Search Publications
FUSE Determination of a Low Deuterium Abundance along an Extended Sight Line in the Galactic Disk
Moos, H. W.; Chayer, P.; Dupuis, J. +5 more
We present a study of the deuterium abundance along the extended sight line toward HD 90087 with the Far Ultraviolet Spectroscopic Explorer (FUSE). HD 90087 is a O9.5 III star located in the Galactic disk at a distance of ~2.7 kpc away from the Sun. Both in terms of distance and column densities, HD 90087 has the longest and densest sight line obs…
Sculpting a Pre-planetary Nebula with a Precessing Jet: IRAS 16342-3814
Sahai, R.; Sánchez Contreras, C.; Le Mignant, D. +2 more
We have imaged the bipolar pre-planetary nebula IRAS 16342-3814 with the Keck adaptive optics (AO) system in four near-infrared bands in the 1.6-4.7 µm range. The lobes, which showed smoothly varying brightness distributions in previous optical images taken with the Hubble Space Telescope, have a limb-brightened appearance in the AO images, …
Isothermal Bias of the ``Filter Ratio'' Method for Observations of Multithermal Plasma
Schmelz, J. T.; DeLuca, E. E.; Weber, M. A. +1 more
An early result from the Transition Region and Coronal Explorer (TRACE) was that the EUV filter ratios for many narrow coronal loops (widths of a few arcseconds) were found to cluster within the small range 0.50-1.70, as functions of position along loop length. The most common interpretation is that the temperature along the loop is in fact nearly…
Abundances and Depletions of Interstellar Oxygen
Snow, Theodore P.; Rachford, Brian L.; Jensen, Adam G.
We report on the abundance of interstellar neutral oxygen (O I) for 26 sight lines, using data from the Far Ultraviolet Spectroscopic Explorer, the International Spectroscopic Explorer, and the Hubble Space Telescope. O I column densities are derived by measuring the equivalent widths of several ultraviolet absorption lines and subsequently fittin…
Luminosity and Mass Limits for the Progenitor of the Type Ic Supernova 2004gt in NGC 4038
Smartt, Stephen J.; Maund, Justyn R.; Schweizer, Francois
We report on our attempts to locate the progenitor of the Type Ic supernova SN 2004gt in NGC 4038. We use high-resolution HST ACS images of SN 2004gt and have compared them with deep pre-explosion HST WFPC2 F336W, F439W, F555W, and F814W images. We identify the SN location on the pre-explosion frames with an accuracy of 5 mas. We show that the pro…
Radial Distribution of Dust Grains around HR 4796A
Wahhaj, Z.; Lis, D. C.; Koerner, D. W. +4 more
We present high dynamic range images of circumstellar dust around HR 4796A that were obtained with MIRLIN at the Keck II telescope at λ=7.9, 10.3, 12.5, and 24.5 µm. We also present a new continuum measurement at 350 µm obtained at the Caltech Submillimeter Observatory. Emission is resolved in Keck images at 12.5 and 24.5 µm with…
Broadband Metric-Range Radio Emission Associated with a Moreton/EIT Wave
Magdalenić, J.; Temmer, M.; Mann, G. +5 more
We present the evolution and kinematics of a broadband radio source that propagated collaterally with an Hα/EIT wave, linking it with the type II burst that was excited higher up in the corona. The NRH wave emission extended from the frequency f~327 to f<151 MHz and was considerably weaker than the flare-related type IV burst. The emission cent…
Detailed Spectral Analysis of the 260 ks XMM-Newton Data of 1E 1207.4-5209 and Significance of a 2.1 keV Absorption Feature
Hailey, Charles J.; Mori, Kaya; Chonko, James C.
We have reanalyzed the 260 ks XMM-Newton observation of 1E 1207.4-5209. There are several significant improvements over previous work. First, a much broader range of physically plausible spectral models was used. Second, we have used a more rigorous statistical analysis. The standard F-distribution was not employed, but rather the exact finite sta…
Sequential Chromospheric Brightenings beneath a Transequatorial Halo Coronal Mass Ejection
Thompson, B. J.; Balasubramaniam, K. S.; Pevtsov, A. A. +5 more
Analyses of multiwavelength data sets for a solar eruption at ~21:30 UT on 2002 December 19 show evidence for the disappearance of a large-scale, transequatorial coronal loop (TL). In addition, coronal manifestations of the eruption (based on SOHO EIT and LASCO images) include large-scale coronal dimming, flares in each associated active region in…
Interstellar Ca II Line Intensities and the Distances of the OB stars
Galazutdinov, G. A.; Han, Inwoo; Strobel, A. +4 more
We show that the equivalent widths of the well-known interstellar Ca II H and K lines can be used to determine the distances to OB stars in our Galaxy. The equivalent widths, measured in the spectra of 147 early-type stars, are strongly related to the Hipparcos parallaxes of those objects. The lines fitted to the parallax-equivalent width data are…