Search Publications
X-ray spectral evolution of SAX J1747.0-2853 during outburst activity and confirmation of its transient nature
Ubertini, P.; Bazzano, A.; Heise, J. +6 more
SAX J1747.0-2853 is an X-ray transient which exhibited X-ray outbursts yearly between 1998 and 2001, and most probably also in 1976. The outburst of 2000 was the longest and brightest. We have analyzed X-ray data sets that focus on the 2000 outburst and were obtained with BeppoSAX, XMM-Newton and RXTE. The data cover unabsorbed 2-10 keV fluxes bet…
Compressional waves in the Earth's neutral sheet
Balogh, A.; Glassmeier, K.; Klecker, B. +10 more
. Compressional waves in the Earth's current sheet, driven by the high-speed plasma flows connected to substorms, are investigated using the Cluster magnetometer and plasma instrument. During the time that Cluster had its apogee in the magnetotail (July through October 2001), we have studied 5 events in detail. We find compressional waves in the 3…
Deceleration of the rotational velocities of sunspot groups during their evolution
Wöhl, H.; Brajša, R.; Ruždjak, V. +1 more
Using the Greenwich Photoheliographic Results for the years 1874-1976 the daily rotational velocities for 955 recurrent and 13169 non-recurrent sunspot groups from the first day of their appearance and during their evolution have been determined. The rotational velocities were divided in six latitude strips with a width of five degrees and grouped…
Self-Gravitating Eccentric Disk Models for the Double Nucleus of M31
Statler, Thomas S.; Salow, Robert M.
We present new dynamical models of weakly self-gravitating, finite dispersion eccentric stellar disks around central black holes for the double nucleus of M31. The disk is fixed in a frame rotating at constant precession speed and is populated by stars on quasi-periodic orbits whose parents are numerically integrated periodic orbits in the total p…
Spatially Resolved Ultraviolet Spectra of the High-Velocity Nuclear Outflow of NGC 1068
Ferruit, Pierre; Dopita, Michael A.; Cecil, Gerald +1 more
We present ultraviolet emission-line maps of the narrow-line region (NLR) of NGC 1068. The maps span 115-318 nm, the biconical ionization cone, and several posited jet-ISM interactions, and the compact knots whose optical spectra we reported previously resemble kinematically the quasar associated absorption line systems. Across the NLR, we find th…
The potential of INTEGRAL for the detection of high redshift GRBs
Westergaard, N. J.; Lund, N.; Gorosabel, J. +2 more
We discuss INTEGRAL's ability to detect a high redshift population of Gamma-Ray Bursts (GRBs) in comparison to other high-energy missions. Emphasis is placed on the study of the relative capabilities of IBIS on board INTEGRAL with respect to SWIFT and HETE 2 in detecting a high redshift population of GRBs. We conclude that, if the GRB rate is prop…
Nuclear star formation in NGC 6240
Gallagher, J. S.; de Grijs, R.; Pasquali, A.
We have made use of archival HST BVIJH photometry to constrain the nature of the three discrete sources, A1, A2 and B1, identified in the double nucleus of NGC 6240. STARBURST99 models have been fitted to the observed colours, under the assumption, first, that these sources can be treated as star clusters (i.e. single, instantaneous episodes of st…
On the widths of the Mg X lines near 60 nm in the corona
Dwivedi, B. N.; Wilhelm, K.; Teriaca, L.
We examine the line widths of both components of the Mg X 2s 2S1/2-2p 2P1/2,3/2 doublet at 60.98 nm and 62.50 nm in the low corona of the quiet Sun, and find that the Doppler width (i.e. half 1/e width) broadens from Δ λD ≈ 8.2 pm to ≈9.5 pm (with an estimated relative standard uncertainty of …
Dust in 3CR radio galaxies: On the FR 1 - FR 2 difference
Meisenheimer, K.; Siebenmorgen, R.; Klaas, U. +4 more
We compare three 3CR samples of 11 FR 1 galaxies, 17 FR 2 galaxies and 18 lobe-dominated quasars contained in the ISO Data Archive. In contrast to the powerful FR 2 galaxies with edge-brightened lobes, the low radio power FR 1 galaxies in our sample do not exhibit any high MIR or FIR dust luminosity, which is typical for a buried, intrinsically mo…
Time-resolved Ultraviolet Spectroscopy of the SW Sex Star DW UMa: Confirmation of a Hidden White Dwarf and the Ultraviolet Counterpart to Phase 0.5 Absorption Events
Dhillon, V. S.; Szkody, Paula; Hoard, D. W. +5 more
We present time-resolved ultraviolet (UV) spectroscopy of the SW Sex star DW UMa in the high state. We confirm that shortward of 1500 Å, the high-state UV continuum level is lower than the white dwarf (WD) dominated low-state level. We also do not see the WD contact phases in the high-state eclipse light curves. These results confirm our earlier f…