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A revisit to agglomerates of early-type Hipparcos stars
Caballero, J. A.; Dinis, L.
% We study the spatial structure and sub-structure of regions rich in {Hipparcos} stars with blue B_T-V_T colours. These regions, which comprise large stellar complexes, OB associations, and young open clusters, are tracers of on-going star formation in the Galaxy. The DBSCAN (Density-Based Spatial Clustering of Applications with Noise) data clust…
Exploratory Study of the X-Ray Properties of Quasars with Intrinsic Narrow Absorption Lines
Charlton, Jane C.; Eracleous, Michael; Misawa, Toru +1 more
We have used archival Chandra and XMM-Newton observations of quasars hosting intrinsic narrow UV absorption lines (intrinsic NALs) to carry out an exploratory survey of their X-ray properties. Our sample consists of three intrinsic NAL quasars and one "mini-BAL" quasar, plus four quasars without intrinsic absorption lines for comparison. These wer…
A HST study of the environment of the Herbig Ae/Be star LkHα 233 and its bipolar jet
Ray, T. P.; Eislöffel, J.; Bacciotti, F. +3 more
Context: LkHα 233 is a Herbig Ae/Be star with a collimated bipolar jet. As such, it may be a high-mass analogue to the classical T Tauri stars and their outflows.
Aims: We investigate optical forbidden lines along the LkHα 233 jet to determine physical parameters of this jet (electron density ne, hydrogen ionisation fraction xe…
CCD Charge Injection Structure at Very Small Signal Levels
Prigozhin, Gregory; Kissel, Steve; Lamarr, Beverly +2 more
Lensing Probabilities for Spectroscopically Selected Galaxy-Galaxy Strong Lenses
Keeton, Charles R.; Dobler, Gregory; Bolton, Adam S. +1 more
Spectroscopic galaxy-galaxy lens searches are presently the most prolific method of identifying strong lens systems in large data sets. We study the probabilities associated with these lens searches, namely the probability of identifying a candidate with rogue [O II] emission lines in a galaxy's spectrum, and the probability that the candidate wil…
Deviations from the Flux-Recurrence Time Relationship in GS 1826-238: Potential Transient Spectral Changes
Rothschild, Richard E.; Galloway, Duncan K.; Homer, Lee +1 more
The low-mass X-ray binary GS 1826-238 is presently unique for its consistently regular bursting behavior. In previous Rossi X-Ray Timing Explorer (RXTE) measurements between 1997 November and 2002 July, this source exhibited (nearly) limit-cycle bursts with recurrence times that decreased proportionately as the persistent flux increased. Here we r…
Dielectric properties of the Martian south polar layered deposits: MARSIS data inversion using Bayesian inference and genetic algorithm
Nielsen, Erling; Zhang, Zhenfei; Plaut, Jeffrey J. +3 more
Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) has offered abundant data, which have been used to estimate dielectric properties of the south polar layered deposits (SPLD) of Mars. This paper presents a new way to invert the data to estimate the dielectric properties of the SPLD. A total of 4364 measurements were analyzed. The…
Non-Local Thermodynamic Equilibrium Model of NGC 6543's Central Star and Its Relation to the Surrounding Planetary Nebula
Hillier, D. J.; Richer, M. G.; Peimbert, M. +3 more
We analyze the chemical composition of the central star of the planetary nebula NGC 6543 based on a detailed NLTE model of its stellar wind. The logarithmic abundances by number are H = 12.00, He = 11.00, C = 9.03, N = 8.36, O = 9.02, Si = 8.19, P = 5.53, S = 7.57, and Fe = 7.24. Compared with the solar abundances, most of the elements have solar …
The Chandra Small Magellanic Cloud Wing Survey - the search for X-ray binaries
Coe, M. J.; McBride, V. A.; McGowan, K. E. +6 more
We have detected 523 sources in a survey of the Small Magellanic Cloud (SMC) Wing with Chandra. By cross-correlating the X-ray data with optical and near-infrared catalogues, we have found 300 matches. Using a technique that combines X-ray colours and X-ray to optical flux ratios, we have been able to assign preliminary classifications to 265 of t…
Cyclic behavior of solar full-disk activity
Li, K. J.; Gao, P. X.; Li, Q. X. +1 more
In order to describe the cyclic behavior of solar full-disk activity (the surface magnetic fields, filaments, the green Fe XIV, 5303Å corona local maxima intensities, and torsional oscillations), we propose a new concept, a "full-disk activity cycle," which consists of two successive normal cycles: a high-latitude activity cycle following a low-la…