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Clusters in the Luminous Giant H II Regions in M101
Johnson, Kelsey E.; Chu, You-Hua; Chen, C. -H. Rosie
We have obtained HST WFPC2 observations of three very luminous but morphologically different giant H II regions (GHRs) in M101, NGC 5461, NGC 5462, and NGC 5471, in order to study cluster formation in GHRs. Images obtained in the F547M and F675W bands are used to identify cluster candidates and for photometric measurements, and images in the F656N…
The Hubble Space Telescope ACS Grism Parallel Survey. II. First Results and a Catalog of Faint Emission-Line Galaxies at z<=1.6
Chen, Hsiao-Wen; Spinrad, Hyron; Stern, Daniel +4 more
We present the first results from the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) Grism Parallel Survey, a large program obtaining deep, slitless ACS grism spectroscopy of high-latitude HST parallel fields. We report on 11 high Galactic latitude fields here, each with grism integration times of more than 12 ks. We identify 601 c…
Chemically Decoupled Nuclei in Five Lenticular Galaxies from SAURON Data
Sil'Chenko, O. K.
We analyze data from the SAURON integral-field spectrograph of the William Herschel 4-m telescope for five lenticular galaxies in which we previously found chemically decoupled nuclei from observations with the Multipupil Fiber Spectrograph of the 6-m Special Astrophysical Observatory telescope. In a larger field of view, we confirmed the presence…
Cataclysmic and Close Binaries in Star Clusters. V. Erupting Dwarf Novae, Faint Blue Stars, X-Ray Sources, and the Classical Nova in the Core of M80
Zurek, David R.; Hinkley, Sasha; Shara, Michael M.
Large populations of cataclysmic variables (CVs) in globular clusters have long been predicted, but the number of absolutely certain cluster CVs known in globular clusters is still less than 10. HST and Chandra observers have recently found dozens of CV candidates in several populous globular clusters. Confirmation and characterization of these ca…
Classical novae in outburst: evolution of the ultraviolet emission lines in CO novae
Altamore, A.; González-Riestra, R.; Cassatella, A.
A comparative study is made of the temporal changes of the ionization level in seven CO novae well monitored with the IUE satellite at low resolution. The investigation is based on the evolution of the fluxes in eight strong ultraviolet emission lines covering a wide range of ionization potentials, from Mg II (7.6 eV) to N V (77.5 eV). We find tha…
Discovery of a redshifted X-ray emission line in the symbiotic neutron star binary 4U 1700+24
Sokoloski, J. L.; Tiengo, A.; Miller, J. M. +4 more
We present the spectral analysis of an XMM-Newton observation of the X-ray binary 4U 1700+24, performed during an outburst in August 2002. The EPIC-PN spectrum above 1 keV can be modeled by a blackbody plus Comptonization model, as in previous observations. At lower energies, however, we detect a prominent soft excess, which we model with a broad …
Density Structure of a Preeruption Coronal Flux Rope
Chen, J.; Krall, J.
A density model is developed for a coronal flux rope with a specified magnetic field configuration in the noninteracting limit, for which transverse pressure forces can be neglected and flows are rapid enough (>1 km s-1) to invalidate a hydrostatic solution. In the coronal portion of the flux rope, we find that the plasma density is …
A uniqueness result for a simple force-free magnetic field submitted to a topological constraint
Aly, J. J.
A proof is given of the following statement: if B is a smooth force-free magnetic field contained in a cylindrical domain of axis parallel to z and of star-shaped cross-section, and if B is topologically equivalent to the uniform field B0=B0z, then B=B0. In addition to being a very first step in the general study o…
XMM-Newton Spectroscopy of the Highly Polarized and Luminous Broad Absorption Line Quasar CSO 755
Brandt, W. N.; Vignali, C.; Comastri, A. +4 more
We present the results from XMM-Newton observations of the highly optically polarized broad absorption line quasar (BALQSO) CSO 755. By analyzing its X-ray spectrum with a total of ~3000 photons, we find that this source has the X-ray continuum of a typical radio-quiet quasar, with a photon index of Γ=1.83+0.07-0.06 and a rat…
Three-dimensional estimates of the coronal electron density at times of extreme solar activity
Frazin, R. A.; Butala, M. D.; Kamalabadi, F.
This paper presents quantitative three-dimensional (3-D) reconstructions of the electron density (Ne) in the solar corona between 1.14 and 2.7 solar radii (R⊙) formed from polarized brightness (pB) measurements made by the Mauna Loa Solar Observatory Mark-IV (Mk4) K-coronameter at the time of the extreme solar events of Octob…