Search Publications
Properties of high-latitude CME-driven disturbances during Ulysses second northern polar passage
St. Cyr, O. C.; Reisenfeld, D. B.; Forsyth, R. J. +2 more
Ulysses observed five coronal mass ejections (CMEs) and their associated disturbances while the spacecraft was immersed in the polar coronal hole (CH) flow above 70° N in late 2001. Of these CMEs, two were very fast (>850 km s-1) driving strong shocks in the wind ahead, and two others were over-expanding. The two fast CMEs were obser…
Global Parameter and Helioseismic Tests of Solar Variability Models
Guenther, D. B.; Demarque, P.; Basu, S. +3 more
We construct models of the structure and evolution of the Sun which include variable magnetic fields and turbulence. The magnetic effects are (1) magnetic pressure, (2) magnetic energy, and (3) magnetic modulation to turbulence. The effects of turbulence are (1) turbulent pressure, (2) turbulent kinetic energy, and (3) turbulent inhibition of the …
Discovery of narrow X-ray absorption features from the low-mass X-ray binary X 1254-690 with XMM-Newton
Parmar, A. N.; Boirin, L.
We report on two XMM-Newton observations of the low-mass X-ray binary X 1254-690. During an XMM-Newton observation of the low-mass X-ray binary in 2001 January a deep X-ray dip was seen while in a second observation one year later no dips were evident. The 0.5-10 keV EPIC spectra from both non-dipping intervals are very similar being modeled by a …
Flux Rope Acceleration and Enhanced Magnetic Reconnection Rate
Moon, Y. -J.; Choe, G. S.; Cheng, C. Z. +1 more
A physical mechanism of flares has emerged from our 2.5-dimensional resistive MHD simulations of the dynamical evolution of current sheet formation and magnetic reconnection and flux rope acceleration subject to the continuous, slow increase of magnetic shear in the arcade. With anomalous nonuniform resistivity in the current sheet the simulation …
Are stellar coronae optically thin in X-rays?. A systematic investigation of opacity effects
Schmitt, J. H. M. M.; Mewe, R.; Audard, M. +2 more
The relevance of resonant scattering in the solar corona has always been discussed controversially. Ratios of emission lines from identical ions but different oscillator strengths have been used in order to estimate damping of resonance lines due to possible resonant scattering, i.e., absorption by photo-excitation and re-emission out of the line …
Post-Asymptotic Giant Branch Evolution in the Large Magellanic Cloud: A Study of the Central Stars of Planetary Nebulae
Villaver, Eva; Shaw, Richard A.; Stanghellini, Letizia
We present medium- and broadband Hubble Space Telescope (HST) photometry of a sample of 35 central stars (CSs) of planetary nebulae (PNs) in the Large Magellanic Cloud (LMC). The observations were made with the Wide Field Planetary Camera 2 (WFPC2) and Space Telescope Imaging Spectrograph instruments on board the HST. By observing LMC objects, our…
Saturn's wayward shepherds: the peregrinations of Prometheus and Pandora
French, Richard G.; Dones, Luke; Lissauer, Jack J. +1 more
Saturn's narrow F ring is flanked by two nearby small satellites, Prometheus and Pandora, discovered in Voyager images taken in 1980 and 1981 (Synnott et al., 1983, Icarus 53, 156-158). Observations with the Hubble Space Telescope (HST) during the ring plane crossings (RPX) of 1995 led to the unexpected finding that Prometheus was ∼19° behind its …
The far-infrared signature of dust in high-latitude regions
del Burgo, C.; Ábrahám, P.; Laureijs, R. J. +1 more
We present ISOPHOT observations of eight interstellar regions in the 60-200 µm wavelength range. The regions belong to mostly quiescent high-latitude clouds and have optical extinction peaks from AV~1-6 mag. From the 150- and 200-µm emission, we derived colour temperatures for the classical big grain component which show a c…
Three-dimensional photoionization modelling of the planetary nebula NGC 3918
Morisset, C.; Barlow, M. J.; Liu, X. -W. +2 more
The three-dimensional Monte Carlo photoionization code MOCASSIN has been applied to construct a realistic model of the planetary nebula NGC 3918. Three different geometric models were tried, the first being the biconical density distribution already used some years ago by Clegg et al. In this model the nebula is approximated by a biconical structu…
New results on GP Com
Marsh, T. R.; Steeghs, D.; Morales-Rueda, L. +3 more
We present high resolution optical and UV spectra of the 46 min orbital period, helium binary, GP Com. Our data contains simultaneous photometric correction which confirms the flaring behaviour observed in previous optical and UV data. In this system all lines show a triple peaked structure where the outer two peaks are associated with the accreti…