Search Publications
X-Ray Properties of the Quasar HE 0450-2958
Zhou, Xin-Lin; Wang, Jian-Min; Yang, Fang +1 more
We present an XMM-Newton EPIC observation of HE 0450-2958, which may be a ``naked'' quasar as suggested by Magain and coworkers. The XMM-Newton EPIC spectra show a substantial soft X-ray excess and a steep photon index, as well as marginal evidence for a weak Fe Kα line. The X-ray absorption is consistent with the Galactic level. The 0.3-10 keV EP…
Molecular and Atomic Excitation Stratification in the Outflow of the Planetary Nebula M27
France, Kevin; Feldman, Paul D.; Andersson, B. -G. +5 more
High-resolution spectroscopy with FUSE and HST STIS of atomic and molecular velocity stratification in the nebular outflow of M27 challenge models of the abundance kinematics in planetary nebulae. The simple picture of a very high speed (~1000 km s-1), high-ionization, radiation-driven stellar wind surrounded by a slower (~10 km s-…
The X-Ray Binary Population in M33. II. X-Ray Spectra and Variability
Zezas, A.; Fabbiano, G.; Kim, D. -W. +2 more
In this paper we investigate the X-ray spectra and X-ray spectral variability of compact X-ray sources for 3 Chandra observations of the Local Group galaxy M33. The observations are centered on the nucleus and the star-forming region NGC 604. In the observations, 261 sources have been detected. For a total of 43 sources the number of net counts is…
Mass and interior of Enceladus from Cassini data analysis
Iess, Luciano; Anabtawi, Aseel; Tortora, Paolo +4 more
Gravity results are available from radio Doppler data acquired by the Deep Space Network during the encounter of the Cassini spacecraft with Enceladus in February 2005. We report the mass of Enceladus to be (1.0798±0.0016)×10 kg, which implies a density of 1608.9±4 kgm. For a core made of hydrated silicates with a density of 2500 kg m -3
Scanning an Interplanetary Magnetic Cloud Using High-Energy Protons
Riihonen, E.; Torsti, J.; Kocharov, L. +2 more
We applied a numerical modeling of the solar energetic particle (SEP) event inside a magnetic cloud in the solar wind to analyze the 17-22 MeV proton flux anisotropy observed on 1998 May 2 with the Energetic and Relativistic Nuclei and Electron (ERNE) instrument on the Solar and Heliospheric Observatory (SOHO), when SOHO was inside a magnetic clou…
Spatial variability, composition and thickness of the seasonal north polar cap of Mars in mid-spring
Hansen, G.; Grassi, D.; Formisano, V. +4 more
The planetary fourier spectrometer (PFS) for the Mars express mission (MEX) is an infrared spectrometer operating in the wavelength range from 1.2 to 45 µm by means of two spectral channels, called SWC (short wavelength channel) and LWC (long wavelength channel), covering, respectively, 1.2-5.5 and 5.5-45 µm. The middle-spring Martian …
Decametric N Burst: A Consequence of the Interaction of Two Coronal Mass Ejections
Mandrini, C. H.; van Driel-Gesztelyi, L.; Culhane, J. L. +5 more
Radio emissions of electron beams in the solar corona and interplanetary space are tracers of the underlying magnetic configuration and of its evolution. We analyse radio observations from the Culgoora and WIND/WAVES spectrographs, in combination with SOHO/LASCO and SOHO/MDI data, to understand the origin of a type N burst originating from NOAA AR…
Unbinned maximum-likelihood estimators for low-count data. Applications to faint X-ray spectra in the Taurus molecular cloud
Audard, M.; Güdel, M.; Franciosini, E. +5 more
Traditional binned statistics such as χ2 suffer from information loss and arbitrariness of the binning procedure, which is especially important at low count rates as encountered in the XMM-Newton Extended Survey of the Taurus Molecular Cloud (XEST). We point out that the underlying statistical quantity (the log likelihood L) does not re…
Further observations of Hipparcos red stars and standards for UBV(RI)C photometry
Kilkenny, D.; Marang, F.; Koen, C. +2 more
We present homogeneous and standardized UBV(RI)C JHK photometry for over 100 M stars selected from an earlier paper on the basis of apparent photometric constancy. L photometry has been obtained for stars brighter than about L = 6. Most of the stars have a substantial number of UBV(RI)C observations and, it is hoped, will pro…
On the Effects of Dissipative Turbulence on the Narrow Emission-Line Ratios in Seyfert Galaxies
Kraemer, S. B.; Crenshaw, D. M.; Bottorff, M. C.
We present a photoionization model study of the effects of microturbulence and dissipative heating on emission lines for number and column densities, elemental abundances, and ionizations typical for the narrow emission line regions (NLRs) of Seyfert galaxies. Earlier studies of NLR spectra generally found good agreement between the observations a…