Here is what has me excited. In a new paper in Astronomy and Astrophysics (which my Uni doesn’t get) with Pierre Kervella as lead author,Â¬â€ the distance to a Cepheid variable has finally been accurately measured in a method so simple I can’t believe it wasn’t done before. The binocular-bright Cepheid RS Pup is embedded in a nebula. As it’s light varies, it causes the dust and gas to also vary in brightness. By measuring how long after the star varies in brightness the blob of gas and dust varies in brightness, it is possible to tell how far apart the star and blob are located (sort of like measuring the distance between two cities based on how long it takes to drive between them going 100 km/hr). The next step is to measure the angle on the sky between the two. This gives us one angle and one side on a triangle. Everything else is than calculatable – including the distance from us to them.
Beautiful. Clean. Simple. I wish I knew why no one did this before. (Hopefully that’s addressed in the paper.)
The other thing the press release doesn’t do is tell me if these new results significantly changed our understanding of our place in space. Cepheid variable stars are one of the standardÂ¬â€ candles used to measure the distances to other galaxies and to calibrate the supernovae distance scale. If it turns out that we misplaced the Cepheids it will rescale things a bit. We shouldn’t be off by more than a few percent (we have some not totally accurate ways to measure distances today with bad parallax measurements), but still… It will be interesting to know how close we got by averaging a whole bunch of imperfect measurements.
Once I get my hands on the paper, I’ll let you know.