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Dust Morphology of Hidden Broad-Line Region and Non-Hidden Broad-Line Region Seyfert 2 Galaxies
Hwang, Chorng-Yuan; Yu, Po-Chieh
We investigate the nuclear dust properties of hidden broad-line region (HBLR) and non-HBLR Seyfert 2 galaxies. Optical images obtained from the Hubble Space Telescope for a selected sample of HBLR and non-HBLR Seyfert 2 galaxies are fitted with the Galfit package to probe the inner structures of these galaxies within the central 1 kpc regions. Mos…
The Discovery of Oxygen-rich Chromospheres in Two Massive DQ White Dwarfs
Provencal, J. L.; Shipman, H. L.; MacDonald, James
We present HST observations of the massive DQ white dwarfs G227-5 and G35-26 in which we find the first clear evidence of chromospheric activity in cool field white dwarfs. The chromospheric spectra, obtained over a very narrow wavelength range, show lines of the usually expected species O I, N I, C II, and possibly Si III and Mg II. The O I/C II …
Spin-resolved Far-Ultraviolet Observations of the Magnetic White Dwarf in YY Draconis
Szkody, Paula; Sion, Edward M.; Hoard, D. W. +1 more
We observed the intermediate polar YY Draconis with the Far Ultraviolet Spectroscopic Explorer (FUSE), yielding an average far-UV spectrum, as well as spectra and spectrophotometric light curves resolved on the spin phase of the white dwarf in this system. We utilized the BINSYN software suite to calculate model spectra based on a simple system mo…
Systematic motions in the galactic plane found in the Hipparcos catalogue using Herschel's Method
Vieira, K.; Abad, C.
Two motions in the galactic plane have been detected and characterized, based on the determination of a common systematic component in Hipparcos catalogue proper motions. The procedure is based only on positions, proper motions and parallaxes, plus a special algorithm which is able to reveal systematic trends. Our results come from two stellar sam…
Cosmic Shear from STIS pure parallels. III. Analysis of Cycle 9 pure parallels
Fosbury, R. A. E.; Schneider, P.; Erben, T. +4 more
Following the detection of a cosmic shear signal at the 30'' scale using archival parallel data from the STIS CCD camera onboard HST in the previous paper of this series, we analyzed a larger data set obtained from an HST GO pure parallel program. Although this data set is considerably larger than the one analyzed previously, we do not obtain a si…
Large-scale velocity fluctuations in polar solar wind
Bavassano, B.; Bruno, R.; D'Amicis, R.
The 3-D structure of the solar wind varies dramatically along the Sun's activity cycle. In the present paper we focus on some properties of the polar solar wind. This is a fast, teneous, and steady flow (as compared to low-latitude conditions) that fills the high-latitude heliosphere at low solar activity. The polar wind has been extensively inves…
The X-ray activity of the slowly rotating G giant δ CrB
Gondoin, P.
δ CrB is a single G giant whose distinctive characteristics include an X-ray luminosity exceptionally high for a slowly rotating star. δ CrB was observed in March 2003 by the {XMM{-}Newton} observatory. The X-ray spectra of δ CrB are described by a MEKAL plasma model with two components at 6.5 ×106 K and 107 K. Series of line…
The Chinese ground-based instrumentation in support of the combined Cluster/Double Star satellite measurements
Wu, J.; Liu, R. -Y.; Yang, H. -G. +10 more
Ground-based observations can be used to provide substantial support for Cluster/Double Star measurements and greatly enhance the mission's scientific return. There are six Chinese ground stations involved in coordinated cluster/Double Star and ground-based instrument observations. Among them, the Chinese Zhongshan Station in Antarctica and the Ye…
Spectral Evolution of a Luminous Compact X-Ray Source in NGC 253 with Chandra and XMM-Newton Observatories
Makishima, Kazuo; Takahashi, Tadayuki; Kubota, Aya +2 more
Spectral studies of a luminous X-ray source, NGC 253 X21, are presented based on archival Chandra and XMM-Newton data. The Chandra observation on 1999 December 16 detected the source at a bolometric luminosity of 0.3 × 1039 erg s-1 (assuming isotropic emission), while an XMM-Newton observation on 2000 June 3 revealed a short-…
Analysis of Cluster spacecraft potential during active control
Escoubet, C. P.; André, M.; Décréau, P. M. E. +4 more
The floating potential of a spacecraft is determined by an equilibrium between photo-electron emission from the sunlit spacecraft surfaces and the plasma electron current, while other currents play a secondary role. On the Cluster spacecraft, the presence of the experiment ASPOC to control the potential by an ion beam with currents up to several t…