Search Publications
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. …
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<…
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…
Discovery of a Transient X-Ray Source in the Compact Stellar Nucleus of NGC 2403
Soria, Roberto; Tennant, Allyn F.; Swartz, Douglas A. +1 more
We report the discovery of an X-ray source coincident with the nuclear star cluster at the dynamical center of the nearby late-type spiral galaxy NGC 2403. The X-ray luminosity of this source varies from below detection levels, ~1035 erg s-1 in the 0.5-8.0 keV band to 7×1038 erg s-1 on timescales between…
Emission-Line Gas Kinematics in the Vicinity of the Supermassive Black Holes in Nearby Radio Galaxies
Baum, Stefi A.; O'Dea, Christopher P.; Noel-Storr, Jacob
We describe our characterization of the kinematics of the emission-line gas in the nuclear regions of a complete sample of 21 nearby radio galaxies. We obtained data using the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope. We show that the point-to-point variations are largest perpendicular to the disks and in nuclei whe…
Hubble Space Telescope Measurements of Vacuum Ultraviolet Lines of Interstellar CH
Federman, S. R.; Sheffer, Y.
Three interstellar absorption lines near 1370 Å seen toward ζ Oph have been assigned by Watson to Rydberg transitions in the G-X (or 3d-X) band of CH. Our survey of a dozen diffuse interstellar lines of sight shows that the three absorption lines are consistent with the known column densities of CH, by deriving the following oscillator strengths: …
The Physical Properties of Coronal Streamers. II.
Uzzo, M.; Vourlidas, A.; Strachan, L.
In this paper the plasma properties of three streamers observed in 2003 by the Ultraviolet Coronagraph Spectrometer (UVCS) are presented for five heights from 1.75 to 5.0 Rsolar. The kinetic temperatures for protons (Tk,p) and the O5+ ions (Tk,O) are derived as a function of height with preferential heat…
Serendipitous XMM-Newton Discovery of a Cluster of Galaxies at z = 0.28
Barth, Aaron J.; Humphrey, Philip J.; Buote, David A. +5 more
We report the discovery of a galaxy cluster serendipitously detected as an extended X-ray source in an offset observation of the group NGC 5044. The cluster redshift, z=0.281, determined from the optical spectrum of the brightest cluster galaxy, agrees with that inferred from the X-ray spectrum using the Fe Kα complex of the hot ICM (z=0.27+/-0.01…
Runaway Massive Binaries and Cluster Ejection Scenarios
Ransom, Scott M.; Boyajian, Tabetha S.; Grundstrom, Erika D. +2 more
The production of runaway massive binaries offers key insights into the evolution of close binary stars and open clusters. The stars HD 14633 and HD 15137 are rare examples of such runaway systems, and in this work we investigate the mechanism by which they were ejected from their parent open cluster, NGC 654. We discuss observational characterist…
Empirical Solar Wind Forecasting from the Chromosphere
McIntosh, S. W.; Leamon, R. J.
Recently, we correlated the inferred structure of the solar chromospheric plasma topography with solar wind velocity and composition data measured at 1 AU. We now offer a physical justification of these relationships and present initial results of an empirical prediction model based on them. While still limited by the fundamentally complex physics…