Colour Photometry in Astrophysics
Presenter(s): Stan Walker
Affiliation(s): Auckland Astronomical Society
Session details: Saturday, 2016-03-26 01:00:00, LT101
Abstract
Colour photometry as a simple alternative to spectra was introduced with the development of filtered photoelectric photometry in the 1950s. It is cruder in some ways and relies heavily upon empirical relationships. However, it is quicker and simpler than spectra and can reach much fainter magnitudes. This presentation initially explains what it is and how it has been used, with a variety of practical examples. It then discusses observational possibilities in a range of astrophysical aspects of stars which show evolutionary or other changes in their light and colour curves.
Biography
Stan’s astronomy began about 1960 and by 1965 he was observing variable stars visually. Attempts to monitor flare stars that way led to a project which saw a joint Auckland Observatory-University of Auckland project to build and use a photoelectric photometer. Commissioned in 1968, this was used until 1990 in a wide variety of projects, but mainly CVs and LPVs which are the stars he is most interested in. Until the mid 1980s they carried out the most effective photometry, to the faintest magnitudes, in New Zealand from the centre of NZ’s largest city!
Stan collaborated with Brian Marino and others in these projects, resulting in a good number of largely observational papers. Many highlights, but perhaps the best was the making of the first UBV measures of SN1987A and detemining from the colour changes on the second night that it was, indeed, a supernova.
A Chartered Accountant by profession, he is also a member of the Auckland Astronomical Society, Royal Astronomical Society, a fellow of the RASNZ and a member of Astronomical Photometry & Polarimetry, Binary & Multiple Star Systems, Pulsating Stars Commissions of the International Astronomical Union since 1970. Stan is currently the Director of Variable Stars South.
His observing these days is limited. Stan’s observatory is located at Waiharara (34.97S, 173.2E, 30M ASL) above the farm office.