Search Publications
Hubble Space Telescope Ultraviolet and Ground-based Optical Spectropolarimetry of IRAS Quasi-stellar Objects: Dusty Scattering in Luminous Active Galactic Nuclei
Gordon, Karl D.; Hines, Dean C.; Sitko, Michael L. +4 more
We present UV and optical spectropolarimetry of two highly polarized IRAS-selected quasi-stellar objects (QSOs), IRAS 13349+2438 and the broad absorption line QSO (BALQSO) IRAS 14026+4341. The polarization in both objects rises rapidly toward the blue, peaks near 3000 Å in the rest frame and remains nearly constant for shorter wavelengths. The res…
Model Atmospheres with Individualized Abundances
Piskunov, N.; Kupka, F.
We describe a new method for computing opacity distribution functions (ODFs) for model atmosphere calculations. The method is tailored to model the atmospheres of individual stars on a modern workstation. Our goal is the computation of model atmospheres for stars with abundances significantly different from the solar or scaled solar composition ty…
4U 2206+54: An Unusual High-Mass X-Ray Binary with a 9.6 Day Orbital Period But No Strong Pulsations
Corbet, Robin H. D.; Peele, Andrew G.
Rossi X-Ray Timing Explorer (RXTE) All-Sky Monitor observations of the X-ray source 4U 2206+54, previously proposed to be a Be star system, show the X-ray flux to be modulated with a period of approximately 9.6 days. If the modulation is due to orbital variability, then this would be one of the shortest orbital periods known for a Be star X-ray so…
Results from UVCS and LASCO Observation of the Sungrazing Comet C/2000 C6
Raymond, J. C.; Wu, R.; Uzzo, M. +4 more
During 2000 February 9-10, the Large Angle Spectrometric Coronagraph and Ultraviolet Coronal Spectrometer (UVCS) instruments aboard the Solar and Heliospheric Observatory observed comet C/2000 C6, a member of the Kreutz family of sungrazing comets. A tail nearly 0.5 Rsolar in length was detected in Lyα emission. UVCS was able to observe…
On the Unresolved Fine Structures of the Solar Upper Atmosphere. IV. The Interface with the Chromosphere
Wilhelm, K.; Dammasch, I. E.; Feldman, U.
An important objective of the solar physics community is the unambiguous determination of the morphology of the fine structures of the solar upper atmosphere in quiet-Sun and coronal hole regions and the relationship of the cold chromosphere to the hot corona. Recently the Solar Ultraviolet Measurements of Emitted Radiation spectrometer on board t…
Hα Imaging with Hubble Space Telescope-NICMOS of an Elusive Damped Lyα Cloud at z=0.6
Charlton, Jane C.; Bouché, Nicolas; Bershady, Matthew A. +3 more
Despite previous intensive ground-based imaging and spectroscopic campaigns and wideband Hubble Space Telescope (HST) imaging of the z=0.927 QSO 3C 336 field, the galaxy that hosts the damped Lyα system along this line of sight has eluded detection. We present a deep narrowband Hα image of the field of this zabs=0.656 damped Lyα absorbe…
The Case against Cold, Dark Chromospheres
Kalkofen, Wolfgang
Is the solar chromosphere always hot, with relatively small temperature variations (δT/T~0.1), or is it cold most of the time, with temperature fluctuations that reach δT/T~10 at the top of the chromosphere? Or, equivalently, is the chromosphere heated continually or only for a few seconds once every 3 minutes? Two types of empirical model, one es…
Ultraviolet Coronagraph Spectrometer Observations of a High-Latitude Coronal Hole with High Oxygen Temperatures and the Next Solar Cycle Polarity
Cranmer, S. R.; Kohl, J. L.; Miralles, M. P.
We announce the resurgence of extreme ion properties in a large, high-latitude coronal hole observed above the north heliographic pole in 2001 February at solar maximum. The observations were taken with the Ultraviolet Coronagraph Spectrometer on the Solar and Heliospheric Observatory. These observations are part of an ongoing campaign to determin…
Observation of the Halo of NGC 3077 near the ``Garland'' Region Using the Hubble Space Telescope
Madore, Barry F.; Sakai, Shoko
We report the detection of upper main-sequence stars and red giant branch stars in the halo of an amorphous galaxy, NGC 3077. The observations were made using the Wide Field Planetary Camera 2 on board the Hubble Space Telescope. The red giant branch luminosity function in the I band shows a sudden discontinuity at I=24.0+/-0.1 mag. Identifying th…
EIT and SXT Observations of a Quiet-Region Filament Ejection: First Eruption, Then Reconnection
Moore, Ronald L.; Sterling, Alphonse C.; Thompson, Barbara J.
We observe a slow-onset quiet-region filament eruption with the EUV Imaging Telescope (EIT) on the Solar Heliospheric Observatory (SOHO) and the soft X-ray telescope (SXT) on Yohkoh. This event occurred on 1999 April 18 and was likely the origin of a coronal mass ejection detected by SOHO at 08:30 UT on that day. In the EIT observation, one-half o…