Search Publications
Structure and clumping in the fast wind of NGC6543
Prinja, R. K.; Fullerton, A. W.; Massa, D. L. +2 more
Far-ultraviolet spectroscopy from the FUSE satellite is analysed to uniquely probe spatial structure and clumping in the fast wind of the central star of the H-rich planetary nebula NGC 6543 (HD 164963). Time-series data of the unsaturated PV λλ1118, 1128 resonance line P Cygni profiles provide a very sensitive diagnostic of variable wind conditio…
Studies of neutron stars at optical/IR wavelengths
Motch, C.; Rea, N.; De Luca, A. +7 more
In the last years, optical studies of Isolated Neutron Stars (INSs) have expanded from the more classical rotation-powered ones to other categories, like the Anomalous X-ray Pulsars (AXPs) and the Soft Gamma-ray Repeaters (SGRs), which make up the class of the magnetars, the radio-quiet INSs with X-ray thermal emission and, more recently, the enig…
Formation of Moving Magnetic Features and Penumbral Magnetic Fields with Hinode/SOT
Tsuneta, Saku; Shimizu, Toshifumi; Kubo, Masahito +10 more
Vector magnetic fields of moving magnetic features (MMFs) were well observed with the Solar Optical Telescope (SOT) aboard the Hinode satellite. We focused on the evolution of three MMFs with the SOT in this study. We found that an MMF having relatively vertical fields with the same polarity as the sunspot was detached from the penumbra around the…
On the Mass and Energy Loading of Extreme-UV Bright Points
McIntosh, Scott W.
We discuss the appearance of extreme-ultraviolet (EUV) bright points (BPs) in the analysis of long-duration observations in the He II 304 Å passband of the Solar and Heliospheric Observatory Extreme-ultraviolet Imaging Telescope (SOHO EIT). The signature of the observed 304 Å passband intensity fluctuations around the BPs suggests that the primary…
XMM-Newton Observations of Nova Sagittarii 1998
Hernanz, M.; Sala, G.
We report on X-ray observations of Nova Sagittarii 1998 (V4633 Sgr) performed with XMM-Newton at three different epochs, 934, 1083, and 1265 days after discovery. The nova was detected with the EPIC cameras at all three epochs, with emission spanning the whole energy range from 0.2 to 10 keV. The X-ray spectra do not change significantly at the di…
Kinematics of the Broad-Line Region in M81
Devereux, Nick; Shearer, Andrew
A new model is presented that explains the origin of the broad emission lines observed in the LINER/Seyfert nucleus of M81 in terms of a steady state spherically symmetric inflow, amounting to ~1×10-5 Msolar yr-1, which is sufficient to explain the luminosity of the active galactic nucleus (AGN). The emitting volum…
How to improve the maps of magnetic helicity injection in active regions?
Démoulin, Pascal; Pariat, Etienne; Nindos, Alexander
Magnetic helicity, a topological quantity which measures the twist, the writhe and the shear of a magnetic field, has recently appeared as a key quantity to understand some mechanisms of the solar activity such as Coronal Mass Ejections and flare onset. It is thus becoming of major importance to be able to compute magnetic helicity in active regio…
A Catalog of New M33 Star Clusters Based on Hubble Space Telescope WFPC2 Images
Lee, Myung Gyoon; Park, Won-Kee
We present the results of a survey for star clusters in M33 using HST WFPC2 archive images. We have found 104 star clusters, including 32 new ones, in the images of 24 fields that were not included in previous studies. Combining these with previous data in the literature, we increase the number of M33 star clusters found in the HST images to 242. …
A comparison of Cluster magnetic data with the Tsyganenko 2001 model
Davies, J. A.; Woodfield, E. E.; Dunlop, M. W. +2 more
As part of an investigation of the magnetic effects of external currents in the magnetosphere, we have compared two years of perigee Cluster data to the Tsyganenko 2001 (T01) field model. Cluster data are not included in the T01 database and therefore can be used to independently verify the model. The model performs very well in a global sense; ne…
Iron abundances of B-type post-asymptotic giant branch stars in globular clusters: Barnard29 in M13 and ROA5701 in ωCen
Dufton, P. L.; Keenan, F. P.; Thompson, H. M. A. +4 more
High-resolution optical and ultraviolet (UV) spectra of two B-type post-asymptotic giant branch (post-AGB) stars in globular clusters, Barnard29 in M13 and ROA5701 in ωCen, have been analysed using model atmosphere techniques. The optical spectra have been obtained with FEROS on the ESO 2.2-m telescope and the 2d-Coudé spectrograph on the 2.7-m Mc…