7 research outputs found

    Photometric analysis of Magellanic Cloud R Coronae Borealis Stars in the recovery phase of their declines

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    This paper presents the initial results of a multi-site photometric programme to examine the extraordinary behaviour displayed by 18 R Coronae Borealis (RCB) stars in the Magellanic Clouds (MCs). RCB stars exhibit a unique variability whereby they undergo rapid declines of up to several magnitudes. These are thought to be caused by the formation of dust in the stellar environment which reduces the brightness. The monitoring programme comprised the collection of UBVRI photometric data using five telescopes located at three different southern hemisphere longitudes (Las Campanas Observatory in Chile, Mount Joun University Observatory in New Zealand, and the Southern African Large Telescope (SALT) in South Africa). Examination of the data acquired in the V and I filters resulted in the identification of a total of 18 RCB declines occurring in four stars. Construction of colour-magnitude diagrams (V vs V-I), during the recovery to maximum light were undertaken in order to study the unique colour behaviour associated with the RCB declines. The combined recovery slope for the four stars was determined to be 3.37+/-0.24, which is similar to the value of 3.1+/-0.1 calculated for galactic RCB stars (Skuljan et al. 2003). These results may imply that the nature of the dust (i.e. the particle size) is similar in both our Galaxy and the MCs.Comment: accepted for publication in the Publications of the Astronomical Society of Australi

    Coordinated observational campaigns for non-radially pulsating objects

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    International audienceIn recent years we have initiated and contributed to a number of campaigns to study non-radially pulsating objects. Our observing facility is the Mt John University Observatory 1.0 m telescope equipped with a high-efficiency and extremely stable echelle spectrograph, ideal for spectroscopic mode identification. Our current interests include ? Scuti star campaigns and a programme to study the non-radial pulsations in ? Dor stars. We are investigating several different methods of line profile analysis and spectroscopic mode identification of these targets. An overview of the programme, with specific examples, is presented
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