Search Publications
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…
Effect of the H I Lyα Chromospheric Flux Anisotropy on the Total Intensity of the Resonantly Scattered Coronal Radiation
Auchère, F.
In modeling of the resonantly scattered solar coronal Lyα line of H I, the intensity of the chromospheric source is often assumed to be uniform. We investigate the validity of this assumption. After establishing a correlation between the H I 121.6 nm and He II 30.4 nm line intensities, we build Carrington maps of the Lyα chromosphere from SOHO EUV…
Deconstructing NGC 7130
Heckman, T. M.; Levenson, N. A.; Weaver, K. A. +2 more
Observations of the Seyfert 2 and starburst galaxy NGC 7130 with the Chandra X-Ray Observatory illustrate that both of these phenomena contribute significantly to the galaxy's detectable X-ray emission. The active galactic nucleus (AGN) is strongly obscured, buried beneath column density NH>1024cm-2, and it is m…
Far Ultraviolet Spectroscopic Explorer Measurements of Interstellar Fluorine
Federman, S. R.; Lambert, David L.; Smith, V. V. +1 more
The source of fluorine is not well understood, although core-collapse supernovae, Wolf-Rayet stars, and asymptotic giant branch stars have been suggested. A search for evidence of the ν-process during Type II supernovae is presented. Absorption from interstellar F I is seen in spectra of HD 208440 and HD 209339A acquired with the Far Ultraviolet S…
On the Afterglow and Host Galaxy of GRB 021004: A Comprehensive Study with the Hubble Space Telescope
Pian, E.; Kouveliotou, C.; Tanvir, N. +24 more
We report on Hubble Space Telescope (HST) observations of the late-time afterglow and host galaxy of GRB 021004 (z=2.33). Although this gamma-ray burst (GRB) is one of the best observed so far in terms of sampling in the time domain, multiwavelength coverage, and polarimetric observations, there is substantial disagreement between different interp…