Search Publications
Infrared Space Observatory Observations of Molecular Hydrogen in HH 54:Measurement of a Nonequilibrium Ratio of Ortho- to Para-H2
Neufeld, David A.; Melnick, Gary J.; Harwit, Martin
We have detected the S(1), S(2), S(3), S(4), and S(5) pure rotational lines of molecular hydrogen toward the outflow source HH 54 using the Short Wavelength Spectrometer on board the Infrared Space Observatory. The observed H2 line ratios indicate the presence of warm molecular gas with an H2 density of at least 105
Hot White Dwarfs in the Extreme-Ultraviolet Explorer Survey. IV. DA White Dwarfs with Bright Companions
Vennes, Stéphane; Thorstensen, John R.; Christian, Damian J.
We present an analysis of optical, ultraviolet, and X-ray spectral properties of a sample of 13 hot hydrogen-rich (DA) white dwarfs, each paired with a luminous unresolved companion. Using low-dispersion International Ultraviolet Explorer spectra, ROSAT photometry, and Extreme-Ultraviolet Explorer photometry and spectroscopy, we estimate the effec…
Asymmetry and Frequencies of Low-Degree p-Modes and the Structure of the Sun's Core
Kosovichev, A. G.; Scherrer, P. H.; Appourchaux, T. +3 more
An accurate determination of the frequencies of low-degree solar p-modes is an important task of helioseismology. Using 679 days of solar oscillation data observed in Doppler velocity and continuum intensity from two Solar and Heliospheric Observatory instruments (the Michelson Doppler Imager and the SunPhotoMeter), we show that fitting the spectr…
On the Association of Gamma-Ray Bursts with Supernovae
Galama, T. J.; Hurley, K.; Kouveliotou, C. +7 more
The recent discovery of a supernova (SN 1998bw) seemingly associated with GRB 980425 adds a new twist to the decades-old debate over the origin of gamma-ray bursts. To investigate the possibility that some (or all) bursts are associated with supernovae, we performed a systematic search for temporal/angular correlations using catalogs of BATSE and …
High-Resolution Near-Infrared Imaging of the Orion 114-426 Silhouette Disk
Schneider, Glenn; Rieke, Marcia; Bally, John +6 more
We present the first high-resolution near-infrared images of the edge-on silhouette circumstellar disk, Orion 114-426, made using NICMOS on the Hubble Space Telescope. Images taken against the bright nebular background of the ionized hydrogen Paα line at 1.87 µm show the major axis of the disk to be approximately 20% smaller than at 0.6 &mic…
The Coronae of Moderate-Mass Giants in the Hertzsprung Gap and the Clump
Ayres, Thomas R.; Brown, Alexander; Wood, Brian E. +3 more
We have used the Röentgensatellit (ROSAT), the Extreme Ultraviolet Explorer (EUVE), and the Hubble Space Telescope (HST) to measure X-ray and ultraviolet emissions of moderate-mass (~2-3 M⊙) giants in the Hertzsprung gap (spectral types early F to mid-G) and the post-helium flash ``clump'' (~G8-K0). Our motivation was to document the ev…
Ejected Nebulae as Probes of the Evolution of Massive Stars in the Large Magellanic Cloud
Smith, Linda J.; Leitherer, Claus; Clampin, Mark +3 more
We present new Hubble Space Telescope (HST) Faint Object Spectrograph (FOS) and ground-based long-slit spectroscopic observations of the nebulae around the two LMC luminous blue variables (LBVs) R127 (=HDE 269858) and R143 (=HDE 269929) and the Ofpe/WN9 star S119 (=HDE 269687). We have used the ground-based long-slit spectra to investigate the kin…
New Constraints on the Luminosity Evolution of Spheroidal Galaxies in Distant Clusters
Smail, I.; Poggianti, B. M.; Aragón-Salamanca, A. +6 more
We investigate various probes of luminosity evolution in the rich cluster environment, concentrating in particular on the spheroidal (E/S0) galaxies, using a newly constructed catalog of morphologically classified Hubble Space Telescope (HST) images of galaxies observed in the cores of 13 clusters with redshifts 0.17 <= z <= 0.56. An importa…
The Extragalactic Distance Scale Key Project. V. Photometry of the Brightest Stars in M100 and the Calibration of WFPC2
Illingworth, Garth D.; Madore, Barry F.; Freedman, Wendy L. +18 more
We present multiepoch VI observations of the brightest stars in the Virgo spiral galaxy M100 obtained with the WFPC2 aboard the Hubble Space Telescope. Particular attention has been given to the WFPC2 calibration process, and a new calibration is presented here. We find that a calibration based on short exposure (t <= 60 sec) observations of th…
First Measurement of the Submillimeter Sunyaev-Zeldovich Effect
Bock, J. J.; Giard, M.; Pajot, F. +10 more
We report the first detection of the Sunyaev-Zeldovich (S-Z) increment on the cosmic microwave background at submillimeter wavelengths in the direction of a cluster of galaxies. It was achieved toward the rich cluster Abell 2163, using the PRONAOS 2 m stratospheric telescope. Together with data from the SuZIE, Diabolo, and ISO-PHT experiments, the…