Search Publications
Missions
Journals
Publication Years
The XMM large scale structure survey: optical vs. X-ray classifications of active galactic nuclei and the unified scheme
Maccagni, D.; Chiappetti, L.; Ebrero, J. +25 more
Aims:Our goal is to characterize AGN populations by comparing their X-ray and optical classifications within the framework of the standard orientation-based unified scheme.
Methods: We present a sample of 99 spectroscopically identified (R ≤ 22 mag) X-ray selected point sources in the XMM-LSS survey which are significantly detected (≥3σ) in th…
Constraining the geometry of the neutron star RX J1856.5-3754
Ho, Wynn C. G.
RX J1856.5-3754 is one of the brightest, nearby isolated neutron stars (NSs), and considerable observational resources have been devoted to its study. In previous work, we found that our latest models of a magnetic, hydrogen atmosphere match well the entire spectrum, from X-rays to optical (with best-fitting NS radius R ~ 14 km, gravitational reds…
The XMM-Newton serendipitous survey. IV. Optical identification of the XMM-Newton medium sensitivity survey (XMS)
Pérez-Fournon, I.; Motch, C.; Bromage, G. E. +54 more
Aims:X-ray sources at intermediate fluxes (a few × 10-14 erg cm-2 s-1) with a sky density of ~100 deg-2 are responsible for a significant fraction of the cosmic X-ray background at various energies below 10 keV. The aim of this paper is to provide an unbiased and quantitative description of the X-ray sou…
An XMM-Newton Observation of the Local Bubble Using a Shadowing Filament in the Southern Galactic Hemisphere
Kuntz, K. D.; Henley, David B.; Shelton, Robin L.
We present an analysis of the X-ray spectrum of the Local Bubble, obtained by simultaneously analyzing spectra from two XMM-Newton pointings on and off an absorbing filament in the southern Galactic hemisphere (b~-45deg). We use the difference in the Galactic column density in these two directions to deduce the contributions of the unab…
Sulfur volcanism on Io
Spencer, John; Yelle, Roger; Jessup, Kandis Lea
In February 2003, March 2003 and January 2004 Pele plume transmission spectra were obtained during Jupiter transit with Hubble's Space Telescope Imaging Spectrograph (STIS), using the 0.1″ wide slit and the G230LB grating. The STIS spectra covered the 2100-3100 Å wavelength regions and extended spatially along Io's limb encompassing the region dir…
Flow Field Evolution of a Decaying Sunspot
Liu, Chang; Denker, Carsten; Wang, Haimin +3 more
We study the evolution of the flows and horizontal proper motions in and around a decaying follower sunspot based on time sequences of two-dimensional spectroscopic observations in the visible and white-light imaging data obtained over 6 days from 2005 June 7 to 12. During this time period the sunspot decayed gradually to a pore. The spectroscopic…
Monte Carlo Simulation of Directivity of Interplanetary Radio Bursts
MacDowall, R. J.; Kaiser, M. L.; Thejappa, G.
We have developed a Monte Carlo simulation code to study the effects of refraction due to spatial variation of the solar wind density and scattering due to random density fluctuations on directivities, time profiles, and sizes and positions of the apparent sources of the interplanetary type II and type III radio bursts excited at the fundamental (…
A Streamer Ejection with Reconnection Close to the Sun
Warren, H. P.; Sheeley, N. R., Jr.; Wang, Y. -M.
We previously described coronal events that expand gradually outward over an interval of 1-2 days and then suddenly tear apart in the coronagraph's 2-6 Rsolar field of view to form an outgoing flux rope and an inward system of collapsing loops. Now, we combine LASCO white-light images of the outer corona with spectrally resolved EIT ima…
Deviations from He I Case B Recombination Theory and Extinction Corrections in the Orion Nebula
Martin, P. G.; Blagrave, K. P. M.; Dufour, R. J. +4 more
We are engaged in a comprehensive program to find reliable elemental abundances in and probe the physical structure of the Orion Nebula, the brightest and best-resolved H II region. In the course of developing a robust extinction correction covering our optical and UV FOS and STIS observations, we examined the decrement within various series of He…
Cosmic-Ray Modulation: An Empirical Relation with Solar and Heliospheric Parameters
Mavromichalaki, H.; Karalidi, T.; Paouris, E.
Long-term variations of galactic cosmic rays were compared with the behavior of various solar activity indices and heliospheric parameters during the current solar cycle. This study continues previous works where the cosmic-ray intensity for the solar cycles 20, 21, and 22 was well simulated from the linear combination of the sunspot number, the n…