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Saturn's Rings at True Opposition
French, Richard G.; Dones, Luke; Salo, Heikki +2 more
On 2005 January 14, the Saturn system was observed at true opposition with the planetary camera of the Wide Field Planetary Camera 2 (WFPC2) on the Hubble Space Telescope. This was the culmination of nearly a decade of similar UBVRI observations, yielding a uniform set of over 400 high spatial resolution and photometrically accurate radial profile…
On the nature of optical nuclei in FR I radio-galaxies from ACS/HST imaging polarimetry
Capetti, A.; Sparks, W. B.; Chiaberge, M. +4 more
We obtained optical imaging polarimetry with the ACS/HRC aboard the HST of the 9 closest radio-galaxies in the 3C catalogue with an FR I morphology. The nuclear sources seen in direct HST images in these galaxies are found to be highly polarized with levels in the range ~2-11% with a median value of 7%. We discuss the different mechanisms that pro…
Can Chandra Resolve the Remaining Cosmic X-Ray Background?
Hickox, Ryan C.; Markevitch, Maxim
The deepest extragalactic X-ray observation, the 2 Ms Chandra Deep Field North (CDF-N), resolves ~80% of the total extragalactic cosmic X-ray background (CXB) in the 1-2 keV band. Recent work has shown that 70% of the remaining CXB flux is associated with sources detected by the Hubble Space Telescope (HST). This paper uses the existing CDF-N data…
Are plasma depletions in Saturn's ionosphere a signature of time-dependent water input?
Moore, Luke; Mendillo, Michael
Recent radio occultation measurements by the Cassini spacecraft reveal the presence of numerous ``ionospheric holes'', or plasma depletions, in Saturn's upper atmosphere that cannot be explained with standard photochemical theory. The holes are remarkably similar in size and shape to artificially-created depletions first observed in the terrestria…
Plasma Outflows in Coronal Streamers
Noci, Giancarlo; Gavryuseva, Elena
In this Letter we show that it is possible to determine slow velocities (~20 km s-1) in the extended solar corona by means of the ratio of the resonance doublet of O VI. We apply this technique to a quiescent streamer at solar minimum, observed by the Ultraviolet Coronagraph Spectrometer (UVCS) for 4 consecutive days, and determine the …
MeV right-handed neutrinos and dark matter
Nezri, E.; Frère, J. -M.; Ling, F. -S. +3 more
We consider the possibility of having an MeV right-handed neutrino as a dark matter constituent. The initial reason for this study was the 511 keV spectral line observed by the satellite experiment INTEGRAL: could it be due to an interaction between dark matter and baryons? Independently of this, we find a number of constraints on the assumed righ…
A high-resolution ultraviolet absorption spectrum of supernova ejecta in SN1006
Blair, William P.; Fesen, Robert A.; Hamilton, Andrew J. S.
We report a high-resolution, far-ultraviolet, Space Telescope Imaging Spectrograph (STIS) E140M spectrum of the strong, broad SiII, III and IV features produced by the ejecta of the supernova of 1006 AD (SN1006) seen in absorption against the background Schweizer-Middleditch OB subdwarf star. The spectrum confirms the extreme sharpness of the red …
XMM-Newton and INTEGRAL observations of the black hole candidate XTE J1817-330
Haberl, F.; Greiner, J.; Sala, G. +2 more
Aims:The galactic black hole candidate
An in-depth study of the pre-polar candidate WX Leonis Minoris
Gänsicke, B. T.; Schwope, A. D.; Vogel, J.
Optical photometry, spectroscopy, and XMM-Newton ultraviolet and X-ray observations with full phase coverage are used for an in-depth study of WX LMi, a system formerly termed a low-accretion rate polar. We find a constant low-mass accretion rate, dot{M} ∼ 1.5 × 10-13 M_⊙ yr-1, a peculiar accretion geometry with one spot not …
Wavelength Determination for Solar Features Observed by the EUV Imaging Spectrometer on Hinode
Doschek, George A.; Hara, Hirohisa; Culhane, Len +10 more
A wavelength calibration of solar lines observed by the high resolution EUV Imaging Spectrometer (EIS) on the Hinode satellite is reported. Spectral features of the quiet sun and of two mildly active areas were measured and calibrated. A listing of the stronger observed lines with identification of the leading contributor ions is presented. 41 lin…