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Keck Spectroscopy of Candidate 97Proto-Globular Clusters in NGC 1275
Forbes, Duncan A.; Brodie, Jean P.; Huchra, John P. +3 more
Keck spectroscopy of five proto-globular cluster candidates in NGC 1275 has been combined with Hubble Space Telescope Wide Field Planetary Camera 2 photometry to explore the nature and origin of these objects and discriminate between merger and cooling-flow scenarios for globular cluster formation. The objects we have studied are not H ii regions,…
H i 21 Centimeter Absorption in Two Low-Redshift Damped Lyalpha Systems
Turnshek, D.; Meylan, G.; Smette, A. +3 more
We report the discovery of two low-redshift H i 21 cm absorbers, one at z = 0.2212 toward the z_em = 0.630 quasar OI 363 (B0738+313), and the other at z = 0.3127 toward PKS B1127-145 (z_em = 1.187). Both were found during a survey of Mg ii-selected systems at redshifts 0.2 < z < 1 using the new UHF-high system at the Westerbork Synthesis Rad…
Red Clump Morphology as Evidence against a New Intervening Stellar Population as the Primary Source of Microlensing toward the Large Magellanic Cloud
Beaulieu, Jean-Philippe; Sackett, Penny D.
We examine the morphology of the color-magnitude diagram (CMD) for core helium burning (red clump) stars to test the recent suggestion by Zaritsky & Lin that an extension of the red clump in the Large Magellanic Cloud (LMC) toward brighter magnitudes is the result of an intervening population of stars that is responsible for a significant frac…
The Mass Distribution in the Elliptical Galaxy NGC 3377: Evidence for a 2 X 10^8 M_⊙ Black Hole
Richstone, Douglas; Kormendy, John; Bender, Ralf +1 more
This paper is a study of the mass distribution in the central 35" ~= 1.7 kpc of the E5 galaxy NGC 3377. Stellar rotation velocity and velocity dispersion profiles (seeing sigma_* = 0.20"-0.56") and V-band surface photometry (sigma_* = 0.20"-0.26") have been obtained with the Canada-France-Hawaii Telescope. NGC 3377 is kinematically similar to M32:…
Three Populous Clusters Discovered in the Large Magellanic Cloud Age Gap
Sarajedini, Ata
In the process of searching the Hubble Space Telescope archive, we have serendipitously discovered three populous Large Magellanic Cloud (LMC) clusters with ages that place them in the LMC ``age gap.'' These clusters-NGC 2155, SL 663, and NGC 2121-turn out to have [Fe/H] ~ -1.0 and ages of ~4 Gyr. This puts them in the ``age gap'' between the inte…
A Hubble Space Telescope Study of Extragalactic OB Associations
Macri, Lucas M.; Gibson, Brad K.; Stetson, Peter B. +9 more
We present a study of OB associations, identified by objective means, in seven spiral galaxies observed with the Hubble Space Telescope as part of the Key Project on the distance scale. The properties of the associations, including their size distribution and average diameter, and the luminosity function of their brightest stars, do not vary signi…
The Intervening and Associated O VI Absorption-Line Systems in the Ultraviolet Spectrum of H1821+643
Tripp, Todd M.; Savage, Blair D.; Lu, Limin
GHRS and FOS ultraviolet spectra of the bright QSO H1821+643 (m_V = 14.2, z_em = 0.297) reveal the presence of strong O vi lambdalambda1031.93, 1037.62 absorption systems at z_abs = 0.225 and 0.297, the latter being at the redshift of the QSO itself. Ground-based galaxy redshift measurements by us and others reveal two emission-line galaxies near …
Hubble Space Telescope Wide Field Planetary Camera 2 Observations of HH 1-2
Hester, J. Jeff; Stapelfeldt, Karl R.; Scowen, Paul A.
We present Hubble Space Telescope Wide Field Planetary Camera 2 images of the bipolar Herbig-Haro complex HH 1-2 in three emission lines (Hα, [S ii], and [O iii]) and one continuum band (F702W). In addition to showing the complex morphology of these objects, the WFPC2 data allow us to resolve the cooling and recombination regions behind radiative …
A New Analysis of RR Lyrae Kinematics in the Solar Neighborhood
Martin, John C.; Morrison, Heather L.
Full space velocities are computed for a sample of 130 nearby RR Lyrae variables using both ground-based and Hipparcos proper motions. In many cases proper motions for the same star from multiple sources have been averaged to produce approximately a factor of 2 improvement in the transverse space velocity errors. In most cases, this exceeds the ac…
The Ultracompact H II Region G5.97-1.17: an Evaporating Circumstellar Disk in M8
Henning, T.; Stecklum, B.; Hayward, T. L. +4 more
We present new high spatial resolution optical, infrared, and radio observations of G5.97-1.17, an ultracompact H ii region 2.7" distant from the O7 star Herschel 36 in the center of M8, the Lagoon Nebula. Infrared imaging was obtained using the adaptive optics system ADONIS on the ESO 3.6 m telescope and a thermal-IR camera on the Hale 5 m; optic…