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Observations of active-chromosphere stars - IV. Photometry and spectroscopy of CF Octantis (HD 196818) We present photometry and spectroscopy of the single, K-type,active-chromosphere star CF Octantis (=HD 196818), from 1982 to 1986.The photometric data show the 20-d rotation period seen previously, andalso demonstrate that the light curve is variable on time-scales of afew months, which we ascribe to variations in the properties ofstarspots. We postulate that a temporary dimming of minimum light seenin mid-1983 was a result of the appearance and later disappearance of arelatively small spot or spot group, which had a lifetime between 10 and24 months. The main spot appeared relatively stable during the intervalof our observations, with a lifetime of at least 3 years. Our radialvelocity data are consistent with the results of other work in that novariations above observational scatter are seen. Both the Ca K andHα emission are variable, with tentative evidence for the latterthat a lower emission level occurred near the phase of photometricmaximum, although the spectroscopic and photometric data were notcontemporaneous. The lithium abundance is found to be logN(Li)=0.45+/-0.15. The star may have evolved from a rapidly rotating A-Fmain-sequence star.
| Ca II H and K Filter Photometry on the UVBY System. II. The Catalog of Observations Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995AJ....109.2828T&db_key=AST
| Photoelectric radial velocities. V. 69 southern HR stars. Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1972MNRAS.155..449G&db_key=AST
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Группы:
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Наблюдательные данные и астрометрия
Созвездие: | Водолей |
Прямое восхождение: | 21h16m39.60s |
Склонение: | -01°36'28.0" |
Видимая звёздная величина: | 6.48 |
Расстояние: | 259.067 парсек |
Собственное движение RA: | 22.9 |
Собственное движение Dec: | -14.4 |
B-T magnitude: | 7.713 |
V-T magnitude: | 6.587 |
Каталоги и обозначения:
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