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Morphological Evolution of Distant Galaxies from Adaptive Optics Imaging
We report here on a sample of resolved, infrared images of galaxies atz~0.5 taken with the 10 m Keck Telescope's adaptive optics system. Weregularly achieve a spatial resolution of 0.05" and are thus able toresolve both the disk and bulge components. We have extractedmorphological information for 10 galaxies and compared their propertiesto those of a local sample. The selection effects of both samples wereexplicitly taken into account in order to derive the unbiased resultthat disks at z~0.5 are ~0.6 mag arcsec-2 brighter than, andabout the same size as, local disks. The case with no luminosityevolution is ruled out at 90% confidence. We also find, in a morequalitative analysis, that the bulges of these galaxies have undergone asmaller amount of surface brightness evolution and have also not changedsignificantly in size from z~0.5 to today. This is the first time thistype of morphological evolution has been measured in the infrared and itpoints to the unique power of AO in exploring galaxy evolution.
| Faint Field Galaxies around Bright Stars: A New Strategy for Imaging at the Diffraction Limit
This paper presents a new strategy for observing faint galaxies withhigh-order natural guide star systems. We have imaged five high Galacticlatitude fields within the isoplanatic patch of bright stars (8.5mag
| Radial velocities. Measurements of 2800 B2-F5 stars for HIPPARCOS
Radial velocities have been determined for a sample of 2930 B2-F5 stars,95% observed by the Hipparcos satellite in the north hemisphere and 80%without reliable radial velocity up to now. Observations were obtainedat the Observatoire de Haute Provence with a dispersion of 80Ä,mm(-1) with the aim of studying stellar and galactic dynamics.Radial velocities have been measured by correlation with templates ofthe same spectral class. The mean obtained precision is 3.0 km s(-1)with three observations. A new MK spectral classification is estimatedfor all stars. Based on observations made at the Haute ProvenceObservatory, France and on data from The Hipparcos Catalogue, ESA.Tables 4, 5 and 6 are only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr or viahttp://cdsweb.u-strasbg.fr/Abstract.htm
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Gözlemler ve gökölçümü verileri
| Takýmyýldýz: | Koc |
| Sað Açýklýk: | 02h28m48.10s |
| Yükselim: | +23°52'13.9" |
| Görünürdeki Parlaklýk: | 8.447 |
| Uzaklýk: | 401.606 parsek |
| özdevim Sað Açýklýk: | -8.4 |
| özdevim Yükselim: | -1.6 |
| B-T magnitude: | 8.612 |
| V-T magnitude: | 8.461 |
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