Search Publications
Hubble Space Telescope Images of Magellanic Cloud Planetary Nebulae
Mutchler, Max; Villaver, Eva; Shaw, Richard A. +1 more
We present images and slitless spectra that were obtained in Hubble Space Telescope (HST) surveys of planetary nebulae (PNe) in both the Large and Small Magellanic Clouds, using the Space Telescope Imaging Spectrograph. These new data on 59 PNe (54 in the LMC and 5 in the SMC) permit us to determine the nebular dimensions and morphology in the mon…
Quasar Spectrum Classification with Principal Component Analysis (PCA): Emission Lines in the Lyα Forest
Suzuki, Nao
We investigate the variety in quasar UV spectra (λλ1020-1600), with emphasis on the weak emission lines in the Lyα forest region, using principal component analysis (PCA). We use 50 smooth continuum-fitted quasar spectra (0.14<z<1.04) taken by the Hubble Space Telescope (HST) Faint Object Spectrograph. The first, second, and third principal …
Simultaneous Ultraviolet and X-Ray Observations of the Seyfert Galaxy NGC 4151. II. Physical Conditions in the UV Absorbers
Gull, T. R.; Kriss, G. A.; Turner, T. J. +8 more
We present a detailed analysis, including photoionization modeling, of the intrinsic absorption in the Seyfert 1 galaxy NGC 4151 using ultraviolet (UV) spectra from the Hubble Space Telescope Space Telescope Imaging Spectrograph and the Far Ultraviolet Spectrographic Explorer obtained 2002 May as part of a set of contemporaneous observations that …
Optical Counterparts of Ultraluminous X-Ray Sources Identified from Archival HST WFPC2 Images
van der Marel, Roeland P.; Colbert, Ed; Ptak, Andrew +3 more
We present a systematic analysis of archival HST WFPC2 ``Association'' data sets that correlate with the Chandra positions of a set of 44 ultraluminous X-ray sources (ULXs) of nearby galaxies. The main motivation is to address the nature of ULXs by searching for optical counterparts. Sixteen of the ULXs are found in early-type galaxies (RC3 Hubble…
Low-Redshift Intergalactic Absorption Lines in the Spectrum of HE 0226-4110
Savage, B. D.; Wakker, B. P.; Sembach, K. R. +2 more
We present an analysis of the FUSE and HST STIS E140M spectra of HE 0226-4110 (z=0.495). We detect 56 Lyman absorbers and five O VI absorbers. The number of intervening O VI systems per unit redshift with Wλ>~50 mÅ is dN(O VI)/dz~11. The O VI systems unambiguously trace hot gas only in one case. For the four other O VI systems, photo…
Multiwavelength Star Formation Indicators: Observations
Giavalisco, M.; Leitherer, C.; Armus, L. +5 more
We present a compilation of multiwavelength data on different star formation indicators for a sample of nearby star forming galaxies. Here we discuss the observations, reductions and measurements of ultraviolet images obtained with STIS on board the Hubble Space Telescope (HST), ground-based Hα, and VLA 8.46 GHz radio images. These observations ar…
Unconstrained Astrometric Orbits for Hipparcos Stars with Stochastic Solutions
Makarov, V. V.; Goldin, A.
A considerable number of astrometric binaries whose positions on the sky do not obey the standard model of mean position, parallax, and linear proper motion were observed by the Hipparcos satellite. Some of them remain undiscovered, and their observational data have not been properly processed with the more adequate astrometric model that includes…
The Secondaries of Solar-Type Primaries. I. The Radial Velocities
Abt, Helmut A.; Willmarth, Daryl
We studied for duplicity the 167 F7-G8 IV or V primaries within 25 pc of the Sun according to their Hipparcos parallaxes and between declinations of -30° and +75°. We obtained an average of 13 coudé radial velocities with an accuracy of +/-0.10 km s-1. Combining these measures with published data, we obtained 39 single-lined and 12 doub…
The Star-forming Region NGC 346 in the Small Magellanic Cloud with Hubble Space Telescope ACS Observations. I. Photometry
Henning, Th.; Gouliermis, D. A.; Dolphin, A. E. +1 more
We present a photometric study of the star-forming region NGC 346 and its surrounding field in the Small Magellanic Cloud, using data taken with the Advanced Camera for Surveys (ACS) on board the Hubble Space Telescope (HST). The data set contains both short and long exposures for increased dynamic range, and photometry was performed using the ACS…
The DEEP Groth Strip Survey. VI. Spectroscopic, Variability, and X-Ray Detection of Active Galactic Nuclei
Kobulnicky, Henry A.; Gebhardt, Karl; Willmer, Christopher N. A. +8 more
We identify active galactic nuclei (AGNs) in the Groth-Westphal Survey Strip (GSS) using the independent and complementary selection techniques of optical spectroscopy and photometric variability. We discuss the X-ray properties of these AGNs using Chandra/XMM-Newton data for this region. From a sample of 576 galaxies with high-quality spectra we …