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ICCD Speckle Observations of Binary Stars. XIX. an Astrometric/Spectroscopic Survey of O Stars
Gies, Douglas R.; Bagnuolo, William G., Jr.; Mason, Brian D. +3 more
We present the results of a speckle interferometric survey made with the CHARA speckle camera and 4 m-class telescopes of Galactic O-type stars with V < 8. We can detect with the speckle camera binaries in the angular separation range 0.035" < rho < 1.5" with Deltam < 3, and we have discovered 15 binaries among 227 O-type systems. We c…
The Distribution of Nearby Stars in Velocity Space Inferred from HIPPARCOS Data
Dehnen, Walter
The velocity distribution f(v) of nearby stars is estimated, via a maximum likelihood algorithm, from the positions and tangential velocities of a kinematically unbiased sample of 14,369 stars observed by the Hipparcos satellite. The distribution f shows rich structure in the radial and azimuthal motions, v_R and v_phi, but not in the vertical vel…
The ACT Reference Catalog
Urban, S. E.; Wycoff, G. L.; Corbin, T. E.
The US Naval Observatory has completed the compilation of the ACT Reference Catalog, containing 988,758 stars covering the entire sky. The motivation behind the ACT was to provide accurate proper motions for the majority of the stars in the Tycho Catalogue. To do this, positions from new reductions of the Astrographic Catalogue (AC 2000) were comb…
HIPPARCOS Subdwarf Parallaxes: Metal-rich Clusters and the Thick Disk
Reid, Neill
We have used main-sequence fitting to calibrate the distances to the globular clusters NGC 6397, M5, NGC 288, M71, and 47 Tucanae, matching the cluster photometry against data for subdwarfs with precise Hipparcos parallax measurements and accurate abundance determinations. Both the cluster and subdwarf abundance scales are tied to high-resolution …
The AC 2000: The Astrographic Catalogue on the System Defined by the HIPPARCOS Catalogue
Urban, S. E.; Wycoff, G. L.; Martin, J. C. +4 more
The AC 2000 is a positional catalog of 4,621,836 stars covering the entire sky. The average epoch of position is 1907. The data are from the images measured and published as part of the Astrographic Catalogue (AC). The positions are on the system defined by the Hipparcos Catalogue, having originally been reduced plate-by-plate using the Astrograph…
Radii and Effective Temperatures for K and M Giants and Supergiants. II.
van Belle, G. T.; Thompson, R. R.; Dyck, H. M.
We present new interferometric observations for 74 luminous red stars, made in the near-infrared. We show that our 2.2 µm uniform-disk diameters agree with other near-infrared diameter determinations (lunar occultations and interferometers) for 22 stars measured in common with ours. From our new data, we derive effective temperatures that ar…
Weak and Post-T Tauri Stars around B-Type Members of the Scorpius-Centaurus OB Association
Martín, E. L.
I report medium-resolution (FWHM = 1.9 Å) spectroscopic observations of six Hα emission-line stars proposed in 1993 by Meyer, Wilking, & Zinnecker to be T Tauri stars formed in the vicinity of the B1 giant sigma Sco, a bright member of the Sco-Cen OB association. Using spectroscopic criteria (spectral types, Hα and Li i equivalent widths), whi…
Navy Prototype Optical Interferometer Observations of the Double Stars Mizar A and Matar
Hajian, Arsen R.; Hutter, D. J.; Hummel, C. A. +3 more
We present a detailed analysis of two spectroscopic binaries based on new observations obtained with the Navy Prototype Optical Interferometer (NPOI). While the data calibration needs refinement, first results show the impressive potential of NPOI, both in terms of speed and precision, for imaging and modeling the orbits of spectroscopic binaries.…
Keck HIRES Spectroscopy of M92 Subgiants: Surprising Abundances near the Turnoff
King, Jeremy R.; Boesgaard, Ann M.; Stephens, Alex +1 more
Using high-resolution, moderate signal-to-noise ratio spectroscopy obtained with the 10 m Keck I Telescope and efficient HIRES echelle spectrograph, we derive abundances of several elements in subgiants near the M92 turnoff. As a consistency check, we also analyze the metal-poor field star HD 140283 and find an Fe abundance in fine agreement with …
Early Evolution of the Galactic Halo Revealed from Hipparcos Observations of Metal-poor Stars
Yoshii, Yuzuru; Chiba, Masashi
The kinematics of 122 red giant and 124 RR Lyrae stars in the solar neighborhood are studied using accurate measurements of their proper motions obtained by the Hipparcos astrometry satellite, combined with their published photometric distances, metal abundances, and radial velocities. A majority of these sample stars have metal abundances of [Fe/…