# Variation Rate

Affiliation
American Association of Variable Star Observers (AAVSO)
Wed, 06/19/2024 - 17:20

I'm curious if there is a chart or table available that shows the rate of change in magnitude of stars for various variable types?  I'm interested in relatively short time intervals - minutes.

Thanks for any suggestions,

Cliff

Affiliation
Variable Stars South (VSS)
Variation rate

Cliff,

I'm not aware of any such charts or tables.

I'm no mathematician, but could you obtain the values you need from the first derivatives of the functions describing the relevant parts of the light curves of interest?

Roy

Affiliation
American Association of Variable Star Observers (AAVSO)
Thanks for replying.  Yes, I…

Thanks for replying.  Yes, I am sure I can build it.  I just didn’t want to reinvent the wheel.  Doing it myself would probably be a good learning experience.

clear skies,

cliff

Affiliation
Variable Stars South (VSS)
First derivatives and rate of period change

The only experience I have is with O-C diagrams in which the period of the star is changing at a constant rate, and thus can be described by a quadratic function in the form:

y = ax2 + bx + c (ax2 is a times x squared)

y is the O-C value, x is the epoch or cycle number

The first derivative of the x squared term is 2a which is the rate of change of the period, in days/ cycle.

I suppose for your situation a similar process might be applied to a short segment of a light curve.

Roy

Affiliation
American Association of Variable Star Observers (AAVSO)
Interesting

Cliff, you got me thinking. So I compared an EW, W UMa with an EA, NU UMa.

The EW showed 0.8 magnitude/ hour

The EA showed 0.05 magnitude/ hour

The EW components are almost at contact distance and higher velocity.

I think it is natural but otherwise not informative beyond the orbital mechanics.

Fun to ponder though.

Ray