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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…
Jet-Driven Motions in the Narrow-Line Region of NGC 1068
Marconi, A.; Macchetto, F. D.; Capetti, A. +3 more
We have obtained Hubble Space Telescope Faint Object Camera (FOC) f/48 long-slit spectroscopy of the inner 4" of the narrow-line region (NLR) of NGC 1068 between 3500 and 5400 Å with a spectral resolution of 1.78 Å pixel-1. At a spatial scale of 0.0287" pixel-1 these data provide an order-of-magnitude improvement in resolutio…
The Extragalactic Distance Scale Key Project. XVI. Cepheid Variables in an Inner Field of M101
Kelson, Daniel D.; Illingworth, Garth D.; Huchra, John P. +20 more
We report on the identification of 255 candidate variable stars in a field located some 1.7 arcmin from the center of the late-type spiral galaxy M101 = NGC 5457, based on observations made with the Wide Field and Planetary Camera 2 on board the Hubble Space Telescope. Photometric measurements in the F555W and F814W filters--analyzed independently…
Clustering at High Redshift: Precise Constraints from a Deep, Wide-Area Survey
Lauer, Tod R.; Oegerle, William; Postman, Marc +1 more
We present constraints on the evolution of large-scale structure from a catalog of 710,000 galaxies with IAB <= 24 derived from a KPNO 4 m CCD imaging survey of a contiguous 4° × 4° region. The advantage of using large contiguous surveys for measuring clustering properties on even modest angular scales is substantial: the effects of …
Galactic Cosmic-Ray Confinement Time: Ulysses High Energy Telescope Measurements of the Secondary Radionuclide 10Be
Connell, J. J.
We report new measurements of the isotopic abundances of the Galactic cosmic-ray isotopes 7Be, 9Be, and radioactive 10Be. These measurements from the Ulysses High Energy Telescope (HET) combine exceptional mass resolution with superior statistics. Measurements of radioisotopes produced as secondaries during cosmic-…
Revised ages for stars in the solar neighbourhood
Bertelli, G.; Ng, Y. K.
New ages are computed for the stars from the Edvardsson et al. (1993) data set. The revised values are systematically larger toward older ages (t>4 Gyr), while they are slightly lower for t<4 Gyr. A similar, but considerably smaller trend is present when the ages are computed with the distances based on Hipparcos parallaxes. The resulting ag…
Solar internal rotation rate and the latitudinal variation of the tachocline
Basu, Sarbani; Antia, H. M.; Chitre, S. M.
A new set of accurately measured frequencies of solar oscillations is used to infer the rotation rate inside the Sun, as a function of radial distance as well as latitude. We have adopted a regularized least-squares technique with iterative refinement for both 1.5D inversion, using the splitting coefficients, and 2D inversion using individual m sp…
ΔY/ΔZ from fine structure in the main sequence based on Hipparcos parallaxes
Pagel, B. E. J.; Portinari, L.
The slope ΔY/ΔZ is a quantity of interest in relation to stellar evolution, the initial mass function and the determination of the primordial helium abundance. In this paper we estimate ΔY/ΔZ from fine structure in the main sequence of nearby stars from Hipparcos data for stars with Z<=Zsolar. We find a value of about 3, which is consistent wit…
The Castor moving group. The age of Fomalhaut and VEGA
Barrado y Navascues, D.
We have recomputed the kinematic properties of several of dozens nearby stars, to try to verify if Castor (alpha Gem) indeed has a cohort of stars sharing the same space motion and age. We used kinematics, the location of the stars in Color-Magnitude Diagrams, their lithium abundances, and their activity, to establish that the moving group seems t…
The Recent Star Formation History of GR 8 from Hubble Space Telescope Photometry of the Resolved Stars
Saha, A.; Gallagher, J.; Mateo, Mario +6 more
We have used the Hubble Space Telescope to observe the resolved stars in the dwarf irregular galaxy GR 8 (DDO 155, UGC 8091). The data consisted of dithered Wide Field Planetary Camera 2 images in three bands: F439W (1 hr), F555W (30 minutes), and F814W (30 minutes). The stellar photometry was extracted with a modified version of DoPHOT. Artificia…