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XMM-Newton Observations of the Neutron Star X-Ray Transient KS 1731-260 in Quiescence
Guainazzi, Matteo; Wijnands, Rudy; Méndez, Mariano +1 more
We report on XMM-Newton observations performed on 2001 September 13-14 of the neutron star X-ray transient KS 1731-260 in quiescence. The source was detected at an unabsorbed 0.5-10 keV flux of only (4-8)×10-14 ergs cm-2 s-1, depending on the model used to fit the data, which for a distance of 7 kpc implies a 0.5-1…
Tomography of the Solar Corona. II. Robust, Regularized, Positive Estimation of the Three-dimensional Electron Density Distribution from LASCO-C2 Polarized White-Light Images
Frazin, Richard A.; Janzen, Paul
Solar rotational tomography is used to determine the three-dimensional electron density distribution of the solar corona from 2.4 to 6.0 Rsolar. The robust, regularized, positive estimation method, described in a previous paper, is demonstrated on test cases and on LASCO-C2 data. Because the solar rotational pole is inclined to the plan…
Lyα Absorption around Nearby Galaxies
Bowen, David V.; Pettini, Max; Blades, J. Chris
We have used the Space Telescope Imaging Spectrograph (STIS) aboard the Hubble Space Telescope to search for Lyα absorption lines in the outer regions of eight nearby galaxies using background quasars and AGNs as probes. Lyα lines are detected within a few hundred kilometers per second of the systemic velocity of the galaxy in all cases. We conclu…
Are Starburst Galaxies the Hosts of Gamma-Ray Bursts?
Chary, R.; Armus, L.; Becklin, E. E.
We present deep 2.2 µm imaging of 12 gamma-ray burst host galaxies. Template spectral energy distributions are fitted to the multiband photometry between visible and near-infrared wavelengths to derive a better constraint on the stellar mass of these galaxies. The internal extinction in the host galaxies is estimated using the rest-frame ult…
ISOCAM Observations of Galactic Globular Clusters: Mass Loss along the Red Giant Branch
Ferraro, Francesco R.; Origlia, Livia; Fusi Pecci, Flavio +1 more
Deep images in the 10 µm spectral region have been obtained for five massive Galactic globular clusters, NGC 104 (=47 Tuc), NGC 362, NGC 5139 (=ω Cen), NGC 6388, NGC 7078 (=M15), and NGC 6715 (=M54) in the Sagittarius Dwarf Spheroidal using the ISOCAM on board the Infrared Space Observatory in 1997. A significant sample of bright giants have…
The Lower Main Sequence and Mass Function of the Globular Cluster Messier 4
Rich, R. Michael; Gibson, Brad K.; Stetson, Peter B. +9 more
The deepest optical image ever in a globular star cluster, a Hubble Space Telescope 123 orbit exposure in a single field of Messier 4, was obtained in two filters (F606W, F814W) over a 10 week period in early 2001. A somewhat shallower image obtained in 1995 allowed us to select out cluster and field objects via their proper-motion displacement, r…
The Large-Scale Coronal Field Structure and Source Region Features for a Halo Coronal Mass Ejection
Shibata, K.; Kurokawa, H.; Yan, Yihua +2 more
On 1998 May 2 a class X1/3B flare occurred at 13:42 UT in NOAA Active Region 8210 near disk center, which was followed by a halo coronal mass ejection (CME) at 15:03 UT observed by SOHO/LASCO. Using the boundary element method (BEM) on a global potential model, we reconstruct the large-scale coronal field structure from a composite boundary by SOH…
Fundamental Properties and Distances of the Large Magellanic Cloud from Eclipsing Binaries. II. HV 982
Ribas, I.; Fitzpatrick, E. L.; Massa, D. +3 more
We have determined the distance to a second eclipsing binary (EB) system in the Large Magellanic Cloud, HV 982 (~B1 IV-V+~B1 IV-V). The measurement of the distance-among other properties of the system-is based on optical photometry and spectroscopy and space-based UV/optical spectrophotometry. The analysis combines the ``classical'' EB study of li…
The Inadequacy of Temperature Measurements in the Solar Corona through Narrowband Filter and Line Ratios
Schmelz, J. T.; Martens, P. C. H.; Cirtain, J. W.
We analyze the determination of coronal line-of-sight temperatures with the technique of narrowband filter ratios that is currently employed for data obtained with the Transition Region and Coronal Explorer and the EUV Imaging Telescope on board the Solar and Heliospheric Observatory. We demonstrate that the simple fact that the observed different…
The First Detections of the Extragalactic Background Light at 3000, 5500, and 8000 Å. III. Cosmological Implications
Madore, Barry F.; Freedman, Wendy L.; Bernstein, Rebecca A.
We have used the Hubble Space Telescope Wide Field and Planetary Camera 2 in combination with ground-based spectroscopy to measure the integrated flux of galaxies at optical wavelengths-the extragalactic background light (EBL). We have also computed the integrated light from individual galaxy counts in the images used to measure the EBL and in the…