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Transition-Region Blinkers - II. Active-Region Properties
Harrison, R. A.; Parnell, C. E.; Bewsher, D.
The distribution and general properties of events identified in an active region that have the same characteristics as quiet-Sun blinkers are discussed and named `active-region blinkers'. The events are identified using an automated scheme `BLinker Identification Program' (BLIP) which was designed for and tested on quiet-Sun blinkers. Like quiet-S…
The Oldest Stars of the Extremely Metal-Poor Local Group Dwarf Irregular Galaxy Leo A
Greggio, Laura; Hopp, Ulrich; Schulte-Ladbeck, Regina E. +2 more
We present deep Hubble Space Telescope (HST) single-star photometry of Leo A in B, V, and I. Our new field of view is offset from the centrally located field observed by Tolstoy et al. in order to expose the halo population of this galaxy. We report the detection of metal-poor red horizontal branch stars, which demonstrate that Leo A is not a youn…
Optical Observations and Orbital Parameters of the Close DA plus dMe Binaries BPM 71214, EUVE J0720-31.7, BPM 6502, and EC 13471-1258
Vennes, Stéphane; Kawka, Adela; Koch, Rolf +1 more
We have obtained photometric and spectroscopic observations of the close DA plus dMe binaries BPM 6502 and EC 13471-1258, and spectroscopic observations of the close binaries BPM 71214 and EUVE J0720-31.7. We have updated the ephemerides of BPM 6502 and EUVE J0720-31.7 with the spectroscopic measurements and obtained periods of 0.20162 and 0.15074…
Dusty Acoustic Turbulence in the Nuclear Disks of Two LINER Galaxies NGC 4450 and NGC 4736
Elmegreen, Bruce G.; Elmegreen, Debra Meloy; Eberwein, Kate S.
The structure of dust spirals in the nuclei of the SAab-type LINER galaxies NGC 4450 and NGC 4736 is studied using archival Hubble Space Telescope Planetary Camera images. The spirals are typically only several hundredths of a magnitude fainter than the neighboring disks, so unsharp-mask techniques are used to highlight them. The ambient extinctio…
GRB 010921: Localization and Observations by the High Energy Transient Explorer Satellite
Sakamoto, T.; Yamauchi, M.; Cline, T. +36 more
On 2001 September 21 at 05:15:50.56 UT, the French Gamma Telescope (FREGATE) on the High Energy Transient Explorer (HETE) detected a bright gamma-ray burst (GRB). The burst was also seen by the X-detector on the Wide-field X-ray Monitor (WXM) instrument and was therefore well localized in the X-direction however, the burst was outside the fully co…
A conspicuous tangential alignment of galaxies in a STIS Parallel Shear Survey field: A new dark-lens candidate?
White, S. D. M.; Fosbury, R. A. E.; Schneider, P. +6 more
We report the serendipituous discovery of a conspicuous alignment of galaxies in a field obtained through the STIS Parallel Shear Survey. This project collects randomly distributed 50'' x 50'' fields to investigate the cosmic shear effect on this scale. Analyzing the parallel observations having the Seyfert galaxy NGC 625 as primary target, we rec…
Photoelectric Charging of Submicron Aerosols and Macromolecules in the Titan Haze
McKay, Christopher P.; Bakes, E. L. O.; Bauschlicher, Charles W.
We quantify the charge states of submicrometer aerosols and aromatic macromolecules in Titan's organic haze. The aerosol charge is balanced between the recombination of positive ions with the aerosol plus the ejection of electrons from the aerosol via the UV-driven photoelectric effect and the recombination of electrons with the aerosol. During th…
Far Ultraviolet Spectroscopic Explorer Observations of the Seyfert 1.5 Galaxy NGC 5548 in a Low State
Zheng, W.; Kriss, G. A.; Hutchings, J. B. +4 more
We present far-ultraviolet spectra of the Seyfert 1.5 galaxy NGC 5548 obtained in 2000 June with the Far Ultraviolet Spectroscopic Explorer (FUSE). Our data span the observed wavelength range 915-1185 Å at a resolution of ~20 km s-1. The spectrum shows a weak continuum and emission from O VI λλ1032, 1038, C III λ977, and He II λ1085. Th…
The OIV and SIV intercombination lines in the ultraviolet spectra of astrophysical sources
Doyle, J. G.; Madjarska, M. S.; Mathioudakis, M. +8 more
New electron density diagnostic line ratios are presented for the OIV 2s22p 2P-2s2p24P and SIV 3s23p 2P-3s3p24P intercombination lines around 1400Å. A comparison of these with observational data for the symbiotic star RR Telescopii (RR Tel), obtained with the Space Telescope Imaging…
Core and Large-Scale Structure of the 2000 November 24 X-Class Flare and Coronal Mass Ejection
Yang, Guo; Wang, Haimin; Yurchyshyn, Vasyl +2 more
In this paper, we present three important aspects of the X1.8 flare and the associated coronal mass ejection (CME) that occurred on 2000 November 24: (1) The source of the flare is clearly associated with a magnetic channel structure, as was noted in a study by Zirin & Wang , which is due to a combination of flux emergence inside the leading e…