TypeZ Andromedae typeClose binary systemClick for lightcurveSymbiotic variables of the Z Andromedae typeare 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 mag. in V. A very inhomogeneous group of objects.Close binary systems characterized by the presence of strong reflection (re-radiation) of the light of the hot star illuminating the surface of the cooler companion. Light curves are sinusoidal with the period equal to Porb, maximum brightness coinciding with the passage of the hot star in front of the companion. The eclipse may be absent. The range of light variation may reach 1 mag. in V. Example: KV Vel.AAVSO Alert 366: July 24, 2013 AAVSO observer Steve O'Connor (OCN; St. George's, Bermuda) reports a possible brightening episode of the symbiotic variable AS 270. O'Connor reports the star at V=12.75+/- 0.02 on 2013 July 24.535 (JD 2456498.035). The most recent prior observation reported to the AAVSO International Database (M. Linnolt, LMK; Ocean View, Hawaii, United States) had AS 270 at m(vis)=14.1 on 2013 July 13.390 (JD 2456486.890), suggesting a rise of more than one magnitude in less than two weeks. Nightly monitoring of this star is strongly encouraged during the current episode to determine whether an outburst is in progress.
Hills Observatory: 1 January 2013 to 2 December 2018