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Dusty Nuclear Disks and Filaments in Early-Type Galaxies
Jaffe, W.; Ford, H. C.; van den Bosch, F. C. +4 more
We examine the dust properties of a nearby distance-limited sample of early-type galaxies using WFPC2 of the Hubble Space Telescope. Dust is detected in 29 out of 67 galaxies (43%), including 12 with small nuclear dusty disks. In a separate sample of 40 galaxies biased for the detection of dust by virtue of their detection in IRAS 100 µm ban…
Spectrophotometric Standards from the Far-Ultraviolet to the Near-Infrared: STIS and NICMOS Fluxes
Calzetti, D.; Dickinson, M. E.; Bohlin, R. C.
With photometric repeatability in the 0.2%-0.4% range and wavelength coverage from 1150 to 10,200 Å, the Space Telescope Imaging Spectrograph (STIS) low-dispersion spectrophotometry provides excellent absolute flux standards. STIS observations of 19 stars are used to update the database of Hubble Space Telescope standard stars with absolute fluxes…
New Insights on the Draco Dwarf Spheroidal Galaxy from the Sloan Digital Sky Survey: A Larger Radius and No Tidal Tails
Grebel, Eva K.; York, Donald G.; Holtzman, Jon +20 more
We have investigated the spatial extent and structure of the Draco dwarf spheroidal galaxy by using deep wide-field multicolor CCD photometry from the Sloan Digital Sky Survey (SDSS). Our study covers an area of 27 deg2 around the center of the Draco dwarf and reaches 2 mag below the level of Draco's horizontal branch. The SDSS photomet…
The Line-of-Sight Depth of Populous Clusters in the Small Magellanic Cloud
Piatti, Andrés E.; Sarajedini, Ata; Geisler, Doug +4 more
We present an analysis of age, metal abundance, and positional data on populous clusters in the Small Magellanic Cloud (SMC) with the ultimate aim of determining the line-of-sight (LOS) depth of the SMC by using these clusters as proxies. Our data set contains 12 objects and is limited to clusters with the highest-quality data for which the ages a…
The Shape and Orientation of the Homunculus Nebula Based on Spectroscopic Velocities
Hillier, D. J.; Smith, Nathan; Gull, Theodore R. +2 more
Doppler velocities give information about the three-dimensional shape and orientation of the bipolar ejecta of η Car. We report slit spectroscopy obtained using the Space Telescope Imaging Spectrograph (HST/STIS), with spatial resolution adequate for good models. These data allow an independent estimate of the distance to this object. Equatorial v…
An Abundance Analysis for Four Red Horizontal-Branch Stars in the Extremely Metal-Rich Globular Cluster NGC 6528
Cohen, Judith G.; Carretta, Eugenio; Gratton, Raffaele G. +1 more
We present the results of the first analysis of high-dispersion spectra of four red horizontal-branch stars in the metal-rich globular cluster NGC 6528, located in Baade's window. We find that the mean [Fe/H] for NGC 6528 is +0.07+/-0.01 dex (error of the mean), with a star-to-star scatter of σ=0.02 dex (four stars), although the total error is li…
The Physical Basis of Luminosity Classification in the Late A-, F-, and Early G-Type Stars. II. Basic Parameters of Program Stars and the Role of Microturbulence
Gray, R. O.; Graham, P. W.; Hoyt, S. R.
Paper I of this series presented precise MK spectral types for 372 late A-, F-, and early G-type stars with the aim of understanding the nature of luminosity classification on the MK spectral classification system for this range of spectral types. In this paper, a multidimensional downhill simplex technique is introduced to determine the basic par…
The Globular Cluster System in the Outer Regions of NGC 4472
Zepf, Stephen E.; Rhode, Katherine L.
We have undertaken a study of the globular cluster (GC) systems of a large sample of elliptical and spiral galaxies in order to test specific predictions of galaxy formation models. Here we present results for the first elliptical in the study, the giant Virgo cluster galaxy NGC 4472 (M49). The galaxy was observed in three filters (BVR) using the …
Radial Velocity Studies of Close Binary Stars. IV.
Rucinski, Slavek M.; Lu, Wenxian; Ogłoza, Waldemar
Radial velocity measurements and sine-curve fits to the orbital velocity variations are presented for the fourth set of 10 close binary systems: 44 Boo, FI Boo, V2150 Cyg, V899 Her, EX Leo, VZ Lib, SW Lyn, V2377 Oph, Anon Psc (GSC 8-324), and HT Vir. All systems are double-lined spectroscopic binaries, with only two of them not being contact syste…
The Spatial Distribution of O-B5 Stars in the Solar Neighborhood as Measured by Hipparcos
Maíz-Apellániz, Jesús
We have developed a method to calculate the fundamental parameters of the vertical structure of the Galaxy in the solar neighborhood from trigonometric parallaxes alone. The method takes into account Lutz-Kelker-type biases in a self-consistent way and has been applied to a sample of O-B5 stars obtained from the Hipparcos catalog. We find that the…