Search Publications
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…
Coronal Diagnostic Spectrometer Observations of Isothermal and Multithermal Coronal Loops
Mason, H. E.; Del Zanna, G.; Schmelz, J. T. +3 more
A data set obtained on 2003 January 17 with the Coronal Diagnostic Spectrometer (CDS) shows two loops sitting side by side on the solar disk. These loops are oriented along the CDS slit, so all pixels in each loop were observed simultaneously. So, although the instrument has a relatively slow time cadence, changes as a function of time that may oc…
Degree-one convection and the origin of Enceladus' dichotomy
Grott, M.; Hussmann, H.; Sohl, F.
Recently, the Cassini spacecraft has detected ongoing geologic activity near the south pole of Saturn's moon Enceladus. In contrast, the satellite's north-polar region is heavily cratered and appears to have been geologically inactive for a long time. We propose that this hemispheric dichotomy is caused by interior dynamics with degree-one convect…