IW Andromedae is a Z Cam star!

This is not a newsbreak. Taichi Kato, Ryoko Ishioka and Makoto Uemura described this system as a Z Cam dwarf nova back in 2003, in the International Bulletin on Variable Stars (IBVS).

Based on 55 observations made over a period of about four months this team caught IW And in a standstill, which is the defining characteristic of Z Cam dwarf novae.

Light curve of IW And from Kato et al, 2003, IBVS 5376

Since the earliest days of the Z CamPaign http://arxiv.org/abs/1104.0967 I had noticed that the light curve of IW And was unlike that of any other system in the Z Cam candidate sample. It exhibited a quasi-periodic behavior whose light curve looked more like an eclipsing system than a dwarf nova.

This never before seen behavior led me to believe that perhaps we had discovered some new animal in the CV Zoo. "This doesn't look like a Z Cam light curve," I told myself. "We may have stumbled on to something important here!"

My ego quickly overruled the facts, and I have been hoping ever since that I had uncovered some unique, astrophysically interesting class of CVs. I convinced a lot of people to pay special attention to this system, hoping that my “discovery” would pan out.

Fortunately, the stars couldn’t care less about my ego, and IW Andromedae has once again gone into a prolonged standstill, as evidenced by the AAVSO light curve, confirming that it is indeed a member of the Z Cam class of dwarf novae.

 AAVSO light curve of IW And, 
clearly showing the standstill after an active period of outbursts and quiescence.

Welcome to the club, IW And. I still think you are special, and you will remain one of my favorite variable stars forever. 

As if to add to the lesson in humility, V513 Cas, my other "special case" appears to be in the early stages of a Z Cam standstill also!

A Z CamPaign update will be coming soon. In the meantime, thank you to all who have made this campaign a success and keep up the excellent coverage.

No comments: