(cba:news) ES Ceti

Joe Patterson jop at astro.columbia.edu
Tue Aug 23 05:27:29 EDT 2016


Dear CBAers,

Cetus is rolling back into the morning sky, and we need one more season 
to complete our study of the period changes of ES Ceti.  This is the 
(moderately) famous AM CVn star with a 10-minute orbital period, and a 
waveform showing an "eclipse" each orbit (anyway, a periodic dip).  It's 
perfect for people with short attention spans but large telescopes.

Actually, not all that large (it's 17th magnitude)... and not all that 
short either, since it takes many cycles to accurately measure the 
periodic 0.1 mag dip.  But it's really a CBA special.  And it's an ideal 
target for period study, because the binary is likely driven by 
gravitational radiation, which scales as a high power of the orbital 
frequency.  Our study through 2015 shows an obvious period change - we 
just need to nail the rate down with a very accurate point for 2016.

With Porb = 10 min, you don't need a long run, but should have ~10 
orbits to give an accurate nightly timing.  The waveform varies 
*slightly* from one orbit to the next, so some averaging is needed.

Save the Whales, of course... but not this particular one.

joe p

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