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Oxygen line formation in late-F through early-K disk/halo stars. Infrared O I triplet and [O I] lines
In order to investigate the formation of O I 7771-5 and [O I] 6300/6363lines, extensive non-LTE calculations for neutral atomic oxygen werecarried out for wide ranges of model atmosphere parameters, which areapplicable to early-K through late-F halo/disk stars of variousevolutionary stages.The formation of the triplet O I lines was found to be well described bythe classical two-level-atom scattering model, and the non-LTEcorrection is practically determined by the parameters of theline-transition itself without any significant relevance to the detailsof the oxygen atomic model. This simplifies the problem in the sensethat the non-LTE abundance correction is essentially determined only bythe line-strength (Wlambda ), if the atmospheric parametersof Teff, log g, and xi are given, without any explicitdependence of the metallicity; thus allowing a useful analytical formulawith tabulated numerical coefficients. On the other hand, ourcalculations lead to the robust conclusion that LTE is totally valid forthe forbidden [O I] lines.An extensive reanalysis of published equivalent-width data of O I 7771-5and [O I] 6300/6363 taken from various literature resulted in theconclusion that, while a reasonable consistency of O I and [O I]abundances was observed for disk stars (-1 <~ [Fe/H] <~ 0), theexistence of a systematic abundance discrepancy was confirmed between OI and [O I] lines in conspicuously metal-poor halo stars (-3 <~[Fe/H] <~ -1) without being removed by our non-LTE corrections, i.e.,the former being larger by ~ 0.3 dex at -3 <~ [Fe/H] <~ -2.An inspection of the parameter-dependence of this discordance indicatesthat the extent of the discrepancy tends to be comparatively lessenedfor higher Teff/log g stars, suggesting the preference ofdwarf (or subgiant) stars for studying the oxygen abundances ofmetal-poor stars.Tables 2, 5, and 7 are only available in electronic form, at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/402/343 and Table\ref{tab3} is only available in electronic form athttp://www.edpsciences.org
| The Tokyo PMC catalog 90-93: Catalog of positions of 6649 stars observed in 1990 through 1993 with Tokyo photoelectric meridian circle
The sixth annual catalog of the Tokyo Photoelectric Meridian Circle(PMC) is presented for 6649 stars which were observed at least two timesin January 1990 through March 1993. The mean positions of the starsobserved are given in the catalog at the corresponding mean epochs ofobservations of individual stars. The coordinates of the catalog arebased on the FK5 system, and referred to the equinox and equator ofJ2000.0. The mean local deviations of the observed positions from theFK5 catalog positions are constructed for the basic FK5 stars to comparewith those of the Tokyo PMC Catalog 89 and preliminary Hipparcos resultsof H30.
| Photoelectric Elements of the Eclipsing Binary XY Ceti
The absolute elements of the system XY Ceti have been obtained on thebasis of the spectroscopic elements given by Popper (1971) and thephotoelectric elements derived by us. The colours of the components havebeen obtained. Both components are found to lie fairly on the MainSequence. The primary component of the system, however, is slightly moreevolved as it shows a tendency to drift away from the Main Sequence. Thespectral classes now assigned are A5V (primary) and A7V (secondary). Thevalues of Roche constants indicate that the system is a detached one
| UVBY and H beta photometry of early-type stars in a region at high galactic latitude.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1973AJ.....78...47D&db_key=AST
| UBV photometry of early-type stars in two regions at high galactic latitudes
Not Available
| A Finding List of Stars of Spectral Type A7 and Earlier in Regions at High Galactic Latitudes. III. 4 HLF 4
An objective prism survey has been made of stars of spectral type A7 andearlier in a 45 square degree region in the 4 HLF 4 area (l^II =180°, b^II = -45°) as part of an investigation of galacticstructure perpendicular to the galactic plane. The survey reported herewas made with the 4° prism on the Michigan Curtis Schmidt telescopeat Cerro Tololo. A finding list containing positions and spectral typesfor 88 stars is presented with finding charts for the stars too faint tobe included in the Bonner Durchmusterung.
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תצפית ומידע אסטרומטרי
| קבוצת-כוכבים: | לויתן |
| התרוממות ימנית: | 03h01m51.26s |
| סירוב: | +03°08'17.0" |
| גודל גלוי: | 8.168 |
| מרחק: | 166.389 פארסק |
| תנועה נכונה: | 2.5 |
| תנועה נכונה: | 6.9 |
| B-T magnitude: | 8.298 |
| V-T magnitude: | 8.179 |
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