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Stars of Extragalactic Origin in the Solar Neighborhood
Borkova, T. V.; Marsakov, V. A.
For 77 main-sequence F-G stars in the solar neighborhood with published iron, magnesium, and europium abundances determined from high-dispersion spectra and with the ages estimated from theoretical isochrones, we calculated the spatial velocities using Hipparcos data and the Galactic orbital elements. A comparison with the orbital elements of the …
Photoionization model analysis of the planetary nebula Hu1-2
Pottasch, S. R.; Feibelman, W. A.; Hyung, S.
We have obtained high resolution optical spectra of the planetary nebula
A Hubble Space Telescope STIS Observation of VW Hydri at the Exact Far-Ultraviolet Onset of an Outburst
Szkody, Paula; Sion, Edward M.; Gänsicke, Boris T. +1 more
We present an analysis of Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph data of VW Hyi that we acquired 14 days after a superoutburst. At the time of our observation, the system appears to be going into outburst with the longest wavelengths increasing in flux by a factor of 5 while the shortest wavelengths increase by only a fa…
The Luminous Erupting Dwarf Nova CV 1 in the Dense Globular Cluster M15
Zurek, David R.; Hinkley, Sasha; Bond, Howard E. +2 more
Despite decades-old predictions of the expected presence of dozens of cataclysmic variables in the cores of globular clusters, the number of irrefutable, outbursting candidates is still barely a handful. Using multiwavelength, multiepoch Hubble Space Telescope images, we have produced outburst and quiescence light curves for the recently discovere…
The narrow-line quasar NAB 0205+024 observed with XMM-Newton
Brandt, W. N.; Vaughan, S.; Fabian, A. C. +2 more
The XMM-Newton observation of the narrow-line quasar NAB 0205+024 reveals three striking differences since it was last observed in X-rays with ASCA. First, the 2-10 keV power law is notably steeper. Secondly, a hard X-ray flare is detected, very similar to that seen in I Zw 1. Thirdly, a strong and broad emission feature is detected with the bulk …
Spectrum of Solar Type I Continuum Noise Storm in the 50-80 MHz Band and Plasma Characteristics in the Associated Source Region
Sundaram, G. A. Shanmugha; Subramanian, K. R.
Continuum observations of a solar noise storm in the frequency range of 50-80 MHz observed with the Gauribidanur radio spectrograph during 2000 September 26 and 27 are presented here. The radio spectral index of the noise storm continuum in the 50-80 MHz band is found to be ~3.65 during the above period. The noise storm continuum radiation is expl…
Detecting compact dark matter in galaxy clusters via gravitational microlensing: A2218 and A370
Kneib, J. -P.; Lewis, G. F.; Ibata, R. A. +1 more
After decades of searching, the true nature of dark matter still eludes us. One potential probe of the form of dark matter in galaxy clusters is to search for microlensing variability in the giant arcs and arclets. In this paper, a simple method is introduced to characterize pixel variability in the limit of high optical depth to microlensing. Exp…
Comparing Chandra and SIRTF Observations for Obscured Starbursts and Active Galactic Nuclei at High Redshift
Zezas, A.; Charmandaris, V.; Weedman, D.
Tracking the star formation rate to high redshifts requires knowledge of the contribution from both optically visible and obscured sources. The dusty, optically obscured galaxies can be located by X-ray and infrared surveys. To establish criteria for selecting such sources based only on X-ray and infrared surveys, we determine the ratio of infrare…
Conjugate comparison of Super Dual Auroral Radar Network and Cluster electron drift instrument measurements of E × B plasma drift
Balogh, A.; Tsyganenko, N. A.; Quinn, J. M. +6 more
Much of our current understanding of magnetospheric electrodynamics is based on the assumption that magnetic field lines often behave as electrostatic equipotentials. This assumption has allowed hemispheric patterns of ionospheric convection to be interpreted in terms of the large-scale circulation of plasma in the magnetosphere. However, the exte…
Estimation of the Three-Dimensional Space Speed of a Coronal Mass Ejection Using Metric Radio Data
Ramesh, R.; Kathiravan, C.
We present an independent method for obtaining the three-dimensional space speed of a coronal mass ejection in the lower solar atmosphere through ray-tracing analysis of the thermal radio counterpart of its frontal loop in the metric wavelength range. The scheme was tested on the halo event observed on 1998 January 21, obtaining an estimated space…