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The absolute magnitude of K0V stars from BT HIPPARCOS parallaxes
We investigate the properties of K0V stars with Hipparcos parallaxes andspectral types taken from the Michigan Spectral Survey. The sample of200 objects allows the empirical investigation of the magnitudeselection (Malmquist) bias, which appears clearly present. By selectingthose objects that are not affected by bias, we find a mean absolutemagnitude of M_V = 5.7, a downward revision from 5.9 mag.listed in Schmidt-Kaler (1982). Some objects have absolute magnitudesfar brighter than M_V = 5.7, and it is suggested that theseobjects (~ 20% of the total sample) are K0IV stars which may have beenmis-classified as a K0V star. The presence of the Malmquist bias in eventhis high quality sample suggests that no sample can be expected to bebias-free.
| A large, complete, volume-limited sample of G-type dwarfs. I. Completion of Stroemgren UVBY photometry
Four-colour photometry of potential dwarf stars of types G0 to K2,selected from the Michigan Spectral Catalogues (Vol. 1-3), has beencarried out. The results are presented in a catalogue containing 4247uvby observations of 3900 stars, all south of δ = -26deg. Theoverall internal rms errors of one observation (transformed to thestandard system) of a program star in the interval 8.5 < V < 10.5are 0.0044, 0.0021, 0.0039, and 0.0059, respectively, in V, b-y, m_1_ ,and c_1_. The purpose of the catalogue, combined with earliercatalogues, is to allow selection of a large, complete, volume-limitedsample of G- and K-type dwarfs, investigate their metallicitydistribution, and compare it to predictions of various models ofgalactic chemical evolution. Future papers in this series will discussthese subjects.
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Gözlemler ve gökölçümü verileri
| Takýmyýldýz: | Yontar |
| Sað Açýklýk: | 23h19m31.05s |
| Yükselim: | -26°27'10.0" |
| Görünürdeki Parlaklýk: | 9 |
| özdevim Sað Açýklýk: | 5.1 |
| özdevim Yükselim: | -11.8 |
| B-T magnitude: | 10.626 |
| V-T magnitude: | 9.135 |
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