January Country Victoria Meeting
Syllabus Speaker Dr Tom Richards on the subject:
A Variable Passion
The January ASV Meeting was again dedicated to the ASV Country Members. Special week-end functions on 12 and 13 January concluded on Saturday with a guided tour through the Melbourne Observatory, the ASV Library, a display of Sun Spotting and an open air dinner in the observatory grounds. Some 40 members shared in a variety of delicious food. Even a dessert for the variable passion of those so inclined.
The evening General Meeting started with a Terminology Talk by Barry Adcock on the Astronomical Unit (the basis for all astronomical measurements), its definition and its evolution; then the syllabus talk A Variable Passion by Dr Tom Richards (a look into the nature of, and the technology used in making sense of, variable stars); and finally an introduction to comet McNaught and its expected prominency.
When Tom started to talk about the changing world of the amateur astronomer, how increasing sophistication of equipment tends to blur the distinction between the professional and the amateur astronomer, the thought occurred to me that there should be another category division of astronomers, beyond the amateur or professional status: a category of those who take their astronomy work serious and those who just dabble in it. It became immediately obvious that Dr Richards definitely belonged to the former, to those who are passionate about their astronomy, be it amateur of professional. His scientific approach to the subject of variable stars was a lesson in how to make use of every ounce (or every digital bit in this case) of observational data in making sense of what you see.
Tom’s ‘wild world of variable stars’ includes the wide range of: Interacting Binary Stars such as Supernovae Type 1 - Novae - Dwarf Novae and Eclipsing Binaries, as well as the Pulsating Stars such as Cepheids - Miras and Delta Scutis. All with sub-groups of their own and all with their own peculiarities affecting what we see and measure. Contrary to the ancients belief (Aristotle taught that the starry sky was eternally invariable) all stars change during their lifetime. They get born they evolve and they die. But the term “Variable” is applied to variations noted during recorded history. The first star so recorded was Omicron Ceti, which in 1642 was named Mira (Latin for Wonderful) by Johannes Hevelius. Today there are over 40,000 confirmed variable stars in our own Galaxy alone. In a way the discovery of variable stars contributed to the revolution in astronomy at the time by challenging astronomers for explanations. They still do. Variable stars these days are generally analysed using photometry, spectrophotometry and spectroscopy. Observations of their brightness compared to non-variable stars of known magnitude can be used to establish a distinctive light curve. For regular variables the period of variation and its amplitude can be very well established; for many variable stars though these quantities may vary slowly over time, or even from one period to the next, in ways that are not yet fully understood.
To the many attributes Tom did list that favour amateur astronomers in their work I would like to add one more aspect, and that is serendipity. Serendipity favours an open mind, and amateurs by sheer numbers have an edge over professionals. Although Tom did not call it by that name, but when he showed us how he happened to, in his use of reference and comparison stars in charting a known object=s brightness fluctuations, discover a new variable, it was a classical example of a serendipitous discovery. Tom recognised that the strange resulting waveform must of necessity include a second variable: his comparison star was also a variable.
The vote of thanks for an impressive show was given by Barry Adcock with the traditional present in an environmentally friendly paper carry-bag.
PS. Dr Tom Richards is the recipient of the prestigious Bernice Page Medal for his contributions to CCD photometry, His Woodridge Observatory is a private research facility in an outer hill suburb of Melbourne. Its primary mission is the photometric study of variable stars and minor planets.