Search Publications
Observations of QSO J2233-606 in the Southern Hubble Deep Field
Webb, J. K.; Drinkwater, M. J.; Sealey, K. M.
The Hubble Deep Field South (HDF-S) Hubble Space Telescope (HST) observations are expected to begin in 1998 October. We present a composite spectrum of the QSO in the HDF-S field covering UV/optical/near-IR wavelengths, obtained by combining data from the Australian National University 2.3 m telescope with STIS on the HST.1 This intermediate-resol…
Morphological Changes, Evidence for a Collimating Disk, and Extremely Young Jetlike Components in the Planetary Nebula IC 4997
Miranda, Luis F.; Torrelles, José M.
We present VLA-A radio continuum observations at 3.6 cm and 2 cm of the extremely young, double-shell planetary nebula IC 4997. A comparison of the new 3.6 cm map with that obtained in 1995 July shows that morphological changes have occurred in the nebula in ~=1.3 yr. These changes reveal themselves by the presence in the outer shell of several ne…
New Light Synthesis and Spectrum Synthesis Constraints on a Model for β Lyrae
Harmanec, P.; Hubeny, I.; Linnell, A. P.
A suite of programs that calculates both synthetic light curves and synthetic spectra for a binary system with an optically thick accretion disk has been applied for the first time to β Lyrae A. Our results demonstrate that the standard accretion disk model by Hubeny & Plavec shows significant residuals from observations, both photometric and …
Carbon and Oxygen Depletion and Extinction in the Translucent Cloud toward HD 24534 (X Persei)
Snow, Theodore P.; van Dishoeck, Ewine F.; Black, John H. +3 more
Recent studies of the gas-phase abundances of carbon and oxygen in diffuse clouds have suggested that the depletions of both elements are invariant and independent of extinction curve properties. We show, however, that in the line of sight toward HD 24534 (X Persei), the depletion of carbon is at least a factor of 3 greater than in the diffuse clo…
Mid-Infrared Emission Features in the Interstellar Medium: Feature-to-Feature Flux Ratios
Lu, Nanyao Y.
Using a limited but representative sample of sources in the interstellar medium of our Galaxy with published spectra from the Infrared Space Observatory, we analyze the flux ratios between the major mid-IR emission features (EFs) centered around 6.2, 7.7, 8.6, and 11.3 µm, respectively. In a flux ratio-to-flux ratio plot of EF(6.2 µm)/…
A Statistical Treatment of the Gamma-Ray Burst ``No Host Galaxy'' Problem. I. Methodology
Hartmann, Dieter H.; Band, David L.
If gamma-ray bursts originate in galaxies at cosmological distances, the host galaxy should be detected if a burst error box is searched deeply enough; are the host galaxies present? We present and implement a statistical methodology that evaluates whether the observed galaxy detections in a burst's error box are consistent with the presence of th…
The STIS Parallel Survey: Introduction and First Results
Ferguson, Henry C.; Baum, Stefi A.; Gardner, Jonathan P. +15 more
The installation of the Space Telescope Imaging Spectrograph (STIS) on the Hubble Space Telescope (HST) allows for the first time two-dimensional optical and ultraviolet slitless spectroscopy of faint objects from space. The STIS Parallel Survey (SPS) routinely obtains broadband images and slitless spectra of random fields in parallel with HST obs…
First VLA Observations of Nonthermal Metric Bursts Associated with Coronal Mass Ejections Detected by the Solar and Heliospheric Observatory
St. Cyr, O. C.; Thompson, B. J.; Willson, R. F. +2 more
We present the first observations of nonthermal decimetric burst emission of the Sun using the new 400 cm (74 MHz) system at the VLA. Our VLA observations were carried out in collaboration with the Large Angle Spectroscopic Coronagraph (LASCO) and the Extreme-Ultraviolet Imaging Telescope (EIT) on board the Solar and Heliospheric Observatory space…
Space Telescope Imaging Spectrograph Observations of the Interstellar Velocity Structure and Chemical Composition toward the Carina Nebula
Walborn, Nolan R.; Jenkins, Edward B.; Sembach, Kenneth R. +9 more
We have observed the O-type star CPD -59°2603 in the Carina Nebula with the Space Telescope Imaging Spectrograph near-UV and far-UV high-resolution echelles, at a resolving power of ~110,000 (FWHM) and S/N ~ 30. This sight line has complex velocity and excitation structure in the interstellar absorption lines, corresponding to three distinct regio…
Supra-Horizontal-Branch Stars and Population Gradients in the Galactic Center Globular Cluster NGC 6522
Rich, R. M.; King, I. R.; Paresce, F. +3 more
We have imaged the core of NGC 6522 and an adjacent field 1' north in the U and B passbands using the (pre-COSTAR) HST Planetary Camera. We find 13 stars located 1.5 mag above the horizontal branch. These supra-horizontal-branch (SHB) stars have not been noted previously in NGC 6522, although they occur in other globular clusters. The SHB stars' r…