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FAQ
I am not sure which kind of variable star is this one ...
Most likely we are not, either. Just mark your best guess. If other people will make different choices, we will know that this is a variable star whose type is not very well determined.
You are cheating! You show the very same points repeated twice!
Yes we are cheating, in a sense, but for a very good reason. Our measurements are spread over about 6 years, one or two per night, at most. With variables like RR Lyrae, having periods of half a day, the real light curve (brightness versus time goes by) would have a shape impossible to recognize. This is why we need to look at “phased” light curves. Curves show phase (or time for any period cycle) on the x-axis. With this method we can fold the points, originally spread over 6 years, all within one variation cycle (period). Then the curve takes a recognizable shape. We repeat this twice for clarity, otherwise it is hard to recognize features close to the edges of the graph. Of course, if the estimated period is wrong, the phase is wrong too, and the light curve is meaningless. Luckily enough, estimating periods is not the hardest thing in this game.
This variable could be an RR Lyrae/Cepheid or a Mira, but I am not sure because their example light curves are so similar
Look at the periods. Miras have periods significantly longer (more than 100 days as in the left-hand panel) compared to RR Lyrae and Cepheids (right-hand panel). Also, Miras have a total brightness variation typically larger than 0.6 in the y-axis, and small error bars. Then, if the brightness variation is large, and the periods are very long, it is most likely a Mira.
I have read that RR Lyrae and Cepheids are very different kind of variables. How come you don’t ask us to tell them apart?
RR Lyrae and Cepheids are indeed different kind of variables: very old and poor in metals the former, young and rich in metals the latter. They have similar light curves, but they can be easily distinguished according to their period by us.
How can I know how many variable stars I have already classified?
Click on your username, at the top-right corner, and select "HOME". There you will see how many objects you have classified in total (on any project). If you click on "My recent projects" you will see how many classifications you did in each Zooniverse project you worked on (it is the number on the top-right corner of the project's logo).
You can also see your recent classifications by clicking on "RECENTS" in the top menu.
According to the tutorial, each graph displays two period cycles. However in some cases I see four of them, and the minima are not different. Why is that?
In cases like this, you are most likely seen a genuine binary with two very similar minima for a period cycle. Since we show the period cycles repeated twice, there are four minima in the figure.