The Circumstellar Medium of Cassiopeia A Inferred from the Outer Ejecta Knot Properties (2009)
We investigate the effect of the circumstellar medium density profile on the X-ray emission from outer ejecta knots in the Cassiopeia A supernova remnant using the 1 Ms Chandra observation. The...
Katsuda, Satoru, Petre, Robert, Hwang, Una, Yamaguchi, Hiroya, Mori, Koji, Tsunemi, Hiroshi
We present results from X-ray analysis of a Galactic middle-aged supernova remnant (SNR) G156.2+5.7 which is bright and largely extended in X-ray wavelengths, showing a clear circular shape (radius...
X-ray Emitting Ejecta in Puppis A Observed with Suzaku (2007)
Hwang, Una, Petre, Robert, Flanagan, Kathryn A.
We report the detection and localization of X-ray emitting ejecta in the middle-aged Galactic supernova remnant Puppis A using five observations with the Suzaku X-ray Imaging Spectrometer to survey...
The X-ray observatory Suzaku (2007)
Mitsuda, Kazuhisa, Bautz, Mark, Inoue, Hajime, Kelley, Richard L., Koyama, Katsuji, Kunieda, Hideyo, ...
The Cassiopeia A Supernova Remnant in X-Rays (2007)
We review progress to date on analysis of the 1 million second Chandra Very Large Project (VLP)observation of the Cassiopeia A supernova remnant. We explore the possibility that Cas A exploded into a...
The Polar Regions of Cassiopeia A: The Aftermath of a Gamma Ray Burst? (2006)
Laming, J. Martin, Hwang, Una, Radics, Balint, Lekli, Gergely, Takacs, Endre
Probably not, but it is interesting nevertheless to investigate just how close Cas A might have come to generating such an event. Focusing on the northeast jet filaments, we analyze the polar regions...
Badenes, Carles, Borkowski, Kazimierz J., Hughes, John P., Hwang, Una, Bravo, Eduardo
In this paper we use high quality X-ray observations from XMM-Newton and Chandra to gain new insights into the explosion that originated Tycho's supernova 433 years ago. We perform a detailed...
Hwang, Una, Flanagan, Kathryn A., Petre, Robert
We present Chandra X-ray images and spectra of the most prominent cloud-shock interaction region in the Puppis A supernova remnant. The Bright Eastern Knot (BEK) has two main morphological...
Una Hwang, J. Martin Laming, Carles Badenes, Fred Berendse, John Blondin, Denis Cioffi, ...
We introduce a million-second observation of the supernova remnant Cassiopeia A with the Chandra X-ray Observatory. The bipolar structure of the Si-rich ejecta (NE jet and SW counterpart) is clearly...
A Million-Second Chandra View of Cassiopeia A (2004)
Hwang, Una, Laming, J. Martin, Badenes, Carles, Berendse, Fred, Blondin, John, Cioffi, Denis, ...
We introduce a million-second observation of the supernova remnant Cassiopeia A with the Chandra X-ray Observatory. The bipolar structure of the Si-rich ejecta (NE jet and SW counterpart) is clearly...
Where was the Iron Synthesized in Cassiopeia A? (2003)
We investigate the properties of Fe-rich knots on the east limb of the Cassiopeia A supernova remnant using observations with Chandra/ACIS and analysis methods developed in a companion paper. We use...
We present a detailed analysis of Chandra X-ray spectra from individual ejecta knots in the supernova remnant Cassiopeia A. The spectra are fitted to give the electron temperature and (single)...
Thermal and Nonthermal Emission from the Forward Shock in Tycho's Supernova Remnant (2002)
Hwang, Una, Decourchelle, Anne, Holt, Stephen S., Petre, Robert
We present Chandra X-ray images of Tycho's supernova remnant that delineate its outer shock as a thin, smooth rim along the straight northeastern edge and most of the circular western half. The...
X-ray spectrum of supernova remnant 1987A (2002)
Michael, Eli, Zhekov, Svetozar, McCray, Richard, Hwang, Una, Burrows, David N., Park, Sangwook, ...
We discuss the X-ray emission observed from supernova remnant 1987A with the Chandra X-Ray Observatory. We analyze a high- resolution spectrum obtained in 1999 October with the high- energy...
The X-ray Spectrum of Supernova Remnant 1987A (2001)
Michael, Eli, Zhekov, Svetozar, McCray, Richard, Hwang, Una, Burrows, David N., Park, Sangwook, ...
We discuss the X-ray emission observed from Supernova Remnant 1987A with the Chandra X-ray Observatory. We analyze a high resolution spectrum obtained in 1999 October with the high energy...
Is the Compact Source at the Center of Cas A Pulsed? (2001)
Murray, Stephen S., Ransom, Scott M., Juda, Michael, Hwang, Una, Holt, Stephen S.
A 50 ksec observation of the Supernova Remnant Cas A was taken using the Chandra X-Ray Observatory High Resolution Camera (HRC) to search for periodic signals from the compact source located near the...
The Thermal X-ray Emitting Shell of LMC Supernova Remnant 0540-693 (2001)
Hwang, Una, Petre, Robert, Holt, Stephen S., Szymkowiak, Andrew E.
We use data from the Advanced CCD Imaging Spectrometer (ACIS) on the Chandra X-ray Observatory to image the shell surrounding the pulsar B0540-69, and to measure its spectral properties. Weak...
X-ray Observations of Young Supernova Remnants (2001)
This brief review of recent X-ray observations of young supernova remnants highlights results obtained by the Chandra and XMM Newton Observatories since their launch last year. Their impressive...
The X-ray Remnant of SN1987A (2000)
Burrows, David N., Michael, Eli, Hwang, Una, McCray, Richard, Chevalier, Roger A., Petre, Robert, ...
We present high resolution Chandra observations of the remnant of SN1987A in the Large Magellanic Cloud. The high angular resolution of the Chandra X-ray Observatory (CXO) permits us to resolve the...
Mapping the X-ray Emitting Ejecta in Cassiopeia A with Chandra (2000)
Hwang, Una, Holt, Stephen S., Petre, Robert
We present X-ray emission line equivalent width images of the bright Galactic supernova remnant Cassiopeia A for the elements Si, S, Ar, Ca, and Fe using a 50,000 s observation with the Advanced CCD...
The X-ray Line Emission from the Supernova Remnant W49B (1999)
Hwang, Una, Petre, Robert, Hughes, John P.
The Galactic supernova remnant W49B has one of the most impressive X-ray emission line spectra obtained with the Advanced Satellite for Cosmology and Astronomy (ASCA). We use both plasma line...
Mass and Metallicity of Five X-ray Bright Galaxy Groups (1998)
Hwang, Una, Mushotzky, Richard F., Burns, Jack O., Fukazawa, Yasushi, White, Richard A., ...
We present ASCA X-ray observations of a sample of five groups selected from a cross-correlation of the ROSAT All-Sky Survey with the White et al. optical catalog of groups. These X-ray bright groups...
The X-ray Iron Emission from Tycho's Supernova Remnant (1997)
Hwang, Una, Hughes, John P., Petre, Robert
We present the results of broadband fits to the X-ray spectrum of Tycho's supernova remnant obtained by the Solid-State Imaging Spectrometers on the ASCA Observatory. We use single-temperature,...
X-Ray Emission Line Imaging and Spectroscopy of Tycho's Supernova Remnant (1996)
We present X-ray images of Tycho's supernova remnant in emission line features of Mg, Si, S, Ar, Ca, and Fe, plus the continuum, using data obtained by the imaging spectrometers onboard the ASCA...
X-rays from Superbubbles in the Large Magellanic Cloud IV: The Blowout Structure of N44 (1996)
Magnier, Eugene A., Chu, You-Hua, Points, Sean D., Hwang, Una, Smith, R. Chris
We have used optical echelle spectra along with ROSAT and ASCA X-ray spectra to test the hypothesis that the southern portion of the N44 X-ray bright region is the result of a blowout structure....
X-ray studies of supernova remnants (1994)
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 1994.
X-ray studies of supernova remnants /--by Una Hwang. (1994)
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 1994.
X-ray studies of supernova remnants (1994)
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 1994.