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As the first result of spectroscopic monitoring of WR46 (HD 104994, WN3p) in 1991, a preliminary radial-velocity curve is presented with P = 6.8 hr, confirming the binary nature suggested from photometry.
We collected photometric data of WR 103 (HD 164270, WC9), both in the Walraven system and in the Strömgren system. Figure 1 presents one intense monitoring run, performed in 1990 by R. van Ojik. We suggest to describe the light-curve as a saw-tooth with a time-scale of roughly 0.5 day. Alhough we confirm a cyclic light-variation of the object with an amplitude of ∼ 0.05 mag, our data do not support the period of P = 0.88 d found by Isserstedt & Moffat (1981) (see also Moffat et al. 1986; Balona et al. 1989).
We studied the short-period (P ≈ 6–8 hr) binary system WR46 using simultaneous photometry and spectroscopy. We show that the long-term photometric variation is accompanied by changes in the equivalent width of the He II Λ5411 emission line and by an apparent period decrease on the rising branch. Furthermore, the brightening of the object is repeating.
The field of variable star research has become so broad and the amount of research to be reported on has grown so rapidly that it is a vain hope that a report of this kind, in a very limited space, could cover the whole field of research and could mention all the papers that have been published in the last three years. It is only hoped that this report presents the significant results achieved in the field of the most important aspects of variable star research. Some important subjects (e.g. cataclysmic variables) relevant to the variable star research are reviewed in the reports of other commissions. This is a consequence of the fact that the research has become very complex and the phenomena producing light variability belong to the field of interest of other commissions, too.
The field of variable-star research is so broad that no report of this nature could possibly mention all the papers that have appeared in the last three years. It is hoped, however, that the reviews below include the most important work and identify the most significant trends. This report comprises ten sections on as many different research topics, each written by a different member of Commission 27. In addition there are (in Section 12) three short reports about ongoing activities of the commission. The commission president is very grateful to the authors of the individual contributions who have worked so conscientously.
VBLUW photometry of high precision of two S Dor type stars AG Car (in a quiescent stage) and HR Car was made in 1987 and 1988. Both stars show visual micro variations with amplitudes of 0m.1 – 0m.2 with time scales – 10d for AG Car and – 20d for HR Car.
A number of yellow and red super- and hypergiants show phenomena that are similar to those shown by Luminous Blue Variables. The LBV phenomenon may not be restricted to the blue part of the Hertzsprung-Russell diagram and the conventional name ‘S Dor variables’ seems more appropriate.
Since 2000 the performance of Corus cold mill 21 has improved
substantially. The Overall Equipment Effectiveness (OEE) increased
from 33% to 43% and productivity has increased from a level of 1.4
million tonnes in 1999 to nearly 2.0 million tonnes presently. A suitable
balance in the triangle of technology, installation and people has
proven to be the key prerequisite in this performance increase. The
key knowledge areas to operate, maintain and improve the mill are
now all available within the production organization.
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