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An Observational Pursuit for Population III Stars in a Lyα Emitter at z = 6.33 through He II Emission
We present a very deep near-infrared spectroscopic observation of astrong Lyα emitter at z=6.33, SDF J132440.6+273607, which we usedto search for He II λ1640. This emission line is expected if thetarget hosts a significant number of Population III stars. Even after 42ks of integration with the Subaru/OHS spectrograph, no emission-linefeatures are detected in the J and H bands, which confirms that SDFJ132440.6+273607 is neither an active galactic nucleus nor a low-zemission-line object. We obtained a 2 σ upper limit of9.06×10-18 ergs s-1 cm-2 on theHe II λ1640 emission-line flux, which corresponds to a luminosityof 4.11×1042 ergs s-1. This upper limit onthe He II λ1640 luminosity implies that the upper limit on thePopulation III star formation rate is in the range 4.9-41.2Msolar yr-1 if Population III stars suffer no massloss and in the range 1.8-13.2 Msolar yr-1 ifstrong mass loss is present. The nondetection of He II in SDFJ132440.6+273607 at z=6.33 may thus disfavor weak feedback models forPopulation III stars.Based on data collected at the Subaru Telescope, which is operated bythe National Astronomical Observatory of Japan.
| A spectroscopic survey for lambda Bootis stars. II. The observational data
lambda Bootis stars comprise only a small number of all A-type stars andare characterized as nonmagnetic, Population i, late B to early F-typedwarfs which show significant underabundances of metals whereas thelight elements (C, N, O and S) are almost normal abundant compared tothe Sun. In the second paper on a spectroscopic survey for lambda Bootisstars, we present the spectral classifications of all program starsobserved. These stars were selected on the basis of their Strömgrenuvbybeta colors as lambda Bootis candidates. In total, 708 objects insix open clusters, the Orion OB1 association and the Galactic field wereclassified. In addition, 9 serendipity non-candidates in the vicinity ofour program stars as well as 15 Guide Star Catalogue stars were observedresulting in a total of 732 classified stars. The 15 objects from theGuide Star Catalogue are part of a program for the classification ofapparent variable stars from the Fine Guidance Sensors of the HubbleSpace Telescope. A grid of 105 MK standard as well as ``pathological''stars guarantees a precise classification. A comparison of our spectralclassification with the extensive work of Abt & Morrell(\cite{Abt95}) shows no significant differences. The derived types are0.23 +/- 0.09 (rms error per measurement) subclasses later and 0.30 +/-0.08 luminosity classes more luminous than those of Abt & Morrell(\cite{Abt95}) based on a sample of 160 objects in common. The estimatederrors of the means are +/- 0.1 subclasses. The characteristics of oursample are discussed in respect to the distribution on the sky, apparentvisual magnitudes and Strömgren uvbybeta colors. Based onobservations from the Observatoire de Haute-Provence, OsservatorioAstronomico di Padova-Asiago, Observatório do Pico dosDias-LNA/CNPq/MCT, Chews Ridge Observatory (MIRA) and University ofToronto Southern Observatory (Las Campanas).
| Vitesses radiales. Catalogue WEB: Wilson Evans Batten. Subtittle: Radial velocities: The Wilson-Evans-Batten catalogue.
We give a common version of the two catalogues of Mean Radial Velocitiesby Wilson (1963) and Evans (1978) to which we have added the catalogueof spectroscopic binary systems (Batten et al. 1989). For each star,when possible, we give: 1) an acronym to enter SIMBAD (Set ofIdentifications Measurements and Bibliography for Astronomical Data) ofthe CDS (Centre de Donnees Astronomiques de Strasbourg). 2) the numberHIC of the HIPPARCOS catalogue (Turon 1992). 3) the CCDM number(Catalogue des Composantes des etoiles Doubles et Multiples) byDommanget & Nys (1994). For the cluster stars, a precise study hasbeen done, on the identificator numbers. Numerous remarks point out theproblems we have had to deal with.
| The Case Low-Dispersion Northern Sky Survey. XIV - A-F stars in a region in southern Canes Venatici
Positions, estimated magnitudes, and finding charts are provided for 387A-F stars in an about 190 sq deg region in southern Canes Venatici. Thearea encompassed is between R.A. 12h00m and 14h10m and decl. +29 deg 00arcmin and +38 deg 30 arcmin (1950), excluding the region R.A. 12h00m to13h00m and decl. +29 deg to +34 deg, which was covered in a previouspaper. The A-F stars, whose blue magnitudes are within the range 8through 18 (median 14), were identified on low-dispersionobjective-prism plates taken with Case Western Reserve University'sBurrell Schmidt telescope at Kitt Peak.
| Further Studies of A-Stars and F-Stars in the Region of the North Galactic Pole - Part Four - a Catalogue of Uvbyr Photometry and Derived Quantities
Not Available
| Further Studies of A-Stars and F-Stars in the Region of the North Galactic Pole - Part Three - a Catalogue of Star Names and Positions
Not Available
| Four-color observations of early-type stars. Standards and secondary standards.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1973ApJ...179..855P&db_key=AST
| The galactic force law K(z
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1969AJ.....74..139P&db_key=AST
| Three-colour photometry of early-type stars near the galactic poles
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1963MNRAS.127...83W&db_key=AST
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| Takýmyýldýz: | Av Kopekleri |
| Sað Açýklýk: | 13h43m03.73s |
| Yükselim: | +29°40'43.5" |
| Görünürdeki Parlaklýk: | 9.052 |
| özdevim Sað Açýklýk: | 28.1 |
| özdevim Yükselim: | -21 |
| B-T magnitude: | 9.161 |
| V-T magnitude: | 9.061 |
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