Search Publications
Correlation between halo coronal mass ejections and solar surface activity
Wang, Jingxiu; Zhou, Guiping; Cao, Zhuoliang
We survey all the coronal mass ejections (CMEs) observed by the Large Angle and Spectrometric Coronagraph Experiment (LASCO) aboard the Solar Heliospheric Observatory (SOHO) in the interval from 1997 to 2001, and select 197 frontside halo CMEs whose associated near-surface activity could be clearly identified from SOHO EUV Imaging Telescope (EIT) …
The Puzzling Dynamical Status of the Core of the Globular Cluster NGC 6752
Sabbi, E.; Possenti, A.; Origlia, L. +4 more
We have used high-resolution Hubble Space Telescope Wide Field Planetary Camera 2 and ground-based wide-field images to determine the center of gravity and construct an extended radial density and brightness profile of the cluster NGC 6752 including, for the first time, detailed star counts in the very inner region. The barycenter of the nine inne…
The First Deep Advanced Camera for Surveys Lyα Images of Local Starburst Galaxies
Östlin, Göran; Leitherer, Claus; Mas-Hesse, J. Miguel +2 more
We report the first results from a deep Lyα imaging program of local starburst galaxies with the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope. The two observed galaxies ESO 350-IG038 and SBS 0335-052 have luminosities similar to those of the Magellanic Clouds but differ in their chemical composition. ESO 350-IG038 has an oxygen …
XMM-Newton and Chandra Observations of the Galaxy Group NGC 5044. I. Evidence for Limited Multiphase Hot Gas
Buote, David A.; Brighenti, Fabrizio; Mathews, William G. +1 more
Using new XMM and Chandra observations, we present an analysis of the temperature structure of the hot gas within a radius of 100 kpc of the bright nearby galaxy group NGC 5044. A spectral deprojection analysis of data extracted from circular annuli reveals that a two-temperature model (2T) of the hot gas is favored over single-phase or cooling fl…
A Hubble Space Telescope Wide Field Planetary Camera 2 Survey for Brown Dwarf Binaries in the α Persei and Pleiades Open Clusters
Bouy, Hervé; Barrado y Navascués, David; Martín, Eduardo L. +2 more
We present the results of a high-resolution imaging survey for brown dwarf binaries in two open clusters. The observations were carried out with the Wide Field Planetary Camera 2 on board the Hubble Space Telescope. Our sample consists of eight brown dwarf candidates in α Persei and 25 brown dwarf candidates in the Pleiades. We have resolved four …
Age Dependence of the Vega Phenomenon: Observations
Waters, L. B. F. M.; Dominik, C.; Waelkens, C. +1 more
We study the time dependency of Vega-like excesses using infrared studies obtained with the imaging photopolarimeter ISOPHOT on board the Infrared Space Observatory. We review the different studies published on this issue and critically check and revise ages and fractional luminosities in the different samples. The conclusions of our study differ …
The spiral galaxy M 33 mapped in the FIR by ISOPHOT. A spatially resolved study of the warm and cold dust
Lemke, D.; Völk, H. J.; Klaas, U. +4 more
The Sc galaxy M 33 has been mapped with ISOPHOT in the far-infrared, at 60, 100, and 170 mu m. The spatial resolution of these FIR maps allows the separation of spiral arms and interarm regions and the isolation of a large number of star-forming regions. The spectral energy distribution in the FIR indicates a superposition of two components, a war…
The Structure of Stellar Coronae in Active Binary Systems
Sanz-Forcada, J.; Dupree, A. K.; Brickhouse, N. S.
A survey of 28 stars (22 active binary systems, plus six single stars or wide binaries for comparison) using extreme ultraviolet spectra has been conducted to establish the structure of stellar coronae in active binary systems from the emission measure distribution (EMD), electron densities, and scale sizes. Observations obtained by the Extreme Ul…
Chandra Observations of QSO 2237+0305
Agol, E.; Garmire, G. P.; Bautz, M. W. +2 more
We present the observations of the gravitationally lensed system QSO 2237+0305 (Einstein Cross) performed with the Advanced CCD Imaging Spectrometer on board the Chandra X-Ray Observatory on 2000 September 6 and on 2001 December 8 for 30.3 and 9.5 ks, respectively. Imaging analysis resolves the four X-ray images of the Einstein Cross. A possible f…
The Baldwin Effect and Black Hole Accretion: A Spectral Principal Component Analysis of a Complete Quasar Sample
Laor, Ari; Wills, D.; Shang, Zhaohui +4 more
We have performed a spectral principal component analysis (SPCA) for an essentially complete sample of 22 low-redshift QSOs with spectral data from Lyα to Hα. SPCA yields a set of independent principal component spectra, each of which represents a set of relationships among QSO continuum and line properties. We find three significant principal com…