Search Publications
The FUSE Spectrum of the Planetary Nebula SwSt 1: Evidence for Inhomogeneities in the Gas and Dust
Redfield, Seth; Dinerstein, Harriet L.; Bowers, C. W. +1 more
We present Far Ultraviolet Spectroscopic Explorer (FUSE) observations of the young, compact planetary nebula (PN) SwSt 1 along the line of sight to its central star HD 167362. We detect circumstellar absorption lines from several species against the continuum of the central star. The physical parameters of the nebula derived from the FUSE data dif…
Faint BVRI Photometric Sequences in Selected Fields
Saha, A.; Dolphin, A. E.; Thim, F. +1 more
The results from work done to extend the Johnson-Cousins BVRI photometric standard sequence to faint levels of V~21 mag in compact fields is presented. Such calibration and extension of sequences is necessary to fill a calibration gap if reliable photometry from modest aperture telescopes in space (e.g., the Hubble Space Telescope) or terrestrial …
Cool Customers in the Stellar Graveyard. I. Limits to Extrasolar Planets Around the White Dwarf G29-38
Debes, John H.; Woodgate, Bruce E.; Sigurdsson, Steinn
We present high-contrast images of the hydrogen white dwarf G29-38 taken in the near-infrared with the Hubble Space Telescope and the Gemini North Telescope as part of a high-contrast imaging search for substellar objects in orbit around nearby white dwarfs. We review the current limits on planetary companions for G29-38, the only nearby white dwa…
Measurement of Noisy Absorption Lines Using the Apparent Optical Depth Technique
Savage, Blair D.; Fox, Andrew J.; Wakker, Bart P.
To measure the column densities of interstellar and intergalactic gas clouds using absorption-line spectroscopy, the apparent optical depth (AOD) technique of Savage & Sembach can be used instead of a curve-of-growth analysis or profile fit. We show that the AOD technique, while an excellent tool when applied to data with good signal-to-noise …
Electron density along a coronal loop observed with CDS/SOHO
Doyle, J. G.; Madjarska, M. S.; Ugarte-Urra, I. +1 more
The analysis of a coronal loop observed by CDS and EIT on board SOHO is presented. The loop was situated above the North-East limb at a latitude of ~48°, being clearly visible in the hottest lines of the dataset, Fe xvi 360.76 Å, i.e. greater than 2 000 000 K. The cooler lines in the sample (i.e. O v 629.73 Å and He i 584.35 Å) showed only a brigh…
Comparison of Star Clusters With and Without Wolf-Rayet Stars in Wolf-Rayet Galaxies
Kobulnicky, Henry A.; Dufour, Reginald J.; Buckalew, Brent A.
We compare the properties of young star clusters with and without Wolf-Rayet (W-R) stars in W-R galaxies using optical, near-infrared imagery and optical spectroscopy. Our work identifies the clusters with W-R stars in these galaxies for the first time. With this information, comparisons of clusters with and without W-R stars are now possible, ena…
X-ray observations of the old open stellar cluster NGC 188
Gondoin, P.
I present the analysis results from XMM-Newton observations of the old open stellar cluster NGC 188, which has an age of about 7 Gyr and a near solar metallicity. 58 X-ray sources were detected in the field of view of the EPIC MOS and pn cameras, and 46 sources are new X-ray detections. Visible counterparts were found for 20 sources including the …
Heavy element abundances in DAO white dwarfs measured from FUSE data
Barstow, M. A.; Holberg, J. B.; Hubeny, I. +3 more
We present heavy element abundance measurements for 16 DAO white dwarfs, determined from Far-Ultraviolet Spectroscopic Explorer (FUSE) spectra. Evidence of absorption by heavy elements was found in the spectra of all the objects. Measurements were made using models that adopted the temperatures, gravities and helium abundances determined from both…
A Virgo high-resolution Hα kinematical survey. I. NGC 4438
Adami, C.; Chemin, L.; Boselli, A. +8 more
New Hα emission-line observations of the Virgo cluster galaxy NGC 4438 are presented. Fabry-Perot interferometry data at an effective angular resolution of ~2 arcsec are used to map the kinematics of the ionized gas in the galaxy. For the first time we obtain a velocity field covering a large area in NGC 4438, much larger than that deduced from pr…
Spatially Resolved Spectral Analysis of Vela Shrapnel D
Katsuda, Satoru; Tsunemi, Hiroshi
The ROSAT all-sky survey discovered several `shrapnels', showing boomerang structures outside the Vela supernova remnant. We observed shrapnel D with the XMM-Newton satellite. There is an X-ray bright ridge structure in our FOV running from north to south. Applying the VNEI model to X-ray spectra of various regions, we find that the plasma in the …