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Pulsating AGB star in the symbiotic nova PU Vulpeculae
Not Available
| Photometry of symbiotic stars - an international campaign.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1991CoSka..21..303H&db_key=AST
| 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.
| Spectral variation and the expanding envelope of PU Vulpeculae
The peculiar variable star PU Vul showed significant spectral changes in1982. The mean radial velocity of absorption lines changed from +30 km/sin May to -50 km/s in November. Strong emission lines with P Cygniprofile of H-alpha, Fe I, Fe II, Ca I, Ba II, Sc II, and La II weredetected on a high-dispersion spectrum taken in November, 1982. The meanradial velocity of the emission lines in the spectrum is about +30 km/s.The blue shift of the absorption lines and the emergence of the emissionlines suggest the presence of an expanding envelope. This objectprobably entered an active period in 1982. Some points of similaritybetween PU Vul and the peculiar F-type supergiant Rho Cas are pointedout.
| A magnitude limited stellar X-ray survey and the F star X-ray luminosity function
An X-ray survey has been conducted of stars brighter than visualmagnitude 8.5 that have serendipitously fallen into the fields of viewof the Imaging Proportional Counter of the Einstein Observatory. Thesurvey includes 227 separate 1 x 1 deg fields, containing 274 stars witha visual magnitude of no more than 8.5 and covering a wide range ofspectral types and luminosity classes. X-ray emission was detected from33 stars, and upper limits have been determined for the remainder of thesample. F type stars dominate the detected sample, and most of these areshown to be dwarfs. An X-ray luminosity function for dF stars has beendeduced, and reveals that the average 0.2-4.0 keV luminosity of thesestars is around 10 to the 29th erg/sec. Constraints have been placed onthe high luminosity tails and medians of the X-ray luminosity functionsfor other types of stars.
| Infrared observations of Kuwano's novalike object
Infrared observations made in April, 1979 of the nova-like objectdiscovered by Kuwano in Vulpecula are reported. Measurements in therange 1 to 5 microns were obtained with an infrared photometer adaptedto the Cassegrain focus of a 1-m telescope on April 13 and April 15,1979. Observations are shown to lie close to the energy distribution ofa black body at 3200 K, with an excess in the visible region. Such atemperature would correspond to a main sequence star of type M 2 or agiant of type M O, however, the V magnitude of the object suggests thatit lies above the main sequence. It is concluded that the nova-likeobject is probably related to the symbiotic stars, consisting of abinary containing a variable cool star which can expand to provoke masstransfer onto a normally faint compact companion.
| Photoelectric Observations of the Novalike Object in Vulpecula
Not Available
| A Search for Metal-Deficient Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970ApJS...22..117B&db_key=AST
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Gözlemler ve gökölçümü verileri
| Takýmyýldýz: | Tilkicik |
| Sað Açýklýk: | 20h21m01.08s |
| Yükselim: | +21°31'03.0" |
| Görünürdeki Parlaklýk: | 7.915 |
| Uzaklýk: | 350.877 parsek |
| özdevim Sað Açýklýk: | -7.7 |
| özdevim Yükselim: | -19.7 |
| B-T magnitude: | 10.002 |
| V-T magnitude: | 8.088 |
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