目录
图像
上传图像
DSS Images Other Images
相关文章
Preliminary UVBY calibrations for G and K type dwarf stars
Four-color uvby photometry for several hundred late-type dwarf stars oftypes G, K and M is discussed. Mean values of photometric indices aregiven for MK spectral types between F8/G0V and M2V. Preliminary standardrelations between the four-color indices are derived. Based onparallaxes and results from high-dispersion spectroscopic analyses,calibrations of the observed indices in terms of Mv, log Te and Fe/Hhave been derived. The means errors are 0.29 mag, 0.009 dex, and 0.17dex, respectively. The calibrations are valid for class-V stars of allpopulations between G0 and M2. If extreme population-II dwarfs areexcluded, the mean error of the abundance calibration decreases to 0.13dex. Calibrations in terms of log g have been attempted,, but the lowaccuracy of the spectroscopic g determinations does not inspireconfidence in the results. The possible contribution of a'fourth-parameter' variation to the mean errors of the calibrations isbriefly discussed. This fourth parameter could be the intrinsic heliumabundance of the stars.
| Visual multiples. VII - MK classifications
Classifications are given for 865 components of visual multiples; theyshow no systematic differences from the MK system, and the random errorsare one subclass in type and two-thirds of a luminosity class. It isfound that at least 1% of the F-type IV and V stars are weak-lined, 32%of the A4-F1 IV and V stars are Am, and 5% of the A0-A3 IV and V starsare early-type Am. Attention is called to the large fraction (55%) ofthe A3-A9 III-V stars that are of luminosity classes III or IV, unlikethe percentage (16%) at neighboring types.
| Photographic measures of double stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970A&AS....1..357T&db_key=AST
|
提交文章
相关链接
提交链接
下列团体成员
|
观测天体数据
目录:
|
NEWS@SKY (Science&Space News)
