Spectroscopy
Spectroscopy is the analysis of electromagnetic radiation received from astronomical objects and is generally presented as a graph of radiation amplitude versus wavelength. Amateur spectroscopy is presently restricted to the visual range, for cost and technical reasons, but that is hardly a limitation as the interested observer will find no end of interesting objects and events to observe.
Participating in amateur spectroscopy allows you to determine most of the properties of the brighter astronomical objects, such as chemical composition, temperature, spectral class, rotational velocity, red/blue shift, and physical behaviour. Once you are reasonably skilled in recording and processing quality spectra the very rewarding, and real science, world of pro-am campaign collaboration is open to you, where you will be very welcome as professional astronomers desperately need your contributions to their research.
Given that nearly all our understanding of the known universe has been obtained through spectroscopic analysis it may appear surprising that very few amateurs have been involved, until recently. Until about 20 years ago the main limitation to amateur participation was the lack of and high cost of the instrumentation, very rudimentary software and a generally low level of knowledge and also fear of what is still perceived as a difficult subject … astrophysics. Thanks mainly to the efforts of a small number of skilled and dedicated French amateurs (the ARAS group, led by Christian Buil) the availability of economic quality instruments, powerful free software and online forums has resulted, since the mid-1990’s, in a fast-growing amateur involvement, initially in France and Germany but now also in the UK, USA and other countries. Until the last year or two it was possible to count the number of participating amateurs south of the equator on the fingers of one hand, but that is now changing and hopefully adding spectroscopy to the VSS list of tools and campaigns will accelerate the change.
Projects for spectroscopy
Note that like the DSLR area, this area of research within VSS is based around the technique of observing, rather than purely the nature of the objects being studied. Some of the projects below therefore overlap with the research areas that focus purely on specific types of variable stars.
V0454 Carinae spectroscopic and photometric campaign
Campaign Coordinator: Mark Blackford Professional Advisor: Ed Budding
Ed Budding and Roger Butland are currently investigating this relatively bright but neglected eclipsing binary (range 6.96 to 7.16 V Mag, period 0.980417d). They’ve measured radial velocities from high resolution spectra recorded with the HERCULES spectrometer on the 1m McLellan telescope on Mt John and proposed that V0454 Car is probably another quaternary system – not unlike QZ Car, but a bit less massive.
The RV curve of the close binary system (eclipsing pair) is well covered, and they can get a reasonably good picture of it from both its set of spectral lines. However, the third component shows unexpected short-term variations superposed on a much longer-term trend. They think that it is in a binary arrangement with a lower mass companion having a period of order a week or two. However, they don’t have enough information to form a very clear picture at the moment.