RR Lyrae Stars
The dome’s open and I’m observing GSC 2504-566, an RR Lyrae star. This, as I mentioned previously, is a pulsating variable star. Thus, it is swelling up and getting bigger and then shrinking smaller again in a regular, periodic pattern. This tells us a lot. We can estimate the mass of the star from the period. The change in color tells us about the change in temperature. We can also estimate (and measure, using spectroscopy) the change in radius as it changes size. These stars are all roughly the same intrinsic luminosity, as well, so they act as “standard candles” that aid in the rather vexing problem of measuring distances in the universe. RR Lyrae are very common but there are still some interesting unanswered questions about them.
I’m doing alternating exposures in two bandpasses, V (which is green) and Ic (which is near-infrared).
Sunday, April 23, 2006