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Chemical composition of 90 F and G disk dwarfs
Zhao, G.; Nissen, P. E.; Chen, Y. Q. +2 more
High resolution, high S/N spectra have been obtained for a sample of 90 F and G main-sequence disk stars covering the metallicity range -1.0 < [Fe/H] < +0.1, and have been analysed in a parallel way to the work of Edvardsson et al. (\cite{Edvardsson93a}) in order to re-inspect their results and to reveal new information on the chemical evolu…
The Evolution of the Galactic Morphological Types in Clusters
Couch, Warrick J.; Poggianti, Bianca M.; Fasano, Giovanni +3 more
The morphological types of galaxies in nine clusters in the redshift range 0.1<~z<~0.25 are derived from very good seeing images taken at the NOT and the La Silla-Danish telescopes, with all galaxies at MV<-20 and within the central ~1 Mpc2 area being classified. With the purpose of investigating the evolution of the…
Mapping the Evolution of High-Redshift Dusty Galaxies with Submillimeter Observations of a Radio-selected Sample
Barger, A. J.; Cowie, L. L.; Richards, E. A.
Direct submillimeter imaging has recently revealed the 850 µm background to be mostly composed of a population of distant ultraluminous infrared galaxies, but identifying the optical/near-infrared (NIR) counterparts to these sources has proved difficult because of the poor submillimeter spatial resolution. However, the proportionality of bot…
Cosmic protons
Usoskin, I.; Laitinen, T.; Valtonen, E. +200 more
The primary proton spectrum in the kinetic energy range 0.2 to 200 GeV was measured by the Alpha Magnetic Spectrometer (AMS) during space shuttle flight STS-91 at an altitude of 380 km. The complete data set combining three shuttle attitudes and including all known systematic effects is presented.
Hubble Space Telescope Photometry and Keck Spectroscopy of the Rich Cluster MS 1054-03: Morphologies, Butcher-Oemler Effect, and the Color-Magnitude Relation at Z = 0.83
van Dokkum, Pieter G.; Franx, Marijn; Kelson, Daniel D. +2 more
We present a study of 81 I-band selected, spectroscopically confirmed members of the X-ray cluster MS 1054-03 at z=0.83. Redshifts and spectral types were determined from Keck spectroscopy. Morphologies and accurate colors were determined from a large mosaic of HST WFPC2 images in RF606W and IF814W, corresponding to U and B i…
The Surface Brightness Fluctuation Survey of Galaxy Distances. II. Local and Large-Scale Flows
Ajhar, Edward A.; Dressler, Alan; Tonry, John L. +1 more
We present results from the Surface Brightness Fluctuation (SBF) Survey for the distances to 300 early-type galaxies, of which approximately half are ellipticals. A modest change in the zero point of the SBF relation, derived by using Cepheid distances to spirals with SBF measurements, yields a Hubble constant H0=77+/-4+/-7 km s-1<…
WFPC2 Observations of the Hubble Deep Field South
Dickinson, Mark; Ferguson, Henry C.; Lucas, Ray A. +14 more
The Hubble Deep Field South (HDF-S) observations targeted a high Galactic latitude field near QSO J2233-606. We present Wide Field Planetary Camera 2 observations of the field in four wide bandpasses centered at roughly 300, 450, 606, and 814 nm. Observations, data reduction procedures, and noise properties of the final images are discussed in det…
Large-Angle Spectrometric Coronagraph Measurements of the Energetics of Coronal Mass Ejections
Howard, R. A.; Dere, K. P.; Vourlidas, A. +1 more
We examine the energetics of coronal mass ejections (CMEs) with data from the large-angle spectrometric coronagraphs (LASCO) on SOHO. The LASCO observations provide fairly direct measurements of the mass, velocity, and dimensions of CMEs. Using these basic measurements, we determine the potential and kinetic energies and their evolution for severa…
The Hubble Space Telescope Key Project on the Extragalactic Distance Scale. XXVI. The Calibration of Population II Secondary Distance Indicators and the Value of the Hubble Constant
Kelson, Daniel D.; Illingworth, Garth D.; Madore, Barry F. +14 more
A Cepheid-based calibration is derived for four distance indicators that utilize stars in old stellar populations: the tip of the red giant branch (TRGB), the planetary nebula luminosity function (PNLF), the globular cluster luminosity function (GCLF), and the surface brightness fluctuation method (SBF). The calibration is largely based on the Cep…
Time-Distance Inversion Methods and Results - (Invited Review)
Kosovichev, A. G.; Scherrer, P. H.; Duvall, T. L. _Jr., Jr.
The current interpretations of the travel-time measurements in quiet and active regions on the Sun are discussed. These interpretations are based on various approximations to the 3-D wave equation such as the Fermat principle for acoustic rays and the Born approximation. The ray approximation and its modifications have provided the first view of t…