Search Publications
Hubble Space Telescope Measurements of the Expansion of NGC 6543: Parallax Distance and Nebular Evolution
Casertano, Stefano; Panagia, Nino; Balick, Bruce +5 more
The optical expansion parallax of NGC 6543 has been detected and measured using two epochs of Hubble Space Telescope images separated by a time baseline of only 3 years. We have utilized three separate methods of deriving the angular expansion of bright fiducials, with excellent agreement in the results. We combine our angular expansion estimates …
An Unusual Brightening Of Eta Carinae
Gull, Theodore R.; Humphreys, Roberta M.; Davidson, Kris +7 more
HST/Space Telescope Imaging Spectrograph data show that the apparent near-UV, visual-wavelength, and near-IR brightness of η Car increased by a factor of two during 1998. Meanwhile its Homunculus ejecta nebula brightened by about 30%, the largest fluctuation of this type in the past 40 years. These developments were quite unexpected and are not ea…
The Deuterium Abundance at z=0.701Z = 0.701 toward QSO 1718+4807
Savage, Blair D.; Lu, Limin; Burles, Scott +3 more
We present constraints on the deuterium-to-hydrogen ratio (D/H) in the metal-poor gas cloud at redshift z=0.701 toward QSO 1718+4807. We use new Keck spectra in addition to Hubble Space Telescope (HST) and International Ultraviolet Explorer spectra. We use an improved redshift and a lower H I column density to model the absorption. The HST spectru…
The Environments of Supernovae in Post-Refurbishment Hubble Space Telescope Images
Van Dyk, Schuyler D.; Filippenko, Alexei V.; Barth, Aaron J. +1 more
The locations of supernovae (SNe) in the local stellar and gaseous environment in galaxies contain important clues to their progenitor stars. Access to this information, however, has been hampered by the limited resolution achieved by ground-based observations. High spatial resolution Hubble Space Telescope (HST) images of galaxy fields in which s…
The Etched Hourglass Nebula MyCn 18. I. Hubble Space Telescope Observations
Ballester, Gilda E.; Crisp, David; Holtzman, Jon A. +15 more
We have obtained emission-line and continuum images of the young planetary nebula MyCn 18 with the Wide Field Planetary Camera 2 on the Hubble Space Telescope (HST). Although from the ground MyCn 18 appeared to have a triple-ring structure similar to SN 1987A, the HST images show that MyCn 18 has an overall hourglass shape. A series of arcs appear…
NICMOS and VLA Observations of the Gravitationally Lensed Ultraluminous BAL Quasar APM 08279+5255: Detection of a Third Image
Lewis, Geraint F.; Ibata, Rodrigo A.; Irwin, Michael J. +2 more
We present a suite of observations of the recently identified ultraluminous BAL quasar APM 08279+5255, taken both in the infrared with the NICMOS high-resolution camera on board the Hubble Space Telescope and at 3.5 cm with the Very Large Array. With an inferred luminosity of ~5x1015 Lsolar, APM 08279+5255 is apparently the m…
Distance to the Cygnus Loop from Hubble Space Telescope Imaging of the Primary Shock Front
Blair, William P.; Raymond, John C.; Long, Knox S. +1 more
We present a Hubble Space Telescope (HST) Wide Field Planetary Camera 2 narrowband Hα image of a region on the northeastern limb of the Cygnus Loop supernova remnant. This location provides a detailed example of where the primary blast wave first encounters the surrounding interstellar medium. The filament structure is seen in exquisite detail in …
HST/FOS Spatially Resolved Spectral Classification of Compact OB Groups in the Large Magellanic Cloud
Walborn, Nolan R.; Parker, Joel Wm.; White, Richard L. +3 more
Blue-violet spectrograms of individual components in four compact OB groups of the Large Magellanic Cloud, obtained with the Hubble Space Telescope (HST) Faint Object Spectrograph (FOS), are presented and discussed. Two of the massive multiple systems are in the 30 Doradus periphery, while the other two represent the core and the peripheral, trigg…
Late-Time Optical and Ultraviolet Spectra of SN 1979C and SN 1980K
Filippenko, Alexei V.; Fransson, Claes; Chevalier, Roger A. +8 more
A low-dispersion Keck I spectrum of SN 1980K taken in 1995 August (t=14.8 yr after explosion) and a spectrum taken in 1997 November (t=17.0 yr) at the MDM Observatory show broad 5500 km s^-1 emission lines of Hα, [O I] 6300, 6364 Å, and [O II] 7319, 7330 Å. Weaker but similarly broad lines detected include [Fe II] 7155 Å, [S II] 4068, 4072 Å, and …
Mapping Low-Density Intergalactic Gas: A Third Helium LYalpha Forest
Williams, Benjamin F.; Anderson, Scott F.; Hogan, Craig J. +1 more
We present a new HST/STIS spectrum of the z=3.18 quasar PKS 1935-692 and summarize the spectral features shortward of 304 Å in the rest frame likely to be caused by foreground He II Lyalpha absorption. In accord with the previous results on two other quasars at similar redshifts, we demonstrate a correlation with the H I Lyalpha forest absorption …