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Speckle Observations of Binary Stars with the WIYN Telescope. I. Measures During 1997
Girard, Terrence M.; van Altena, William F.; Horch, Elliott +3 more
Two hundred seventy-seven position angle and separation measures of 154 double stars are presented. Three of the systems were previously unknown to be double, and 16 other systems were discovered earlier this decade by the Hipparcos satellite. Measures are derived from speckle observations taken with the Wisconsin-Indiana-Yale-NOAO (WIYN) 3.5 m te…
The Multiple Phases of Interstellar and Halo Gas in a Possible Group of Galaxies at Z~1
Charlton, Jane C.; Churchill, Christopher W.
We used HIRES/Keck profiles (R~6 km s^-1) of Mg II and Fe II in combination with Hubble Space Telescope (HST) Faint Object Spectrograph (FOS) spectra (R~230 km s^-1) to place constraints on the physical conditions (metallicities, ionization conditions, and multiphase distribution) of absorbing gas in three galaxies at z=0.9254, 0.9276, and 0.9343 …
A Goddard High Resolution Spectrograph Atlas of Echelle Observations of the HGMN Star chi LUPI
Savage, B. D.; Ebbets, D. C.; Nilsson, H. +20 more
Observations of the ultra-sharp-lined, chemically peculiar star chi Lupi taken by the Goddard High Resolution Spectrograph in echelle mode are presented. Thirty-six intervals of the spectral region between 1249 and 2688 Å are covered with resolving powers in the range 75,000-93,000. Line identifications are provided, and the observed spectra are c…
HUBBLE SPACE TELESCOPE Imaging of Globular Clusters in the Edge-on Spiral Galaxies NGC 4565 and NGC 5907
Zepf, Stephen E.; Freeman, Kenneth C.; Kissler-Patig, Markus +1 more
We present a study of the globular cluster systems of two edge-on spiral galaxies, NGC 4565 and NGC 5907, from WFPC2 images in the F450W and F814W filters. The globular cluster systems of both galaxies appear to be similar to the Galactic globular cluster system. In particular, we derive total numbers of globular clusters of N_GC(4565)=204+/-38^+8…
The Structure and Morphology of the Ionized Gas in Starburst Galaxies: NGC 5253/5236
Conselice, Christopher J.; Calzetti, Daniela; Gallagher, John S., III +1 more
We investigate the interplay between starbursts and host galaxies by studying the structure and physical characteristics of the ionized gas surrounding the central starbursts in the two nearby galaxies NGC 5253 and NGC 5236. The two systems form a pair that presumably interacted about 1 Gyr ago. They represent very different galactic environments,…
HUBBLE SPACE TELESCOPE Observations of Galactic Globular Cluster Cores. I. NGC 6362 and NGC 6934
Djorgovski, S. G.; Zoccali, M.; Rich, R. M. +5 more
We present observations of the centers of the Galactic globular clusters NGC 6362 and NGC 6934 obtained with the Hubble Space Telescope/Wide Field Planetary Camera 2 as part of the snapshot program GO-7470. The B, V color-magnitude diagrams (CMDs) are presented for 4104 stars in NGC 6362 and for 8187 stars in NGC 6934. From the CMDs, we obtain (m-…
Stellar Populations in the Dwarf Spheroidal Galaxy Leo I
Cassisi, Santi; Castellani, Marco; Caputo, Filippina +2 more
We present a detailed study of the color-magnitude diagram (CMD) of the dwarf spheroidal galaxy Leo I, based on archival Hubble Space Telescope data. Our photometric analysis, confirming previous results on the brighter portion of the CMD, also allow us to obtain an accurate sampling of the stellar populations at the faint magnitudes corresponding…
The Effective Temperature of Arcturus
Lynas-Gray, A. E.; Griffin, R. E. M.
We construct an empirical energy distribution for Arcturus from published scans, integrate it to obtain the total flux, and combine the latter with precise interferometric measurements of the limb-darkened angular diameter to derive the effective temperature. We conclude that the best value that can be derived within the framework of the associate…
Dust in Spiral Galaxies: Comparing Emission and Absorption to Constrain Small-Scale and Very Cold Structures
Ryder, Stuart D.; White, Raymond E., III; Keel, William C. +1 more
The detailed distribution of dust in the disks of spiral galaxies is important to understanding the radiative transfer within disks and to measuring overall dust masses if significant quantities of dust are either very opaque or very cold. We address this issue by comparing measures of dust absorption, using the galaxy-overlap technique in the opt…
The Ionizing Star Clusters of Giant H II Regions in NGC 2403
Drissen, Laurent; Moffat, Anthony F. J.; Shara, Michael M. +1 more
We present the results of a study on the massive star population down to about M_V~-3.1, or 12-15 M_solar, of the most luminous giant H II regions in the nearby spiral galaxy NGC 2403, based on Hubble Space Telescope images and ground-based spectrograms. Particular emphasis is placed on the distribution of the Wolf-Rayet and red supergiant stars a…