Search Publications
Do Recent Supernovae ia Observations Tend to Rule Out all the Cosmologies?
Vishwakarma, Ram Gopal
Dark energy and the accelerated expansion of the universe have been the direct predictions of the distant supernovae Ia observations which are also supported, indirectly, by the observations of the CMB anisotropies, gravitational lensing and the studies of galaxy clusters. Today these results are accommodated in what has become the concordance cos…
Modeling Star Formation History and Chemical Evolution of Resolved Galaxies
Lee, Myung Gyoon; Yuk, In-Soo
We present a new numerical model (SMART) for deriving the star formation history and chemical evolution from the color-magnitude diagrams of resolved stars in galaxies. Our model differs from previous models in that it generates simulated color-magnitude diagrams with the metal enrichment law calculated from the galactic chemical evolution model. …
Rotational state of the nucleus of Comet 9P/Tempel 1: Results from Hubble Space Telescope observations in 2004
Weaver, Harold A.; A'Hearn, Michael F.; Toth, Imre +2 more
The nucleus of Comet 9P/Tempel 1 was first observed with the Hubble Space Telescope (HST) in December 1997 [Lamy, P., Toth, I., A'Hearn, M.F., Weaver, H., Weissman, P.R., 2001. Icarus 154, 337-344], but the temporal coverage was insufficient to determine its rotational period. Because the success of the Deep Impact mission was critically dependent…
Reddening law and interstellar dust properties along Magellanic sight-lines
Zagury, Frédéric
This study establishes that SMC, LMC and Milky Way extinction curves obey the same extinction law which depends on the 2200 Å bump size and one parameter, and generalizes the Cardelli, Clayton and Mathis (Cardelli et al., Astrophys. J. 345, 245, 1989) relationship. This suggests that extinction in all three galaxies is of the same nature. The role…
A Multiwavelength Analysis of the Strong Lensing Cluster RCS 022434-0002.5 at z=0.778
Hoekstra, H.; Yee, H. K. C.; Gladders, M. +6 more
We present the results of two (101 ks total) Chandra observations of the z=0.778 optically selected lensing cluster RCS 022434-0002.5, along with weak lensing and dynamical analyses of this object. An X-ray spectrum extracted within R2500 (362 h-170 kpc) results in an integrated cluster temperature of 5.1+0.9<…
Streamer Belt and Chains as the Main Sources of Quasi-Stationary Slow Solar Wind
Fujiki, K.; Eselevich, M.; Eselevich, V.
Synoptic maps of white-light coronal brightness from SOHO/LASCO C2 and distributions of solar wind velocity obtained from interplanetary scintillation are studied. Regions with velocity V≈300 - 450 km s−1 and increased density N>10 cm−3, typical of the "slow" solar wind originating from the belt and chains of streamers, ar…
Cluster Observations of the Magnetospheric Low-Latitude Boundary Layer and Cusp during Extreme Solar Wind and Interplanetary Magnetic Field Conditions: II. 7 November 2004 ICME and Statistical Survey
Dandouras, I.; Fazakerley, A. N.; Marghitu, O. +6 more
We present a study of the plasma properties inside and dynamics of the low-latitude boundary layer (LLBL)/cusp during the ICME event on 7 November 2004 based on data from the four Cluster spacecraft. The interplanetary magnetic field (IMF) is predominantly strongly northward, up to 50 nT, with some short-duration rotations. The observed LLBL/cusp …
An Illustration of Modeling Cataclysmic Variables: HST, FUSE, and SDSS Spectra of SDSS J080908.39+381406.2
Szkody, Paula; Sion, Edward M.; Hoard, D. W. +4 more
FUSE, HST, and SDSS spectra of the cataclysmic variable SDSS J080908.39+381406.2 provide a spectral flux distribution from 900 to 9200 Å. This data set is used to illustrate procedures for calculating and testing system models. The spectra are not contemporaneous; it is necessary to assume that the combined spectra are representative of the system…
Atypical current sheets and plasma bubbles: A self-consistent kinetic model
Sitnov, M. I.; Swisdak, M.; Guzdar, P. N.
As revealed by CLUSTER observations, thin current sheets in the magnetotail may strongly differ from the conventional Harris profile due to the effects of embedding and bifurcation. At the same time, they often have no signatures of collisionless magnetic reconnection. A universal phenomenon involving such atypical current sheets, which is connect…
Exploring the X-ray spectral variability of MCG-6-30-15 with XMM-Newton
Larsson, J.; Fabian, A. C.; Miniutti, G. +1 more
We present a study of the spectral variability of the Seyfert I galaxy MCG-6-30-15 based on the two long XMM-Newton observations from 2000 and 2001. The X-ray spectrum and variability properties of the 2001 data have previously been well described with a two-component model consisting of a variable power-law and a much less variable reflection com…