Search Publications
Properties of Resolved Star Clusters in M51
Whitmore, Bradley C.; Chandar, Rupali; Lee, Myung Gyoon
We present a study of compact star clusters in the nearby pair of interacting galaxies NGC 5194/5195 (M51), based on multifilter Hubble Space Telescope (HST) WFPC2 archival images. We have detected ~400 isolated, resolved clusters in five HST WFPC2 fields of the two-galaxy system. Due to our requirement that the clusters be detected based only on …
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…
Batch discovery of nine z~ 1 clusters using X-ray and K or R, z' images
Altieri, B.; Valtchanov, I.; Pierre, M. +5 more
We present the results of an initial search for clusters of galaxies at z~ 1 and above, using data from 2.9 square degrees of XMM-Newton images. By selecting weak potentially extended X-ray sources with faint or no identifications in deep, ground-based optical imaging, we have constructed a starting sample of 19 high-redshift cluster candidates. N…
On metal-deficient barium stars and their link with yellow symbiotic stars
Jorissen, A.; Udry, S.; Musaev, F. A. +2 more
This paper addresses the question of why metal-deficient barium stars are not yellow symbiotic stars (YSyS). Samples of (suspected) metal-deficient barium (mdBa) stars and YSyS have been collected from the literature, and their properties reviewed. It appears in particular that the barium nature of the suspected mdBa stars needs to be ascertained …
The Saturnian plasma sheet as revealed by energetic particle measurements
Livi, S.; Krupp, N.; Woch, J. +9 more
Since July 2004 Cassini is in orbit around Saturn providing in-situ measurements of the Saturnian magnetosphere. One of the three sensors of the Magnetospheric Imaging Instrument (MIMI) is the Low Energy Magnetospheric Measurement System (LEMMS) that responds to energetic particles which can serve as indicators of key regions (Krimigis et al., 200…
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…