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Evolved GK stars near the sun. I - The old disk population
A sample of nearly two thousand GK giants with intermediate band, (R,I),DDO and Geneva photometry has been assembled. Astrometric data is alsoavailable for most of the stars. The some 800 members of the old diskpopulation in the sample yield accurate luminosities (from two sources),reddening values and chemical abundances from calibrations of thephotometric parameters. Less than one percent of the objects arepeculiar in the sense that the flux distribution is abnormal. Thepeculiarity is signaled by strong CH (and Ba II) and weak CH. The CH+stars are all spectroscopic binaries, probably with white dwarfcompanions, whereas the CH- stars are not. A broad absorption band,centered near 3500 A, is found in the CH+ stars whereas the CH- objectshave a broad emission feature in the same region. The intensity of theseabsorptions and emissions are independent of the intensity of abnormalspectral features. Ten percent of the old disk sample have a heavyelement abundance from one and a half to three times the solar value.The distribution of the heavy element abundances is nearly a normal onewith a peak near solar abundance and ranges three times to one sixthsolar. The distribution of the (U, V) velocities is independent of theheavy element abundance and does not appear to be random. Ten percent ofthe old disk stars show a CN anomaly, equally divided between CN strongand CN weak. Several stars of individual astrometric or astrophysicalimportance are isolated.
| Large and kinematically unbiased samples of G- and K-type stars. V - Evolved stars in the selected areas at + 15-deg declination
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1990PASP..102..242E&db_key=AST
| The radial velocity curve and peculiar TiO distribution of the red secondary star in Z Chamaeleontis
Data on the secondary star of Z Cha have been obtained with the CCDspectrograph of the CTIO 4-m telescope, giving a spectral type of M5.5for this star. The absolute absorption strength of TiO is shown to beweak on the side of the star that faces the white dwarf and theaccretion disk. Masses of 0.84 + or - 0.09 and 0.125 + or - 0.014 solarmasses are found for the white dwarf and the secondary star,respectively. It is noted that standard assumptions must be relaxed inorder to provide a consistent model for Z Cha. The observed splitting ofdouble-peaked emission lines implies a velocity that is 70 + or - 10percent of the Keplerian velocity at the outer edge of the accretiondisk.
| Accuracy of two-dimensional spectral classes derived through DDO photometry.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1977AJ.....82..832Y&db_key=AST
| A sample of old-disk-population red giants.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1976PASP...88..426E&db_key=AST
| Photoelectric radial velocities. IV. 528 7 to 10 mag stars in the +15degree selected areas.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1971MNRAS.155....1G&db_key=AST
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Dades d'Observació i Astrometria
| Constel·lació: | Cancer |
| Ascensió Recta: | 08h10m00.50s |
| Declinació: | +12°50'32.5" |
| Magnitud Aparent: | 8.072 |
| Moviment propi RA: | -24 |
| Moviment propi Dec: | -0.5 |
| B-T magnitude: | 9.549 |
| V-T magnitude: | 8.194 |
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