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The rapid photometric variability of some Ae/Be-star envelopes
The results of narrowband photometry of several Ae/Be stars of differenttypes are presented. The observations were performed with the CrimeanAstrophysical Observatory 70-cm AZT-8 telescope with a 5-channelphotoelectric spectrometer. Variability with a characteristic time ofseveral minutes to several days is found in the H-alpha and H-beta linesand in the region beyond the Balmer limit. Consideration is given tosome mechanisms which can explain this variability.
| Ultraviolet interstellar extinction toward NGC 6530 and the intrinsic energy distribution of 9 Sagittarii and HD 165052
The ultraviolet interstellar extinction curve is determined toward 12early B main-sequence stars and one O8 V star in NGC 6530. Theextinction is found to be uniform across the cluster. At shortwavelengths, the extinction curve of NGC 6530 falls below the averageGalactic curve by a full magnitude, indicating that the population ofsmall grains relative to larger grains is lower than normal. Longward of2830 A the curve is almost coincident with the mean Galactic curve. The2175 A feature is narrower than the average. The derived extinctioncurve is used to deredden the observed fluxes of two early O-type starsin NGC 6530:9 Sgr and HD 165052. The intrinsic continua are compared tomodel atmospheres in the region 1200-8200 A. The LTE, line-blanketedmodels of Kurucz (1979) fit the observations better than the non-LTE,unblanketed models of Mihalas (1972) suggesting that line-blanketingeffects are more important than the non-LTE effects in the atmospheresof these stars. The temperatures of the models that best fit theobservations are lower than the Zanstra temperatures and thetemperatures estimated from the strengths of the He I and He II lines,by 10,000 to 20,000 K.
| Parallax and photographic orbital analysis of the close visual binaries Kuiper 84 and Furuhjelm 54.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1975AJ.....80..831L&db_key=AST
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Gözlemler ve gökölçümü verileri
| Takýmyýldýz: | Kartal |
| Sað Açýklýk: | 20h03m07.59s |
| Yükselim: | +07°15'15.5" |
| Görünürdeki Parlaklýk: | 9.499 |
| özdevim Sað Açýklýk: | -0.1 |
| özdevim Yükselim: | -6.5 |
| B-T magnitude: | 9.508 |
| V-T magnitude: | 9.5 |
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