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The deep photometric minimum of FG Sagittae in 1998 as a typical manifestation of the R CrB phase inthe post-AGB stellar evolution
We performed photometric BVRI observations of FG Sge during 47 nights inMay-October 1998. The star exhibited a sixth deep minimum after theonset of the R CrB phase in 1992. It was a double minimum, as that in1994; the star experienced a bluing on the descent to the first minimum,as reflected by B-V and, less dramatically, by V-R, and reddened on thedescent to the second minimum. As at the previous minima, the bluing ofthe star is attributable to the formation of small, light-scatteringdust grains. In contrast to the previous minima, the blue minimum wasout of phase with the pulsation minimum, while the maximum of the secondvariation occurred at the pulsation minimum. Spectroscopic observationswith resolution of about 5 A have revealed the appearance of emission inthe NaI doublet lines and the Swan bands in May and its enhancement asthe star faded. The NaI emission line had been visible until October1998, while the Swan bands were in absorption in the fall. We have foundevidence for self-reversal of the entire stellar spectrum on the descentto minimum light. The duration of the self-reversal phase increases withtime, which may be caused by an increase in the sizes of thecircumstellar gas envelope produced by the stellar wind. The behavior ofFG Sge at the 1998 minimum, as at the five previous minima, is typicalof the R CrB stars.
| UBV observations of FG Sagittae in 1994-1995.
Not Available
| The First Flare of the Yellow Symbiotic Star Lt-Delphini = HE:2-467
Not Available
| The Henry Draper Extension Charts: A catalogue of accurate positions, proper motions, magnitudes and spectral types of 86933 stars
The Henry Draper Extension Charts (HDEC), published in the form offinding charts, provide spectral classification for some 87000 starsmostly between 10th and 11th magnitude. This data, being highlyvaluable, as yet was practically unusable for modern computer-basedastronomy. An earlier pilot project (Roeser et al. 1991) demonstrated apossibility to convert this into a star catalogue, using measurements ofcartesian coordinates of stars on the charts and positions of theAstrographic Catalogue (AC) for subsequent identification. We presenthere a final HDEC catalogue comprising accurate positions, propermotions, magnitudes and spectral classes for 86933 stars of the HenryDraper Extension Charts.
| Longterm Photometry of Variables at ESO - Part Two - the Second Data Catalogue 1986-1990
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1993A&AS..102...79S&db_key=AST
| Long-term photometry of variables at ESO. I - The first data catalogue (1982-1986)
This paper presents the catalog of photometric data in the Stromgrensystem obtained during the first four years (October 1982 - September1986) of the Long-Term Photometry of Variables (LTPV) program at ESO.The data are available in computer-readable form.
| Optical variability of PU Vulpeculae (Kuwano's nova-like object 1979) in 1979-1982
The variable star PU Vul, discovered by Kuwano in 1979, is characterizedon the basis of published IR and spectral observations and of UBVphotoelectric observations obtained with a Zeiss 60-cm reflector at theCrimean station of the Shternberg State Astronomical Institute during1979-1982. The data are presented in tables and graphs, and the deepfading observed in 1980-1981, after the 'outburst' of 1977-1979, isdescribed in detail. A binary-system model is proposed to explain theobserved behavior of the star, with discussion of the probable nature ofthe components, the evolution of the hot component and the gas shell, ofthe cool component, and the mechanism of the fading. It is alsoconsidered possible that PU Vul is a single star, but not one of FU Oritype.
| Period Increase in FG Sge
Not Available
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| Takýmyýldýz: | Okcuk |
| Sað Açýklýk: | 20h12m23.69s |
| Yükselim: | +20°04'28.8" |
| Görünürdeki Parlaklýk: | 8.695 |
| özdevim Sað Açýklýk: | 7.7 |
| özdevim Yükselim: | -3.8 |
| B-T magnitude: | 10.186 |
| V-T magnitude: | 8.819 |
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