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Photospheric and chromospheric activity in the late-type giant component of the evolved binary system HD 185510
UBV photometry and moderate resolution Hα spectrophotometry of theevolved binary system HD 185510 (sdB + K0 III), performed at CataniaAstrophysical Observatory, is presented and discussed. Thespectrophotometric data were collected in 1991, 1993, and 1994, whilethe photometric light curves were obtained in 1993, 1994 and 1995.>From the B and V photometry we determine a new photometricrotational period of 26(d) .23, confirming the asynchronous rotation ofthe cool giant component. The spectroscopic data confirm the vsin ivalue of 15 Km s(-1) measured by Fekel et al. (1993) and clearly reveala filled-in Hα line with appreciable variations. The excessemission of the line, observed at any orbital phase, is found to beanticorrelated with the V light curve and is primarily ascribed to thechromospheric activity on the cool star. The primary total eclipse isclearly visible in the U band, but undetectable in the V band. >Fromthe U observations we determined a total duration of the primary eclipse(from 1(st) to 4(rd) contact) of 1(d) .3883, with the ingress lastingonly 27 minutes. This new accurate monitoring and timing of the eclipseallowed us to improve the system solution which leads to R_C=8.8Rsun, T_C=4800K, R_H=0.11 Rsun, T_H=30000K for thecool and hot star respectively. The evolution of HD185510B is discussedalso in relation to the evolutionary status of HD 185510A and thesynchronization time scale. HD 185510B is probably a sdB near the zeroage extended horizontal branch, resulting from an enhanced mass loss inlate case B or case A mass exchange with a possible common envelopephase. A small amount (15-20%) of mass loss from the system which canaccount for the strong IR excess is suggested. The complete U B Vphotometric data set is available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| Observational studies of Cepheids. I - BVRI photometry of bright Cepheids
Over 1,000 differentially determined photoelectric BVRI observations andthe resulting light curves are presented for 24 bright Cepheidsaccessible from Northern Hemisphere observatories. The internalprecision of these data is shown to be better than + or - 0.01 mag, andthe accuracy of transformation to the Johnson BVRI system is nearly asgood.
| 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
| Colors of bright stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1954AJ.....59..228E&db_key=AST
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