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HD 217990


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Interstellar polarization from observations of A and F stars in high and intermediate galactic latitudes, and from stars in the Mathewson and Ford polarization catalogue
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1986A&AS...64..487K&db_key=AST

The chemical evolution of the solar neighborhood. I - A bias-free reduction technique and data sample
The possible ways of measuring the age-metallicity relation for thegalactic disk in the neighborhood of the sun are discussed. It is shownthat the use of a field star sample chosen on the basis of effectivetemperature introduces a bias which results in a monotonic increase inthe metal abundance of the disk with time. However, if theage-metallicity relation for the disk can be shown to satisfy certaincriteria, the bias introduced in such a sample can be neglected: thegalactic disk apparently satisfies the criteria. It is concluded that asample analyzed through the use of uvby and H(beta) photometry inconjunction with a self-consistent set of theoretical isochronesprovides the least biased, most accurate estimate of the age-metallicityrelation for the disk.

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Osservazione e dati astrometrici

Costellazione:Tucano
Ascensione retta:23h05m27.13s
Declinazione:-58°53'57.5"
Magnitudine apparente:7.841
Distanza:148.588 parsec
Moto proprio RA:30.1
Moto proprio Dec:14.5
B-T magnitude:8.183
V-T magnitude:7.87

Cataloghi e designazioni:
Nomi esatti
HD 1989HD 217990
TYCHO-2 2000TYC 8830-31-1
USNO-A2.0USNO-A2 0300-37866814
HIPHIP 114019
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