Search Publications
On the importance of the few most massive stars: The ionizing cluster of NGC 588
Vílchez, J. M.; González Delgado, R. M.; Cerviño, M. +3 more
We present the results of a double analysis of the ionizing cluster in
Magnetohydrodynamic Models of the Bipolar Knotty Jet in Henize 2-90
Lee, Chin-Fei; Sahai, Raghvendra
A remarkably linear, bipolar, knotty jet was recently discovered in Hen 2-90, an object classified as a young planetary nebula. Using two-dimensional, magnetohydrodynamic simulations, we investigate periodic variations in jet density and velocity as the mechanism for producing the jet and its knotty structures. From a detailed comparison between t…
Low-energy particle response to CMEs during the Ulysses solar maximum northern polar passage
Lario, D.; Reisenfeld, D. B.; Roelof, E. C. +2 more
Near the end of 2001, the Ulysses spacecraft transited the northern polar regions of the heliosphere, above heliographic latitudes of 71°N. During this period (September-November 2001), Ulysses remained immersed in polar coronal hole solar wind flow and observed five intense solar energetic particle events and five interplanetary coronal mass ejec…
Cometary Ions Trapped in a Coronal Mass Ejection
Geiss, J.; Jones, G. H.; McComas, D. J. +5 more
Ion tails of comets are known to extend radially away from the Sun over very large distances. Crossing these tails by spacecraft not specifically targeted to intercept them was believed to be extremely improbable, since that requires precise angular alignment of the spacecraft with a comet. We report here the fortuitous detection of cometary ions …
Accretion and Outflow in the Active Galactic Nucleus and Starburst of NGC 5135
Heckman, T. M.; Levenson, N. A.; Weaver, K. A. +2 more
Observations of the Seyfert 2 and starburst galaxy NGC 5135 with the Chandra X-Ray Observatory demonstrate that both of these phenomena contribute significantly to its X-ray emission. We spatially isolate the active galactic nucleus (AGN) and demonstrate that it is entirely obscured by column density NH>1024 cm-2
Physical interpretation of the NGC 7469 UV/X-ray variability
Maraschi, L.; Nandra, K.; Petrucci, P. O. +1 more
We present a re-analysis of the simultaneous ∼30 day IUE/XTE observation of NGC 7469 done in 1996. Our main progress in this paper, in comparison to previous spectral analyses (Nandra et al. \cite{nan98,nan00}), is to adopt and fit directly to the data a detailed model of the Comptonized spectrum. This firstly allows one to fit simultaneously the …
Heavy Element Abundances in Late-B and Early-A Stars. I. Co-Added IUE Spectra of HgMn Stars
Leckrone, D. S.; Wahlgren, G. M.; Adelman, S. J. +2 more
Very heavy elements (Pt, Au, Hg, Tl, and Bi) are found to be enhanced in the atmospheres of the chemically peculiar stars of the upper main sequence by up to a million times the solar system levels. Such enhancements are believed to result from atmospheric dynamics (i.e., diffusion) rather than scenarios that dredge up nuclear-processed material t…
XMM-Newton Study of A3562 and Its Immediate Shapley Environs
Finoguenov, A.; Kaastra, J. S.; de Plaa, J. +2 more
Using a mosaic of six XMM-Newton observations, we study the hydrodynamic state of A3562, a cluster in the center of the Shapley supercluster. The X-ray image reveals a sharp surface brightness gradient within the core of A3562, a 200 kpc ridge extending to the southwest. A nearby group, SC 1329-313, imaged within this program also exhibits a tail …
Molecular and dust features of 29 SiC carbon AGB stars
He, Jinhua; Yang, Xiaohong; Chen, Peisheng
We have reduced and analyzed the Infrared Space Observatory (ISO) Short-Wavelength Spectrometer (SWS) spectra of 29 infrared carbon stars with a silicon carbide feature at 11.30 µm, 17 of which have not been previously published. Absorption or emission features of C2, HCN, C2H2, C3 and silicon carb…
XMM-Newton observations of three high-redshift radio galaxies
Lawrence, C. R.; Hardcastle, M. J.; Birkinshaw, M. +2 more
We present the results of XMM-Newton observations of three powerful high-redshift radio galaxies 3C184, 3C292 and 3C322. Although none of the sources lies in as rich an X-ray-emitting environment as is seen for some powerful radio galaxies at low redshift, the environments provide sufficient pressure to confine the radio lobes. The weak gas emissi…