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HD 82858

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Doppler images from dual-site observations of southern rapidly rotating stars - II. Starspot patterns and differential rotation on Speedy Mic We have secured high spatial and temporal resolution spectra of therapidly rotating K dwarf Speedy Mic (HD 197890) at two sites and acommon epoch of observations. The 0.38-d axial rotation period and theV-band magnitude of 9.33 make it a difficult target for Doppler imaging.In order to obtain high signal-to-noise ratio profiles from 300-sexposures, we apply the technique of least-squares deconvolution to thelarge number of photospheric absorption lines available in each of ourspectra. This allows us to derive high-resolutionmaximum-entropy-regularized Doppler images of the stellar surface. Usingthese techniques, we also derive radial velocities and accurateprojected equatorial rotation velocities which are consistent to within~1kms-1. Our surface maps reveal one of the most heavilyspotted photospheres seen on a rapid rotator, with starspots occurringat all latitudes. At the time of observations, Speedy Mic had no strongpolar spot, but it shows spots concentrated in low- andintermediate-latitude bands. We attempt a differential rotationmeasurement, but lack of sufficient phase coverage allows determinationof only a lower limit of 59d for the time it takes the equatorialregions to lap the polar regions. We also find variations in the heavilyfilled-in Hα line which can be attributed to prominences passingin front of the stellar disc. Despite the rapid rotation, the appearanceof the same features on consecutive nights of observations shows theclouds to be stable on time-scales of at least a day.
Large and Kinematically Unbiased Samples of G- and K-Type Stars. III. Evolved Young Disk Stars in the Bright Star Sample Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1989PASP..101...54E&db_key=AST
Large and kinematically unbiased samples of G- and K-type stars. II - Observations of evolved stars in the Bright Star sample. III - Evolved young disk stars in the Bright Star sample Four color and RI observations were obtained for a large sample ofG-type and K-type stars in the Bright Star Catalogue. Data are firstpresented for 110 evolved stars. Photometry of evolved young diskpopulation stars have then been calibrated for luminosity, reddening,and metallicity on the basis of results for members of the Hyades andSirius superclusters. New DDO results are given for 120 stars.
Radial velocities of southern stars obtained with the photoelectric scanner CORAVEL. III - 790 late-type bright stars Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1985A&AS...59...15A&db_key=AST
Photoelectric determination of the colors of 286 stars south of declination -15 degrees. Not Available

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Osservazione e dati astrometrici

Costellazione:	Carena
Ascensione retta:	09^h31^m32.90^s
Declinazione:	-66Â°43'10.0"
Magnitudine apparente:	6.27
Distanza:	215.517 parsec
Moto proprio RA:	-19.1
Moto proprio Dec:	7.8
B-T magnitude:	8.018
V-T magnitude:	6.41

Cataloghi e designazioni:

Nomi esatti
HD 1989	HD 82858
TYCHO-2 2000	TYC 8953-1767-1
USNO-A2.0	USNO-A2 0225-06133551
BSC 1991	HR 3813
HIP	HIP 46737

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