Search Publications
INTEGRAL detection of a long powerful burst from SLX 1735-269
Sunyaev, R.; Revnivtsev, M.; Lutovinov, A. +1 more
We present results of an analysis of the bursting behavior of the low mass X-ray binary system SLX 1735-269 during INTEGRAL observations of the Galactic Center region in 2003. Six type-I X-ray bursts were detected in total with one being much longer and more powerful then the others. A strong dependence of the burst recurrence time on the mass acc…
Interstellar Ca II Line Intensities and the Distances of the OB stars
Galazutdinov, G. A.; Han, Inwoo; Strobel, A. +4 more
We show that the equivalent widths of the well-known interstellar Ca II H and K lines can be used to determine the distances to OB stars in our Galaxy. The equivalent widths, measured in the spectra of 147 early-type stars, are strongly related to the Hipparcos parallaxes of those objects. The lines fitted to the parallax-equivalent width data are…
Effect of the H I Lyα Chromospheric Flux Anisotropy on the Total Intensity of the Resonantly Scattered Coronal Radiation
Auchère, F.
In modeling of the resonantly scattered solar coronal Lyα line of H I, the intensity of the chromospheric source is often assumed to be uniform. We investigate the validity of this assumption. After establishing a correlation between the H I 121.6 nm and He II 30.4 nm line intensities, we build Carrington maps of the Lyα chromosphere from SOHO EUV…
Solar limb faculae
Hirzberger, J.; Wiehr, E.
We observe solar limb faculae at an unprecedented spatial resolution with the new 1 m Swedish Solar Telescope SST on La Palma. Speckle-reconstructed images are used to study 4475 limb facular grains simultaneously in the 430 nm G-band and the 587.5±1.5 continuum up to only 1'' from the limb (cos θ=0.05). No systematic contrast decrease is found ev…
Deconstructing NGC 7130
Heckman, T. M.; Levenson, N. A.; Weaver, K. A. +2 more
Observations of the Seyfert 2 and starburst galaxy NGC 7130 with the Chandra X-Ray Observatory illustrate that both of these phenomena contribute significantly to the galaxy's detectable X-ray emission. The active galactic nucleus (AGN) is strongly obscured, buried beneath column density NH>1024cm-2, and it is m…
Far Ultraviolet Spectroscopic Explorer Measurements of Interstellar Fluorine
Federman, S. R.; Lambert, David L.; Smith, V. V. +1 more
The source of fluorine is not well understood, although core-collapse supernovae, Wolf-Rayet stars, and asymptotic giant branch stars have been suggested. A search for evidence of the ν-process during Type II supernovae is presented. Absorption from interstellar F I is seen in spectra of HD 208440 and HD 209339A acquired with the Far Ultraviolet S…
The Ultraviolet Spectrum of η Carinae: Investigation of the Ejecta Absorption
Gull, T. R.; Nielsen, K. E.; Vieira Kober, G.
We have investigated the far- through mid-UV (1150-2360 Å) spectrum of η Carinae during the late stages of its broad maximum using the Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS) moderate dispersion echelle modes. The η Car spectrum is a mixture of absorption and emission lines from the surrounding nebula superimposed …
Nonlinear Alfvén, magnetosonic, sound, and electron inertial waves in fluid formalism
Stasiewicz, K.
A fluid model of nonlinear electron and ion inertial waves in anisotropic plasmas is presented. The model has been verified for plasma beta (ratio of kinetic/magnetic pressures) in a range between 0.1 and 15. It is shown that warm plasmas support four types of nonlinear waves, which correspond to four linear modes, Alfvénic, magnetosonic, sound, a…
Metallicities of the β Cephei stars from low-resolution ultraviolet spectra
Niemczura, E.; Daszyńska-Daszkiewicz, J.
We derive basic stellar parameters (angular diameters, effective temperatures, metallicities) and interstellar reddening for all β Cephei stars observed during the IUE satellite mission, including those belonging to three open clusters. The parameters are derived by means of an algorithmic procedure of fitting theoretical flux distributions to the…
On the Afterglow and Host Galaxy of GRB 021004: A Comprehensive Study with the Hubble Space Telescope
Pian, E.; Kouveliotou, C.; Tanvir, N. +24 more
We report on Hubble Space Telescope (HST) observations of the late-time afterglow and host galaxy of GRB 021004 (z=2.33). Although this gamma-ray burst (GRB) is one of the best observed so far in terms of sampling in the time domain, multiwavelength coverage, and polarimetric observations, there is substantial disagreement between different interp…