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An Einstein Observatory SAO-based catalog of B-type stars
About 4000 X-ray images obtained with the Einstein Observatory are usedto measure the 0.16-4.0 keV emission from 1545 B-type SAO stars fallingin the about 10 percent of the sky surveyed with the IPC. Seventy-fourdetected X-ray sources with B-type stars are identified, and it isestimated that no more than 15 can be misidentified. Upper limits to theX-ray emission of the remaining stars are presented. In addition tosummarizing the X-ray measurements and giving other relevant opticaldata, the present extensive catalog discusses the reduction process andanalyzes selection effects associated with both SAO catalog completenessand IPC target selection procedures. It is concluded that X-rayemission, at the level of Lx not less than 10 exp 30 ergs/s, is quitecommon in B stars of early spectral types (B0-B3), regardless ofluminosity class, but that emission, at the same level, becomes lesscommon, or nonexistent, in later B-type stars.
| Color excesses of classical cepheids. I
The color excesses of eleven cepheids have been determined with the aidof photometry of field stars found in the proximity of the variables. Acomparison of the color excesses with previous color-excess results isgiven. Four cepheids: RT Aur, DT Cyg, Zeta Gem, and T Vul, haverelatively small and well-established reddening values. These fourstars, along with Alpha UMi, can serve as standards to calibratereddening-free indices with intrinsic color indices such as (b-y) or(B-V).
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Группы:
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Наблюдательные данные и астрометрия
| Созвездие: | Орёл |
| Прямое восхождение: | 19h50m36.75s |
| Склонение: | +00°43'28.2" |
| Видимая звёздная величина: | 8.899 |
| Собственное движение RA: | 0 |
| Собственное движение Dec: | -5.3 |
| B-T magnitude: | 8.954 |
| V-T magnitude: | 8.904 |
Каталоги и обозначения:
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