Search Publications
Solar Disappearing Filament Inside a Coronal Hole
Hudson, H. S.; Chertok, I. M.; Obridko, E. I. +2 more
Based on Yohkoh/SXT, SOHO/EIT images and movies, as well as on Hα, He I 10830 Å heliograms and other relevant data, we analyze an event of 1999 December 28, which is interesting in at least two aspects. (1) A major horseshoe-shaped Hα filament appeared to be located within a large transequatorial coronal hole (CH) in the eastern hemisphere. (2) Th…
Discovery of 15 Second Oscillations in Hubble Space Telescope Observations of WZ Sagittae following the 2001 Outburst
Knigge, C.; Marsh, T. R.; Long, K. S. +3 more
We report the discovery of 15 s oscillations in ultraviolet observations of WZ Sagittae obtained with the Hubble Space Telescope approximately 1 month after the peak of the 2001 outburst. This is the earliest detection of oscillations in WZ Sge following an outburst and the first time that a signal near 15 s has been seen to be dominant. The oscil…
Imaging and Spatially Resolved Spectroscopy of AFGL 2688 in the Thermal Infrared Region
Kobayashi, Naoto; Terada, Hiroshi; Goto, Miwa +1 more
We present ground-based high-resolution (~0.3") imaging of AFGL 2688 at L' (3.8 µm) and M' (4.7 µm). A wealth of structure in the central region is revealed as a consequence of less extinction in the thermal infrared. A clear border in the southern lobe at L' corresponds to the edge of the heavily obscured region in visible, indicating…
Mid-Infrared and CO Observations of the Infrared/X-Ray Luminous Seyfert 1 Galaxy NGC 985: The Making or Breaking of a ULIRG?
Appleton, P. N.; Charmandaris, V.; Gao, Yu +4 more
We describe Infrared Space Observatory (ISO)1 and BIMA observations of the z=0.04 Seyfert 1 ring galaxy NGC 985 which suggest close parallels with some quasar host galaxies. NGC 985 contains two closely spaced nuclei embedded in an R1/4-law stellar bulge and an outer ring, evidence of an ongoing merger. The system contains ~1.8×101…
Emission of Positron Annihilation Line Radiation by Clusters of Galaxies
Loeb, Abraham; Furlanetto, Steven R.
Clusters of galaxies are enriched with positrons from jets of active galactic nuclei (AGNs) or from the interaction of cosmic rays with the intracluster gas. We follow the cooling of these positrons and show that their eventual annihilation with cluster electrons yields a narrow annihilation line. Unlike annihilation in the interstellar medium of …
Space Telescope Imaging Spectrograph Ultraviolet Spectroscopy of Early B Supergiants in M31
Bresolin, Fabio; Kudritzki, Rolf-Peter; Urbaneja, Miguel A. +4 more
We analyze Space Telescope Imaging Spectrograph (STIS) spectra in the 1150-1700 Å wavelength range obtained for six early B supergiants in the neighboring galaxy M31. Because of their likely high (nearly solar) abundance, these stars were originally chosen to be directly comparable to their Galactic counterparts and represent a much needed additio…
The 12C/13C Ratio in the Planetary Nebula NGC 3242 from Hubble Space Telescope STIS Observations
Marconi, Alessandro; Tosi, Monica; Stanghellini, Letizia +2 more
We present high-resolution Hubble Space Telescope ultraviolet spectroscopy of NGC 3242, the only planetary nebula with a measured abundance of 3He. The Space Telescope Imaging Spectrograph has been used to observe the C III multiplet near 1908 Å. The presence of 12C and 13C lines at these wavelengths allows a direc…
The Photospheric Absorption Lines in the Ultraviolet Spectrum of the Multiple System HD 5980
Koenigsberger, Gloria; Kurucz, Robert L.; Georgiev, Leonid
We search for radial velocity variations in the ultraviolet spectra of the erupting Wolf-Rayet/luminous blue variable system HD 5980, located in the Small Magellanic Cloud. We obtain an average radial velocity of 22+/-22 km s-1 for five observations in 1999 at different orbital phases, -39+/-24 km s-1 for one observation in 2…
Will Jets Identify the Progenitors of Type Ia Supernovae?
Livio, Mario; Riess, Adam; Sparks, William
We use the fact that a Type Ia supernova has been serendipitously discovered near the jet of the active galaxy 3C 78 to examine the question of whether jets can enhance accretion onto white dwarfs. One interesting outcome of such a jet-induced accretion process is an enhanced rate of novae in the vicinity of jets. We present results of observation…
The Central Binary and Surrounding Nebula of the Symbiotic Star V1016 Cygni
Eyres, S. P. S.; Bode, M. F.; Taylor, A. R. +3 more
We present Hubble Space Telescope (HST) Wide Field Planetary Camera 2 images of the symbiotic star V1016 Cygni that, for the first time, directly explore the inner regions of the nebula to AU scales at optical wavelengths. They also suggest that the [O III] λλ4959, 5007 emission takes place in a bipolar outflow. We use these images to determine th…