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A Wide Area Survey for High-Redshift Massive Galaxies. II. Near-Infrared Spectroscopy of BzK-Selected Massive Star-Forming Galaxies
Results are presented from near-infrared spectroscopic observations of asample of BzK-selected, massive star-forming galaxies (sBzKs) at 1.5< z < 2.3 that were obtained with OHS/CISCO at the Subarutelescope and with SINFONI at the Very Large Telescope. Among the 28sBzKs observed, H? emission was detected in 14 objects, and for 11of them the [N II] ?6583 flux was also measured. Multiwavelengthphotometry was also used to derive stellar masses and extinctionparameters, whereas H? and [N II] emissions have allowed us toestimate star formation rates (SFRs), metallicities, ionizationmechanisms, and dynamical masses. In order to enforce agreement betweenSFRs from H? with those derived from rest-frame UV andmid-infrared, additional obscuration for the emission lines (thatoriginate in H II regions) was required compared to the extinctionderived from the slope of the UV continuum. We have also derived thestellar mass-metallicity relation, as well as the relation betweenstellar mass and specific SFR (SSFR), and compared them to the resultsin other studies. At a given stellar mass, the sBzKs appear to have beenalready enriched to metallicities close to those of local star-forminggalaxies of similar mass. The sBzKs presented here tend to have highermetallicities compared to those of UV-selected galaxies, indicating thatnear-infrared selected galaxies tend to be a chemically more evolvedpopulation. The sBzKs show SSFRs that are systematically higher, by upto ~2 orders of magnitude, compared to those of local galaxies of thesame mass. The empirical correlations between stellar mass andmetallicity, and stellar mass and SSFR are then compared with those ofevolutionary population synthesis models constructed either with thesimple closed-box assumption, or within an infall scenario. Within theassumptions that are built-in such models, it appears that a shorttimescale for the star formation (sime100 Myr) and large initial gasmass appear to be required if one wants to reproduce both relationssimultaneously.Based on data collected at the Subaru telescope, which is operated bythe National Astronomical Observatory of Japan (S04A-081, S05A-098), andon observations collected at the European Southern Observatory, Paranal,Chile (075.A-0439).
| FAUST observations of ultraviolet sources in the directions of NGC 4038-39 and 6752
Analysis of ultraviolet (UV) observations with the FAUST shuttle-bornetelescope toward the Antennae and NGC 6752 celestial regions resulted inthe detection of 46 and 221 candidate sources respectively, for asignal-to-noise ratio of 8. We discuss the source detection process andthe identification of UV sources with optical counterparts. Usingcorrelations with existing catalogues, we present reliableidentifications for approximately 60 per cent of the sources. We findthat most identified objects are B, A and F stars. The remainingidentified objects are galaxies, a white dwarf in a binary system, andtwo K-type stars. Nearly all of the remaining unidentified objects haveassigned optical counterparts but, lacking additional information, wegive these only as best estimates. With help from new diagnosticdiagrams, we suggest that these unclassified objects are main-sequence(or giant) stars within the local spiral arm or halo; or other hotevolved objects within the local spiral arm. We discuss the nature ofthe objects found and compare our results with those predicted fromspectral and Galactic models.
| A catalog of far-ultraviolet point sources detected with the fast FAUST Telescope on ATLAS-1
We list the photometric measurements of point sources made by the FarUltraviolet Space Telescope (FAUST) when it flew on the ATLAS-1 spaceshuttle mission. The list contains 4698 Galactic and extragalacticobjects detected in 22 wide-field images of the sky. At the locationssurveyed, this catalog reaches a limiting magnitude approximately afactor of 10 fainter than the previous UV all-sky survey, TDl. Thecatalog limit is approximately 1 x 10-14 ergs A sq cm/s,although it is not complete to this level. We list for each object theposition, FUV flux, the error in flux, and where possible anidentification from catalogs of nearby stars and galaxies. Thesecatalogs include the Michigan HD (MHD) and HD, SAO, the HIPPARCOS InputCatalog, the Position and Proper Motion Catalog, the TD1 Catalog, theMcCook and Sion Catalog of white dwarfs, and the RC3 Catalog ofGalaxies. We identify 2239 FAUST sources with objects in the stellarcatalogs and 172 with galaxies in the RC3 catalog. We estimate thenumber of sources with incorrect identifications to be less than 2%.
| Radial velocities of faint stars from objective prism plates
A simple method by which the approximate radial velocity of a star maybe obtained from objective prism plates is described in detail. Themethod has been used to derive the velocities of 41 faint stars, most ofwhich have metal-weak spectra and are shown to be high-velocity objects.It is shown that this method may be generalized so that the radialvelocities for all measurable stars on an objective prism plate can beobtained.
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| Сазвежђа: | Гавран |
| Ректацензија: | 12h09m32.04s |
| Deклинација: | -21°03'11.3" |
| Apparent магнитуда: | 7.99 |
| Даљина: | 154.56 parsecs |
| Proper motion RA: | 6.3 |
| Proper motion Dec: | -11.6 |
| B-T magnitude: | 8.195 |
| V-T magnitude: | 8.007 |
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