(cba:news) AM CVn, clarified
jop at astro.columbia.edu
Tue Apr 30 06:27:11 EDT 2019
In my previous message, I said AM CVn is still a good target. Let ne
clarify! The main project for 2019 was to clarify the Pdot - the rate
of orbital period change, That part is done. There's a secondary goal:
to compare the slow phase wanderings of the positive (525 s) and
negative (1011 s) superhump. They wander on a timescale of months, so
they require *months* to compare their wanderings. I've always wondered
whether those wanderings are ~180 degrees out of phase - which one might
expect if they're both affected by small variations in disk radius.
Those variations must be quite tiny, but on the other hand, our
long-baseline measurements of period are very, very sensitive.
That side of the project still requires more data. However, the two
superhumps are easy to measure, not requiring all-night coverage (or
anything close). So AM CVn is still a good 2-hour target in the evening
sky; with a few observers on the case, that'll suffice for a phase
measurement of the superhumps (if continued for a few more weeks).
After that, it's HP Lib and CR Boo.
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