity, which can be traced 100 AU in the continuum, and by emission from H I Lyα, N I, Si II, and fluorescent H2 transitions. The Lyα e…
INTEGRAL observations of SS433: Results of a coordinated campaign
Bikmaev, I. F.; Sunyaev, R. A.; Sakhibullin, N. A. +18 more
Results of simultaneous INTEGRAL and optical observations of the galactic microquasar SS433 in May 2003 and INTEGRAL /RXTE observations in March 2004 are presented. Persistent precessional variability with a maximum to minimum uneclipsed hard X-ray flux ratio of ∼ 4 is discovered. The 18 60 keV X-ray eclipse is found to be in phase with optical an…
Measurement of the Energy Release Rate and the Reconnection Rate in Solar Flares
Shibata, Kazunari; Isobe, Hiroaki; Takasaki, Hiroyuki
By using the method presented by Isobe et al., the nondimensional reconnection rate vin/vA has been determined for the impulsive phase of three two-ribbon flares, where vin is the velocity of the reconnection inflow and vA is the Alfvén velocity. The nondimensional reconnection rate is important to make …
The Chandra view of extended X-ray emission from Pictor A
Hardcastle, M. J.; Croston, J. H.
We discuss the extended X-ray emission seen in three archival Chandra observations, and one archival XMM-Newton observation, of the Fanaroff-Riley type II radio galaxy, Pictor A. The overall properties of the X-ray lobes are consistent with the conclusions of earlier works that the extended X-ray emission is largely due to the inverse-Compton proc…
The Link between Star Formation and Accretion in LINERs: A Comparison with Other Active Galactic Nucleus Subclasses
O'Halloran, B.; Dudik, R. P.; Satyapal, S. +1 more
We present archival high-resolution X-ray imaging observations of 25 nearby LINERs observed by ACIS on board Chandra. This sample builds on our previously published proprietary and archival X-ray observations and includes the complete set of LINERs with published black hole masses and FIR luminosities that have been observed by Chandra. Of the 82 …
Equatorial electron density measurements in Saturn's inner magnetosphere
Gurnett, D. A.; Persoon, A. M.; Dougherty, M. K. +4 more
Upper hybrid resonance emissions detected by the Radio and Plasma Wave Science (RPWS) instrument on the Cassini spacecraft are used to obtain electron densities on five equatorial orbits of Saturn at radial distances ranging from 3 to 9 saturnian radii (RS). The electron density profiles for these orbits show a highly repeatable radial …
Halos of Spiral Galaxies. I. The Tip of the Red Giant Branch as a Distance Indicator
Ferguson, H. C.; Rich, R. M.; Mouhcine, M. +2 more
We have imaged the halo populations of a sample of nearby spiral galaxies using the Wide Field Planetary Camera 2 on board the Hubble Space Telescope with the aim of studying the stellar population properties and relating them to those of the host galaxies. In four galaxies, the red giant branch is sufficiently well populated to measure the magnit…