Variable Stars - R Aqr
Type ο (omicron) Ceti-type (Mira) variables Symbiotic variables of the Z Andromedae type Click for lightcurve ο (omicron) Ceti-type (Mira) variables are long- period variable giants with characteristic late- type emission spectra (Me, Ce, Se) and light amplitudes from 2.5 to 11 magnitudes in V. Their periodicity is well pronounced, and the periods lie in the range between 80 and 1,000 days. Infrared amplitudes are usually less than in the visible and may be <2.5 magnitudes For example, in the K band they usually do not exceed 0.9 magnitudes. Symbiotic variables of the Z Andromedae type. They are close binaries consisting of a hot star, a star of late type, and an extended envelope excited by the hot star's radiation. The combined brightness displays irregular variations with amplitudes up to 4 magnitudes in V. A very inhomogeneous group of objects. AAVSO Legacy Long Period Variable Programme AAVSO Alert Notice 589: R Aqr coverage needed for Chandra and HST observations 4 August 2017: Dr. Margarita Karovska (Harvard-Smithsonian Center for Astrophysics) has requested "visual, photometric, and spectroscopic observations of the symbiotic variable R Aqr in preparation for and in support of Chandra and HST observations currently scheduled for October 2017." Dr. Karovska continues: "R Aqr is the nearest symbiotic system at a distance of only about 200 pc. It contains a white dwarf accreting from a mass-losing Mira-type star with binary separation of about 20 AU. The aim of the multiwavelength observations of this fascinating object is to study the physical characteristics of this system and including the multi-scale components of the powerful jet, from the central binary region to the jet-circumbinary material interaction region and beyond. "AAVSO observations are requested in order to monitor the state of the system and correlate with the satellite observations. "Visual observations and CCD/PEP observations in the U, B, V, I, J, and H bands are requested." DSLR photometry is also welcome. "Optical spectroscopy, including in the Halpha, [OIII]5007A region is  also requested. "Also requested is high-speed photometry in U and B bands (a cadence of as low as a few seconds would be ideal, but a cadence of about a minute may also be all right) to reveal any possible high- speed variations in the central binary. "Weekly observations now through...November would be very much appreciated, with increased frequency of observations to twice a week..." beginning four weeks before the Chandra and HST observations and continuing at that frequency until the end of the campaign. "This [level of coverage] will provide solid optical data crucial to interpreting the satellite data." Observers will be notified when the exact times of the Chandra and HST observations have been set. Please begin observations twice a week in mid-September if the Chandra and HST observation times have not been announced by then.
Hills Observatory: 1 January 2013 to 14 August 2018