J/PASP/105/36ivo://CDS.VizieR/J/PASP/105/36doi:10.26093/cds/vizier.61050036CDSSowell J.R.Wilson J.W.2025-09-09T14:11:42Z1998-03-02T20:30:11ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frmultiple-starsAll-sky Stroemgren photometric observations were obtained for 303 speckle binaries. Most stars were in the range of V = 5 to 8.These data, when combined with ratios of intensities from the CHARA speckle photometry program, will allow the determination of photometric indices for the individual components of binary stars with separations as small as 0.05 arcsec. These photometric indices will complement the stellar masses from the speckle interferometry observations to provide a much improved mass-luminosity relationship. Introduction: Binary stars play an important role in determining several key stellar physical parameters. The most fundamental quantity is stellar mass, which in order to be determined, requires knowledge of the orbital period and semi-major axis of the system. Unfortunately, the majority of visual binaries have orbital periods on the order of many decades, making complete cycles difficult to obtain during the lifetime of a single observer. The application of speckle interferometry has greatly improved the situation, for now hundreds of binary systems with periods on the order of ten years or less, are routinely observed, especially by astronomers at the Center for High Angular Resolution Astronomy (CHARA) at Georgia State University (McAlister & Hartkopf 1988). In conjunction with the appropriate spectroscopic data, precise ``visual'' orbits for these speckle binaries (Hartkopf et al 1989) will provide accurate masses for a wide range of spectral types.A second vital characteristic is intrinsic luminosity. This boundary condition is necessary for both stellar interior and evolutionary models. The CHARA speckle program recognized the need for luminosity information to complement astrometry observations. Accurate photometry, unlike astrometry, requires only a few observations of the system, unless a member is variable. Algorithms to extract luminosity ratios from the speckle data have been developed. Although the techniques are still limited (e.g., non-calibrated), previous ``speckle photometry'' results have been reported by Bagnuolo & Sowell (1988) and Bagnuolo & Hartkopf (1989) for Capella and by Dombrowski (1990) for several Hyades stars.The purpose of this observing program was to obtain accurate uvby photometry of a large set of speckle binaries discovered or frequently observed by CHARA. Knowing the integrated magnitude and the ratio of the luminosities at selected wavelengths provides sufficient information to solve for the intrinsic brightness and color of each component. When combined with the masses from the ongoing speckle astrometry program, these stars will be important calibrators of the mass--luminosity relationship. Visually unresolved binaries have usually been omitted from photometric programs. Most of the program stars are bright, and one would have expected them to be well observed. However, many were known to be visually unresolved or marginally resolved binaries; hence, these systems were often deleted from previous photometric programs. OBSERVATIONS The photoelectric observations were obtained during 1989 November 11 to 17 (by J.W.W.) and during 1991 April 24 to 30 (by J.R.S.). In both cases the Automated Filter Photometer was used on a 36-inch telescope at KPNO. The same 1P21 phototube and uvby filter set were used on the two runs, as was a 15 arcsec diaphragm. Standard deadtime corrections and sky subtraction procedures were applied (Henden & Kaitchuck 1982). The transformation equations are listed below: V(std) = _epsilon__y [(b-y)(std)] + _zeta__y + (y - _kappa_'_y X) (1) (b-y)(std) = _epsilon__b-y [ (b-y) - _kappa_' _b-y X ] + _zeta__b-y (2) m_1(std) = _epsilon__m_1 [ m_1 - _kappa_' _m_1 X ] + _zeta__m_1 (3) c_1(std) = _epsilon__c_1 [ c_1 - _kappa_' _c_1 X ] + _zeta__c_1 (4) The extinction, transformation, and zero point coefficients were determined nightly; these coefficients are listed in Table 1. The extinction, transformation, and zero point coefficients were determined nightly; these coefficients are listed in Table 1. Standard stars were taken from Perry et al (1987). Gronbech et al (1976) divided their standard stars (i.e., transformation equations) into two groups, with the division at b-y = 0.410. Olsen (1983) used three groups, for he subdivided the cooler standards into evolved and unevolved sets. We used only one set of standard stars and transformation equations for the following reason. The majority of our program speckle binaries were believed a priori to be unevolved B, A, F, or G stars. This assumption was due to the observational constraint that, in order to be resolved by speckle interferometry, the magnitude difference between the components cannot be too great. Figure 5 of McAlister & Hartkopf (1988) demonstrates that this difference is less than 2 mag for most of the speckle binaries. With the low number of either evolved or of cool stars expected to be in our sample, it was not felt that the time required for observations of multiple sets of standards was justified, especially since only the m_1 and c_1 indices would be affected. The current state of the CHARA speckle program dictated the faint limit to be on the order of V = 8. The bright limit was set by the photometer, which could not accurately measure brightnesses greater than V = 5. Consequently, the majority of the program binaries were of 5 and 6 mag. The highest priority stars were the ``McA'' binaries, discovered by H.A. McAlister using the KPNO photographic speckle camera during the late 1970's, and the ``CHARA'' binaries, discovered using the GSU/CHARA ICCD speckle camera, in operation since 1982. All binaries were discovered using the KPNO 4-m reflector (see McAlister & Hartkopf 1988). The stars have short periods of a few years and are being used to obtain complete orbital elements. Stroemgren filters were chosen for this photometric program, since these narrow bandpasses are routinely used for the CHARA speckle observations. The apparent Stroemgren magnitudes and indices obtained for 303 binary systems are presented in Table 2. Column 1 lists the HD number, column 2 gives either the HR, DM, or ADS number, and column 3 supplies the binary discoverer designation. Columns 4 and 5 give the right ascension and declination, respectively. Column 6 refers the reader to notes at the end of the table. Columns 7 through 15 give the magnitudes and the errors of the mean for the four Stroemgren indices, followed by the number of observations. The entries are in order of HD number. It should be noted that many of the program stars were known to be binary systems (e.g., spectroscopic) before the astrometric speckle observations were acquired. Consequently, many of the speckle binaries are actually in multiple systems. Unless the stellar system was a visual double separated by at least 10 arcsec, then the photometric observations presented here are for the entire multiple system. These cases can usually be determined from the binary designation given in column 3 of Table 2, whereas the inclusion or exclusion of wide components is referenced in column 6. Individual magnitudes can still be derived if the luminosity ratios (from speckle photometry) are obtained between all of the components. Analysis: The observations presented here were compared with the Stroemgren photometry by Olsen (1983). His program stars ranged from A5 to G0 in spectral type and were brighter than 8.3 mag. A total of 80 stars were common to both programs, and Figures 1 through 5 show the comparison of the four Stroemgren indices. Although a few stars have discrepant magnitudes in only one index, there were three stars, HD 173654, HD 168701, and HD 25555, that were consistently dissimilar in several of the indices. Although HD 173654 (HR 7059) has nearly a 0.3 mag difference in V, the cause is easily explained: Olsen's program excluded a nearby companion, whereas this program included it. However, the resolution of the differences (as much as 0.1 mag in V) for HD 168701 and HD 25555 (McA 13 Aa) are not apparent. These two stars are among the reddest ones observed by this program, so the lack of many red standard stars may be a factor in these two cases. Further observations of these two systems should provide the answer as to the cause for the differences. Individual magnitudes: As an example for deriving the magnitudes of individual components of an unresolved binary, we consider two Hyades stars whose orbital motions have been used by Dombrowski (1990) to find the cluster distance modulus. These stars, 51 Tau (HR 1331 = HD 27176 = McA 14 Aa) and Fin 342 Aa (HR 1391 = HD 27991), were assigned instrumental _Delta_y values of 0.72 and 0.29 mag, respectively (each having an assumed error of approximately +/-0.1 mag). >From Table 2, the composite V value for 51 Tau is 5.64 mag, and for Fin 342 Aa it is 6.46 mag. Magnitudes for the components are found as follows. In the equation below, one uses the difference of the magnitudes to solve for the flux ratio. _Delta_y = y_b - y_a = +2.5 log (F_a / F_b) (5) The subscripts ``a'' and ``b'' represent the brighter and fainter components, respectively. The contribution of the fainter component (in magnitudes) to the system's magnitude is described by equation 6. y__epsilon_= +2.5 log (1.000 + F_b F_a) (6) The magnitude of the brighter component is equal to the numerical sum of y__epsilon_ and the system's magnitude. The magnitude of the fainter star is then easily computed with the _Delta_ mag. Likewise, for brighter speckle systems, which could be observed in multiple bandpasses, photometric indices for each component can be derived. Table 3 lists the magnitudes and fluxes for 51 Tau and Fin 342 Aa. Ideally, one should use multiple bandpass data to derive photometric indices. But these two systems are members of the Hyades, an extensively studied cluster. Using the CM diagram from Hagen (1970) and making the assumption that all of the components are on the main sequence, one can derive (B-V)_o and then infer a spectral type. The brighter component of 51 Tau has (B-V)_o approximately equal to +0.4 mag, whereas the fainter component and the two stars of Fin 342 Aa are about +0.5 mag. Tables from Schmidt-Kaler (1982) suggest that the warmest star is F2-5; the others are roughly F8. J.R. Sowell wishes to thank R.S. Hyde (GTRI/EOL) for providing internal research funds. Likewise, J.W. Wilson acknowledges the support provided by H.A. McAlister through NSF Grant AST 8915324. The authors wish to thank H.A. McAlister, W.I. Hartkopf, and W.G. Bagnuolo for their help with the CHARA databases and for their comments on the manuscript. Also, the authors appreciate the improvements to the paper suggested by the anonymous referee. ================================================================================1993PASP..105...36Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/PASP/105/36CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/PASP/105/36https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/PASP/105/36http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/PASP/105/36https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/PASP/105/36https://vizier.iucaa.in/viz-bin/votable?-source=J/PASP/105/36http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/PASP/105/36GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/PASP/105/36/table2 (Observations)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/PASP/105/36/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/PASP/105/36/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/PASP/105/36/table2?GETtext/xml+votable180.050000true3.03333353.6238890.0055555555555555566/188 208 351 368 408 439 463 469 472 474 603 678 752 845 1016 1032 1088 1145 1348 1447 1734 1939 1983 2060 2125 2139 2399 2536 2731 2923 2940 2976 2984 3030 3066 3196 3198 3220 3274 3420 3616 3696 3723 3786 4073 4184 4207 4316 4358 4465 4516 4545 4548 4566 4670 4698 4797 4942 5013 5202 5209 5299 5310 5399 5476 5478 5501 5608 6106 6146-6147 6204 6242 6251 6722 7122 7139 7684 7695 7705 8508 8583 8610 8716 8735 8822 9032 9072 9096 9247 9458 9510 9525 9570 9607 9620 9683 9716 9875 10003 10058 10106 10445 10585 10943 11270 11339 11354 11430 11547 11951 12372 12509 12599 12634 12775 12964-12965 13025 13136 13507 13559 13566 13733 14086 14204 14375 14440 14525 14582 14636 14646 14653 14662 14786 14814 14821 14862 14881 14912 14996 15373 15428 15491 15577 15817 15906 16249 16678 16792 17137 17400 17513 17611 17754 17965 18003 18259 18508 18527 18542 18594 18636 18654 18660 18821 18881 18889 19027 19288 19417 19493 19525 19592 19923 19941 20278 20703 21175 21328 21351 21362 21394 21605 21631 21749 21788 21890 21937 21950 22070 22138 22189 22193 22333 22456 22513 22813 22935 23377 23410-23411 23423 23431 23444 23490 23515 23535-23536 23538-23539 23655 23862 23978 23997 24029 24159-24160 24192 24212 24372 24404 24496 25569 25571 25577 25684 25971 26141-26142 26147 26152 26195 26451 26478 26529 27096 27295 27409 27507 27520 27581 27591 27794 27893 27980 27984 28153 28173 28291 28513 28539 28593 29092 29116 29130 29149 29161 29333 29865 30115 30264 30269 30440 30458 30540 30640 30652 30697 30730 30910 31073 31154 31174 31284 31381 31507 31556 31642 31720 31812 31956 31998 32024 32043 32115 32145 32219 32383 32542 32549 32720 40783 40823 44478 44626 48094 48955 49101https://cdsarc.cds.unistra.fr/viz-bin/moc/J/PASP/105/36?format=asciiOpticaldefaultJ/PASP/105/36/table1Reduction CoefficientsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintDate(UT) (1)time.epochnullableDatePart[ab] See Note (1)meta.notecharkappa_y'(mean error on second line)stat.errorfloatkappa_b-y'(mean error on second line)stat.errorfloatkappa_m_1'(mean error on second line)stat.errorfloatkappa_c_1'(mean error on second line)stat.errorfloateps_y(mean error on second line)stat.errorfloateps_b-y(mean error on second line)stat.errorfloateps_m_1(mean error on second line)stat.errorfloateps_c_1(mean error on second line)stat.errorfloatzeta_y(mean error on second line)stat.errorfloatzeta_b-y(mean error on second line)stat.errorfloatzeta_m_1(mean error on second line)stat.errorfloatzeta_c_1(mean error on second line)stat.errorfloatJ/PASP/105/36/table2ObservationsHDHD designationmeta.idcharrecnoRecord number assigned by the VizieR team. 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