Z Cam Stars in the Twenty-First Century
Mike Simonsen, David Boyd, Bill Goff, Tom Krajci, Kenneth Menzies, Sebastian Otero, Stefano Padovan, Gary Poyner, James Roe, Richard Sabo, George Sjoberg, Bart Staels, Rod Stubbings, John Toone, Patrick Wils
Z Cam stars are a small subset of dwarf novae that exhibit standstills in their light curves. Most modern literature and catalogs of cataclysmic variables quote the number of known Z Cams to be on the order of 30 or so systems. After a four-year observing campaign and an exhaustive examination of the data in the AAVSO International Database we have trimmed that number by a third. One of the reasons for the misclassification of some systems is the fact that the definition of what a Z Cam is has changed over the last 85 years to what it is today. This has caused many stars formerly assumed to be Z Cams or rumored to be Z Cams to be eliminated from the final list. In this paper we present the results of our investigation into 65 stars listed at one time or another in the literature as Z Cams or possible Z Cams.
ST Chamaeleontis and BP Coronae Australis: Two Southern Dwarf Novae Confirmed as Z Cam Stars
Mike Simonsen, Terry Bohlsen, Franz-Josef Hambsch, Rod Stubbings
Z Camelopardalis (Z Cam) stars are a subset of dwarf novae distinguished by the occurrence of standstills, periods of relative constant brightness one to one and a half magnitudes fainter than maximum brightness. As part of an ongoing observing campaign, the Z CamPaign, the authors focused attention on several Z Cam suspects in the southern hemisphere. Two stars, BP Coronae Australis and ST Chamaeleontis were found to exhibit standstill behavior in 2013, thus confirming them as Z Cam type systems. This adds two more bona fide members to the 19 confirmed Z Cams, bringing the total to 21.