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IUE and stars with composite spectra
The IUE contribution to the study of binary stars is reviewed. The valueof ultraviolet spectra in defining the parameters of hot companions indouble systems is emphasized, as this is important for understanding ofthe masses, luminosities, and evolutionary states of both the componentstars. Cataclysmic variables; precataclysmics; symbiotic stars;atmospheric eclipsing binaries; Algols; cool and hot binaries; heavymetal stars; noninteractors; and Cepheids are discussed.
| UBV photometry of stars whose positions are accurately known.
Photometric indices V, B-V, and U-B were measured for about 560 stars ofthe AGK3R and NPZT catalogs between BD declinations 11 deg and 23 deg,using the 40-cm Cassegrain telescope of the Kvistaberg Observatory fromApril 1986 to May 1987. The observation procedure and the reductiontechnique were the same as in the earlier papers of this series by Oja(1984, 1985, 1986, and 1987). The mean errors were calculated from theinternal consistency of the data. The accuracy was found to be the sameas for the earlier parts of the survey.
| Spectroscopic segregation in binary systems
Binary systems displaying spectroscopic segregation, whereby linespectra of the two components overlap little or not at all inwavelength, account for a small subset of LUV objects (late-typeultraviolet). Optical and ultraviolet (IUE) spectra for one such system,HD 15351 + UV0225 + 13 (F4-5 V + sdO), are presented and a few relatedsystems described. The role of LUV objects in establishing an absoluteluminosity calibration for hot subdwarfs is emphasized, along with theirsignificance for stellar evolution. A search strategy for additionalspectroscopically segregated LUV objects is outlined.
| A survey of ultraviolet objects
An all-sky survey of ultraviolet objects is presented together with astatistical analysis that leads to the conclusion that there is asignificantly higher population of hot subdwarfs lying below themain-sequence than hitherto thought. The distribution of all ultravioletobjects, main sequence ultraviolet objects, and MK unclassifiedultraviolet objects are shown in galactic coordinates, and the absolutemagnitudes and color-color diagrams for these groups are presented.Scale heights are derived, giving values similar to planetary nebulaefor the hottest groups.
| Spectral classification of ultraviolet objects.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1978A&A....66L...9B&db_key=AST
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Gözlemler ve gökölçümü verileri
| Takýmyýldýz: | Koc |
| Sað Açýklýk: | 02h28m34.38s |
| Yükselim: | +13°52'35.4" |
| Görünürdeki Parlaklýk: | 8.619 |
| Uzaklýk: | 131.406 parsek |
| özdevim Sað Açýklýk: | 127.4 |
| özdevim Yükselim: | -46.1 |
| B-T magnitude: | 8.993 |
| V-T magnitude: | 8.65 |
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