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C.J. Butler, Research Astronomer next up previous contents
Next: J.E. Chambers, Research Astronomer Up: Research Previous: W.M. Napier, Senior Research   Contents

C.J. Butler, Research Astronomer

Dr John Butler has carried out activities in the following main areas:

1.
Observation and modelling of stellar flares: Two observing runs were undertaken (with D. Jevremovic) in 1998, as part of this project, one at the Observatoire de Haute Provence and the other with the William Herschel Telescope (WHT) on La Palma. The second run provided excellent high time-resolution optical spectrophotometry of a flare on the nearby active dwarf AD Leo, using a new drift-scan technique on a CCD. This is believed to be the first time that optical spectroscopy of a stellar flare has been obtained with a time-resolution better than 5 seconds.

A computer model, based on the MULTI model atmosphere code, has been used to fit the time profiles of the emission lines of hydrogen. Whilst broad overall agreement in the shape of the profiles is found, there are differences in their detailed behaviour and in the relative fluxes of the lines as modelled and observed. Further computations are in progress.

D. Jevremovic has continued to write up his thesis on the behaviour of the Balmer lines during stellar flares.

2.
Angular momentum of late-type cluster members: This programme (with Dr Armin Thiessen) has continued during the year with the preparation and submission of a paper containing the results obtained by Duncan Foster on the cluster Stock 2. An observing proposal for direct imaging time on the 40-inch Ritchey-Chrétien Telescope at Siding Spring Observatory received an award of a week in February 1999.

3.
COROT: Several applications were made for high-dispersion spectroscopic time on 2-metre class telescopes to assist our French colleagues in the selection of suitable targets for this very interesting space project on stellar seismology. No allocation of telescope time was made for 1998, but one week has been granted by the South African Astronomical Observatory (SAAO) in 1999 July.

4.
Climatology: A new PhD student, Enric Pallé Bagó, has started a project on the link between solar activity and cosmic rays on clouds and their possible influence on the Earth's mean temperature. A preliminary examination of the sunshine data for Armagh and three other Irish sites indicates (1) a gradual increase in the cloud factor since the late 19th century, probably as a result of the gradually increasing sea surface temperature associated with global warming. A correlation between the cloud factor and solar cycle length is apparent, but it is not yet clear if this represents a true physical connection.

5.
Meteorology: Collaboration with two external scientists has allowed some progress to be made in the compilation of those daily meteorological readings not previously entered on to computer. David Smyth of the University of Edinburgh has undertaken the verification of the daily rainfall data previously compiled and some additional data are currently being compiled by the Department of Agriculture Northern Ireland.

Professor Alistair Dawson of the University of Coventry is currently compiling the pressure data for a joint study on the pressure oscillation of the North Atlantic region over the past two centuries.

6.
Historical Studies: Several short biographies of previous members of staff at Armagh and Dunsink Observatories have been written.

7.
Conference: A three-day conference entitled `Solar and Stellar Activity: Similarities and Differences' was organised and held in Armagh in 1998 September to commemorate the life's work of Dr Brendan Byrne. It was attended by more than 60 scientists working in the field, many of whom had previously collaborated with Dr Byrne. The proceedings of the meeting were edited by C.J. Butler and J.G. Doyle and published by the Astronomical Society of the Pacific in their conference series.

8.
Administration: An Equal Opportunities policy was agreed and ratified by the MSF Union and the Observatory's Governing Board. Discussions on Grievance, Disciplinary Procedures and Conditions of Employment, continue.

9.
Further Research Plans: Future progress in the flare modelling project will require an additional Ph.D. student to take over from Darko Jevremovic (djc). If appointed he/she will be supervised jointly by John Butler and Gerry Doyle, with assistance from djc. We propose to use similar codes to those employed by djc to model solar flares as well as other stellar flares for which we already have data in hand. An XMM proposal for this project has been made.

The cluster programme is currently handicapped by the lack of success in obtaining additional spectroscopic time on telescopes of 2-4 metre class. Applications have been made for time on the Isaac Newton Telescope (INT) and the WHT which could allow further progress to be made. A switch in emphasis to wide-field imaging, if successful, promises to be a faster route to the end result than the previously attempted techniques involving high-resolution spectroscopy.

Examination of the influence of solar activity on cloudiness via the sunshine data will continue. Also it is planned to use the new data banks on cloud factors to make a thorough reappraisal of the effect of cosmic rays on cloud factors.


next up previous contents
Next: J.E. Chambers, Research Astronomer Up: Research Previous: W.M. Napier, Senior Research   Contents
ARM Starlink Manager Martin Murphy
1999-12-14