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Simultaneous Ultraviolet and X-Ray Observations of the Seyfert Galaxy NGC 4151. II. Physical Conditions in the UV Absorbers
Gull, T. R.; Kriss, G. A.; Turner, T. J. +8 more
We present a detailed analysis, including photoionization modeling, of the intrinsic absorption in the Seyfert 1 galaxy NGC 4151 using ultraviolet (UV) spectra from the Hubble Space Telescope Space Telescope Imaging Spectrograph and the Far Ultraviolet Spectrographic Explorer obtained 2002 May as part of a set of contemporaneous observations that …
Electron oscillations in the induced martian magnetosphere
Coates, A. J.; Kallio, E.; Fedorov, A. +42 more
The Analyzer of Space Plasmas and Energetic Atoms (ASPERA-3) experiment flown on the Mars Express (MEX) spacecraft includes the Electron Spectrometer (ELS) as part of its complement. The ELS instrument measures the differential electron flux spectrum in a 128-level logarithmic energy sweep within a time period of 4 s. The orbital path of MEX trave…
First ENA observations at Mars: ENA emissions from the martian upper atmosphere
Coates, A. J.; Kallio, E.; Fedorov, A. +44 more
The neutral particle detector (NPD) on board Mars Express has observed energetic neutral atoms (ENAs) from a broad region on the dayside of the martian upper atmosphere. We show one such example for which the observation was conducted at an altitude of 570 km, just above the induced magnetosphere boundary (IMB). The time of flight spectra of these…
FUSE Observation of the Narrow-Line Seyfert 1 Galaxy RE 1034+39: Dependence of Broad Emission Line Strengths on the Shape of the Photoionizing Spectrum
Baron, E.; Leighly, Karen M.; Casebeer, Darrin A.
We present an analysis from simultaneous FUSE, ASCA, and EUVE observations, as well as a reanalysis of archival HST spectra, from the extreme narrow-line Seyfert 1 Galaxy RE 1034+39 (KUG 1031+398). RE 1034+39 has an unusually hard spectral energy distribution (SED) that peaks in the soft X-rays. Its emission lines are unusual in that they can all …
Optical Counterparts of Ultraluminous X-Ray Sources Identified from Archival HST WFPC2 Images
van der Marel, Roeland P.; Colbert, Ed; Ptak, Andrew +3 more
We present a systematic analysis of archival HST WFPC2 ``Association'' data sets that correlate with the Chandra positions of a set of 44 ultraluminous X-ray sources (ULXs) of nearby galaxies. The main motivation is to address the nature of ULXs by searching for optical counterparts. Sixteen of the ULXs are found in early-type galaxies (RC3 Hubble…
No signature of clear CO2 ice from the `cryptic' regions in Mars' south seasonal polar cap
Forget, F.; Bibring, Jean-Pierre; Langevin, Yves +5 more
The seasonal polar ice caps of Mars are composed mainly of CO2 ice. A region of low (< 30%) albedo has been observed within the south seasonal cap during early to mid-spring. The low temperature of this `cryptic region' has been attributed to a clear slab of nearly pure CO2 ice, with the low albedo resulting from absorptio…
A high-resolution spectroscopy survey of β Cephei pulsations in bright stars
Uytterhoeven, K.; De Ridder, J.; Aerts, C. +4 more
We present a study of absorption line-profile variations in early-B type near-main-sequence stars without emission lines. We have surveyed a total of 171 bright stars using the Nordic Optical Telescope (NOTSA), William Herschel Telescope (ING) and Coudé Auxiliary Telescope (ESO). Our sample contains 75% of all O9.5-B2.5 III-V non-emission-line sta…
Waves and horizontal structures in Titan's thermosphere
Waite, J. H.; Yelle, R. V.; Müller-Wodarg, I. C. F. +1 more
The Ion Neutral Mass Spectrometer (INMS) on board the Cassini spacecraft carried out in situ measurements of neutral gas composition above 1025 km altitude in Titan's atmosphere during its flybys in October 2004 (TA) and April 2005 (T5). Strong perturbations are present in the N2 and CH4 densities which we interpret as vertic…
A Strong X-Ray Flux Ratio Anomaly in the Quadruply Lensed Quasar PG 1115+080
Schechter, Paul L.; Fong, Wen-fai; Pooley, David +2 more
PG 1115+080 is a quadruply lensed quasar at z=1.72 whose image positions are well fit by simple models of the lens galaxy (at z=0.31). At optical wavelengths, the bright close pair of images exhibits a modest flux ratio anomaly (factors of ~1.2-1.4 over the past 22 yr) with respect to these same models. We show here that as observed in X-rays with…
Dynamical Mass Estimates for Incomplete Orbits: Young Multiple Stars in Taurus and Ophiuchus
Nelan, E.; Prato, L.; Schaefer, G. H. +2 more
We present recent measurements of the orbital motion in the binaries DF Tau and ZZ Tau and in the triples Elias 12, T Tau, and V853 Oph. We observed these systems with the Fine Guidance Sensors on the Hubble Space Telescope and with adaptive optics imaging at the W. M. Keck and Gemini North Observatories. Based on our measurements and those presen…