Search Publications
Quantitative analysis of WC stars: constraints on neon abundances from ISO-SWS spectroscopy
Hillier, D. John; Morris, Patrick W.; Crowther, Paul A. +3 more
Neon abundances are derived in four Galactic WC stars - γ2Vel (WR11, WC8+O7.5III), HD156385 (WR90, WC7), HD192103 (WR135, WC8) and WR146 (WC5+O8) - using mid-infrared fine-structure lines obtained with ISO-SWS. Stellar parameters for each star are derived using the non-local thermodynamic equilibrium model atmospheric code of Hillier &a…
The Hubble Deep Field South: Formulation of the Observing Campaign
Ferguson, Henry C.; Lucas, Ray A.; Brown, Thomas M. +51 more
Deep, multiband observations of high Galactic latitude fields are an essential tool for studying topics ranging from Galactic structure to extragalactic background radiation. The Hubble Deep Field (HDF-N) observations obtained in 1995 December established a standard for such narrow, deep surveys. The field has been extensively analyzed by a variet…
Seismic Images of the Far Side of the Sun
Braun, D. C.; Lindsey, C.
Images of an active region on the far side of the sun were derived by applying seismic holography to recent helioseismic observations from space. Active regions are the centers of energetic phenomena such as solar flares and coronal mass ejections, whose resulting electromagnetic and particle radiation interfere with telecommunications and power t…
Hubble Space Telescope Observations of Vibrationally Excited Molecular Hydrogen in Cluster Cooling Flow Nebulae
Mack, Jennifer; Donahue, Megan; Voit, G. Mark +3 more
We report the results of Hubble Space Telescope near-infrared camera and multiobject spectrometer and Wide Field Planetary Camera 2 imaging of emission-line nebulae in the central galaxies of three clusters of galaxies purported to host massive cooling flows: Perseus (NGC 1275), Abell 2597, and PKS 0745-191. The spectral signature of vibrationally…
WFPC2 Images of a Face-on Disk Surrounding TW Hydrae
Ménard, François; Krist, John E.; Stapelfeldt, Karl R. +2 more
Hubble Space Telescope observations of the isolated T Tauri star TW Hydrae reveal the presence of a compact circumstellar nebula. After subtraction of a reference point-spread function (PSF), a smooth, symmetrical, circular halo can be seen in both R- and I-band WFPC2 images. Its intensity declines with radius until reaching an outer sensitivity l…
Preliminary Spectral Analysis of the Type II Supernova 1999EM
Filippenko, Alexei V.; Kirshner, R. P.; McCray, R. +19 more
We have calculated fast direct spectral model fits to two early-time spectra of the Type II plateau SN 1999em, using the SYNOW synthetic spectrum code. The first is an extremely early blue optical spectrum and the second a combined Hubble Space Telescope and optical spectrum obtained one week later. Spectroscopically this supernova appears to be a…
High-Resolution Optical/Near-Infrared Imaging of Cool Ultraluminous Infrared Galaxies
Sanders, D. B.; Evans, A. S.; Surace, Jason A.
We present high spatial resolution (FWHM~0.3"-0.8") BIHK'-band imaging of a sample of ultraluminous infrared galaxies (Lir>1012 Lsolar ULIGs) with ``cool'' mid-infrared colors (f25µm/f60µm<0.2), which select against active galactic nucleus-like (AGN-like) systems, …
The X-Ray Transient XTE J1118+480: Multiwavelength Observations of a Low-State Minioutburst
Chaty, S.; Cui, W.; Shrader, C. R. +3 more
We present multiwavelength observations of the newly discovered X-ray transient XTE J1118+480 obtained in the rising phase of the 2000 April outburst. This source is located at unusually high Galactic latitude and in a very low absorption line of sight. This made the first Extreme Ultraviolet Explorer (EUVE) spectroscopy of an X-ray transient outb…
Saturn's Zonal Winds at Cloud Level
Sada, Pedro V.; Sanchez-Lavega, Agustín.; Rojas, José F.
We present an analysis of new cloud motion measurements in Saturn's atmosphere from Voyager 1 and 2 images and define a nominal zonal wind velocity vs latitude profile for the cloud top level that can be used as reference for the upcoming Cassini mission. Improvements over previous studies include: (i) twice the number of wind vectors used, (ii) i…
The Ultraviolet and Optical Spectra of Metal-deficient O Stars in the Small Magellanic Cloud
Walborn, Nolan R.; Parker, Joel Wm.; Smith, Linda J. +4 more
An ultraviolet and optical spectral atlas of 15 O stars in the Small Magellanic Cloud (SMC) is presented and described. The echelle data have resolving powers of order 104; they were obtained with the Hubble Space Telescope Space Telescope Imaging Spectrograph in the UV, and at the Anglo-Australian Telescope or the European Southern Obs…