Near Infrared Phase Lag of Mira Variable, R Carinae
Presenter(s): Anthony Dutton, Gregorie Bond and Julian West
Affiliation(s): Astronomical Association of Queensland
Session details: Sunday, 2012-04-07 23:30:00, TBA
Abstract
Near infrared (NIR) photometry in the J and H bands has been undertaken over a 4 year period on the oxygen rich Mira type variable star R Carinae. Comparison of near infrared photometry with visual observations and DSLR photometry reveals the NIR light curve is asymmetric with the star rising to maximum brightness at a slower rate than it falls, also the NIR maximum is broader with a lower amplitude than the visual maximum. The measured phase lag of 40 to 60 days between visual maximum the NIR maximum is at the lower limit of published data for other oxygen rich Mira stars. This presentation compares the J and H band photometry results with visual observations and DSLR photometry. Spectra measured throughout 2011 with a 0.3nm resolution spectrograph will be used to consider changes in spectral classification, temperature and metallic oxide absorptions. The photometry and spectroscopy will be used to examine possible causes of the phase lag such as absorption of visual wavelengths by Vanadium Oxide molecules that form in the star’s atmosphere.
Biography
Anthony Dutton and Gregorie Bond have been undertaking an Edward Corbould Research Fund project through the Astronomical Association of Queenslandon the near infrared photometric monitoring of bright southern variable stars since 2006. A retired telecommunications engineer, Julian West has been active in amateur astronomy for over 15 years, and has been involved in imaging from film to CCD and Digital SLR cameras. He is also an enthusiastic amateur telescope instrument maker, focusing on astronomical spectroscopy. He has developed several cost-effective high resolution spectrographs for amateur use that are capable of being constructed without the need for advanced workshop equipment. He has also developed a novel method for accurate wavelength calibration for spectrographs used in ‘slitless’ or imaging mode.