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Rise/eclipse dur.

PINX74
Affiliation
American Association of Variable Star Observers (AAVSO)
Tue, 03/03/2015 - 09:10

 

hi all!

I need your help. I have two problems:
1) I am beginner (it  can be perform laugh)
2) I'm French and not confortable in English. (for citizenship, I can not do anything wink, and for my level, it's difficult...)

who can explain what represents the percentage "RISE / ECLIPSE DURATION" in the VSX form.

for example the star AE UMA it is 16%

 

I thought it was the realy duration of an eclipse between two peaks, but AE UMA light curve seems parabolic ....

thank you for your help.

Sebastian Otero
Affiliation
American Association of Variable Star Observers (AAVSO)
Tue, 03/03/2015 - 15:47
Eclipse and rise duration

Hi Jean-louis,

The eclipse/rise duration field has a different meaning depending on the star's type.

For eclipsing binaries of the Algol subtype (EA), the eclipse duration is the time spent in primary eclipse since first to last contact expressed as a percentage of the period.

For pulsating variables is the time spent from the time of minimum to the time of maximum expressed as a percentage of the period.
In this case it is used mostly for assymetric pulsators like RR Lyrae, cepheids or HADS (symmetric light curves have rise durations of 50%).

The example you quote (AE UMa) is a HADS so 16% means the light curve is assymetric with a rising branch much faster than the descending branch.

Best wishes,
Sebastian