Cepheid Variable Stars 13, Cepheid stars vary in luminosity, Below we have a gra
ID: 2304696 • Letter: C
Question
Cepheid Variable Stars 13, Cepheid stars vary in luminosity, Below we have a graph of the apparent magnitude of a Cepheid star measured at a series of different days. Estimate the period of this Cephied: How much time does it take to go through a full cycle from bright to faint to bright again? takes this Cepheid l around 00 days to go throvgh a cycie origt to faint to bnan again) m 25 50 100 t (days) 1 Estimate the period of this Cepheid as well Cepheid 11 H takes this cepheid I around 35 days to g m through a f cycie. 25 s0 t (days)Explanation / Answer
What you have done is correct. It does not seem possible to get a better estimate from these plots.
In Cepheid I, starting from the maximum the luminousity decreases to the minimum in about 50 days and then it increases to the maximum in another 10 days approximately. Thereafter, this process repeats itself. So, the period is about 60 days. The confusion seems to be that the time it takes the luminosity to reach the minimum from maximum is not the same as the time to reach maximum from minimum, something which you see usually in periodic wave motion. However, period of a phenomenon is defined as the time after which the entire process is repeated over and over again. That is how the period of a Cephied is defined in the question.
The same is true for Cephied II.