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HD 202554


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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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Observation and Astrometry data

Constellation:みずがめ座
Right ascension:21h16m39.60s
Declination:-01°36'28.0"
Apparent magnitude:6.48
Distance:259.067 parsecs
Proper motion RA:22.9
Proper motion Dec:-14.4
B-T magnitude:7.713
V-T magnitude:6.587

Catalogs and designations:
Proper Names
HD 1989HD 202554
TYCHO-2 2000TYC 5194-478-1
USNO-A2.0USNO-A2 0825-19112688
BSC 1991HR 8132
HIPHIP 105046

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