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AAVSO Special Notice #168: Outburst of the symbiotic star Z Andromedae AAVSO HOME > publications > special notice

AAVSO Special Notice #168

Outburst of the symbiotic star Z Andromedae
September 25, 2009

The bright symbiotic star Z Andromedae is currently in outburst, having
risen from magnitude 10.3 to 9.3 over the past 30 days.  Rapid brightening
from approximately magnitude 10 to its current brightness occurred over the
past 10-15 days.  Both visual and instrumental photometry of Z And are
requested at this time.

Z And is an interacting binary system, where mass is transferred from an M
giant secondary star to a white dwarf primary, where it can undergo
thermonuclear burning on the white dwarf's surface.  The star undergoes
outbursts peaking at magnitude 8.5 to 9.5 and typically separated by about
630 days.  Larger outbursts occur much less frequently, with recurrence
times of 10-20 years.  Observations are requested at this time to assess
whether Z And will brighten significantly beyond the more common outburst
range.  Both visual observers and instrumental observers are strongly
encouraged to observe; instrumental observers are asked to make filtered
observations, with Johnson V being the primary filter, and Johnson B being
secondary; other filters may also be used if available, but V and B are

Z And is located at the following (J2000) coordinates:

RA: 23:33:40.00 ,  Dec: +48:49:06.0

Charts for Z And may be plotted with the AAVSO Variable Star Plotter:

Please submit all observations to the AAVSO using the name "Z AND".

This AAVSO Special Notice was prepared by M. Templeton.


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