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CA II chromospheric emission and rotation of main sequence stars
Using published data on the Ca II K emission and rotation periods,correlations of these quantities with stellar parameters are analyzed inlate main sequence stars (F8-K5). The total power emission in the Ca IIK line, L(k), is found to follow (1) an exponential decay, with therotation period not dependent on the spectral type; (2) an exponentialdecay with the square root of the age; (3) a power law with the mass.Combining these dependences, it can be shown that the rotation perioddepends only on the mass and age of the stars. Implications on thestellar angular momentum evolution and on the magnetic field generationby dynamo mechanism are discussed.
| 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.
| Micrometer observations of double stars.8.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1975ApJS...29..315H&db_key=AST
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Osservazione e dati astrometrici
| Costellazione: | Cassiopea |
| Ascensione retta: | 00h17m44.82s |
| Declinazione: | +53°42'40.5" |
| Magnitudine apparente: | 7.85 |
| Distanza: | 10000000 parsec |
| Moto proprio RA: | -7.1 |
| Moto proprio Dec: | -3.1 |
| B-T magnitude: | 9.703 |
| V-T magnitude: | 8.003 |
Cataloghi e designazioni:
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