Analysis of the light variations of the Wolf-Rayet star WR16

in Astronomy and Astrophysics. Supplement Series (1990), 84

This paper presents new data sets of Stromgren differential photometry observations of the Wolf-Rayet star WR16, collected at the ESO (La Silla, Chile). Results of detailed data analyses support previous ... [more ▼]

This paper presents new data sets of Stromgren differential photometry observations of the Wolf-Rayet star WR16, collected at the ESO (La Silla, Chile). Results of detailed data analyses support previous findings concerning the variability of WR16, with dominating power at frequencies below 1.5/d. The variations were found to be positively correlated on time lags up to about two days, a characteristic delay larger than the time of replacement of a typical WR star wind. A simple stochastic model is developed for the low frequency variability of the star, which is able to explain the available observations. [less ▲]

Service Observing at ESO - Photometry of Variable Stars

in Coordination of Observational Projects in Astronomy (1988)

A status report on the activities and achievements of the "Long-Term Photometry of Variables" project is given.

Instrumental effects and the Stroemgren photometric system

in Astronomy and Astrophysics. Supplement Series (1987), 71

The extent to which the use of different photometers can affect results on stellar color indices was investigated by simultaneously observing a sample of widely different stars with several uvby ... [more ▼]

The extent to which the use of different photometers can affect results on stellar color indices was investigated by simultaneously observing a sample of widely different stars with several uvby photometric systems available at the ESO, La Silla, Chile. In one instance, the ESO 50-cm telescope and the four-channel photometer at the Danish 50-cm telescope were used simultaneously. The reductions were performed separately on each data set, using a linear color transformation procedure. The results agree with theoretical investigations which showed that substantial errors can arise from the nonconformity of passbands. It is emphasized that it is necessary to use separate color transformations for various stellar types and classes and for different interstellar reddenings. [less ▲]

Photoelectric scans of comet Halley.

in Diversity and Similarity of Comets (1987, September 01)

The authors compare radial photometric scans of comet Halley obtained in April 1986 at the European Southern Observatory, La Silla, Chile, with theoretical profiles derived from Haser's model.

Long-term photometric campaign at ESO and the new eclipsing P Cygni star R 81 in the LMC

in The Messenger (1987), 47

The Long-term Photometry of Variables project is described. All measurements were carried out in the Stromgren uvby system and preference was given to differential measurements with two comparison stars ... [more ▼]

The Long-term Photometry of Variables project is described. All measurements were carried out in the Stromgren uvby system and preference was given to differential measurements with two comparison stars. Included in this photometry program was the study of R 81, the counterpart of P Cyg in the LMC. A variation period of 74.59 + or - 0.01 days was obtained for this eclipsing binary. [less ▲]

Pre- and postperihelion photometry of Comet Halley from several observatories

in ESLAB Symposium on the Exploration of Halley's Comet (1986, December 01)

Photoelectric observations of P/Halley were carried out during several weeks between 15 Sept. 1985 and 25 June 1986. All measurements were made using the standard IAU/IHW cometary filters. Large amplitude ... [more ▼]

Photoelectric observations of P/Halley were carried out during several weeks between 15 Sept. 1985 and 25 June 1986. All measurements were made using the standard IAU/IHW cometary filters. Large amplitude night-to-night changes over periods of several days superimposed on the general trend of slow brightness variation were seen. Smooth and irregular variations with a range up to 0.2 mag on time scales of several hours were observed. Present photometric scans of comet Halley through the various filters are presented. Successive integrations were made every 5 arc sec, radially from the center out to a distance of 5 arcmin, essentially along the sunward-antisunward direction and in the direction perpendicular to it. [less ▲]

BW Vulpeculae - A coordinated campaign of photoelectric photometry from thirteen observatories

in Astronomy and Astrophysics. Supplement Series (1986), 66

This paper contains the fully reduced observational data on the Beta Cep star BW Vul, which were obtained in the summer of 1982 during an international campaign at thirteen observatories in the northern ... [more ▼]

This paper contains the fully reduced observational data on the Beta Cep star BW Vul, which were obtained in the summer of 1982 during an international campaign at thirteen observatories in the northern hemisphere. Useful measurements were made during a total of 486 hours. All observations have been assigned proper weights and were binned in time intervals of 90 seconds. In this manner the observations were combined into single data points which resulted in about 6000 mean differential measurements. A preliminary ephemeris for 1982 is derived, and a mean lightcurve is given. The results indicate a fair degree of stability in the shape and in the amplitude of the lightcurve. Possible variations exist in the morphology of the stillstand phenomenon. [less ▲]

The international photometric observing campaign on BW Vul: first results.

in Theoretical Problems in Stellar Stability and Oscillations (1984)

Not Available

Photometric Variations of the B6 Star HR 3440

in Information Bulletin on Variable Stars (1977), 1373

Not Available