Search Publications
The Nature of Associated Absorption and the Ultraviolet-X-Ray Connection in 3C 288.1
Shields, Joseph C.; Netzer, Hagai; Hamann, Frederick W.
We discuss new Hubble Space Telescope spectroscopy of the radio-loud quasar 3C 288.1. The data cover ~590 to ~1610 Å in the quasar rest frame. They reveal a wealth of associated absorption lines (AALs) with no accompanying Lyman-limit absorption. The metallic AALs range in ionization from C III and N III to Ne VIII and Mg X. We use these data and …
The Globular Cluster Systems in the Coma Ellipticals. II. Metallicity Distribution and Radial Structure in NGC 4874 and Implications for Galaxy Formation
Kavelaars, J. J.; Harris, William E.; Hesser, James E. +2 more
Deep Hubble Space Telescope WFPC2 images in V and I are used to investigate the globular cluster system (GCS) in NGC 4874, the central cD galaxy of the Coma cluster. Although the luminosity function of the clusters displays its normal Gaussian-like shape and turnover level, other features of the system are surprising. We find the GCS to be (a) spa…
The Temperature and Cooling Age of the White Dwarf Companion to the Millisecond Pulsar PSR B1855+09
Kulkarni, S. R.; van Kerkwijk, M. H.; Kaspi, V. M. +1 more
We report on Keck and Hubble Space Telescope observations of the binary millisecond pulsar PSR B1855+09. We detect its white dwarf companion and measure mF555W=25.90+/-0.12 and mF814W=24.19+/-0.11 (Vega system). From the reddening-corrected color, (mF555W-mF814W)0=1.06+/-0.21, we infer a tempe…
Hubble Space Telescope Imaging Spectrograph Observations of the Hot White Dwarf in the Close Binary Feige 24
Vennes, Stéphane; Thorstensen, John R.; Polomski, Elisha F. +3 more
We obtained and analyzed two Hubble Space Telescope Imaging Spectrograph spectra of the white dwarf in the DA plus dMe binary Feige 24. The spectra, obtained at orbital quadratures, provide new estimates of the white dwarf motion and gravitational redshift resulting in revised white dwarf parameters. An analysis of interstellar absorption lines re…
Diffraction-limited Near-IR Imaging at Keck Reveals Asymmetric, Time-variable Nebula around Carbon Star CIT 6
Tuthill, P. G.; Monnier, J. D.; Danchi, W. C.
We present multiepoch, diffraction-limited images of the nebula around the carbon star CIT 6 at 2.2 and 3.1 µm from aperture masking on the Keck I Telescope. The near-IR nebula is resolved into two main components, an elongated, bright feature showing time-variable asymmetry and a fainter component about 60 mas away with a cooler color tempe…
Large Magellanic Cloud Planetary Nebula Morphology: Probing Stellar Populations and Evolution
Blades, J. Chris; Balick, Bruce; Shaw, Richard A. +1 more
Planetary nebulae (PNe) in the Large Magellanic Cloud (LMC) offer the unique opportunity to study both the population and evolution of low- and intermediate-mass stars, by means of the morphological type of the nebula. Using observations from our LMC PN morphological survey, and including images available in the Hubble Space Telescope Data Archive…
Nuclear Bar, Star Formation, and Gas Fueling in the Active Galaxy NGC 4303
Colina, Luis; Wada, Keiichi
A combination of Hubble Space Telescope Wide Field Planetary Camera 2 (WFPC2) and Near-Infrared Camera Multiobject Spectrograph (NICMOS) images are used to investigate the gas/dust and stellar structure inside the central 300 pc of the nearby active galaxy NGC 4303. The NICMOS H-band (F160W) image reveals a bright core and a nuclear-elongated barl…
Probing Cosmology with the X-Ray Forest
Canizares, Claude R.; Fang, Taotao
There is a growing consensus that in the present universe most baryons reside in galaxy clusters and groups in the form of highly ionized gas at temperatures of 106-108 K. The H-like and He-like ions of the heavy elements can produce absorption features-the so-called ``X-ray forest''-in the X-ray spectrum of a background quas…
Far Ultraviolet Spectroscopic Explorer Spectroscopy of the O VI Resonance Doublet in Sand 2 (WO)
Sonneborn, G.; Hillier, D. J.; Willis, A. J. +9 more
We present Far Ultraviolet Spectroscopic Explorer spectroscopy of Sand 2, an LMC WO-type Wolf-Rayet star, revealing the O VI resonance P Cygni doublet at 1032-1038 Å. These data are combined with Hubble Space Telescope Faint Object Spectrograph ultraviolet and Mount Stromlo 2.3 m optical spectroscopy and analyzed using a spherical, non-LTE, line-b…
Gasdynamics in the LINER Galaxy NGC 5005: Episodic Fueling of a Nuclear Disk
Sakamoto, Kazushi; Baker, Andrew J.; Scoville, Nick Z.
We report high-resolution CO(1-0) observations in the central 6 kpc (1') of the LINER galaxy NGC 5005 with the Owens Valley Radio Observatory millimeter array. Molecular gas is distributed in three components-a ring at a radius of about 3 kpc, a strong central condensation, and a stream to the northwest of the nucleus but inside the 3 kpc ring. Th…