Variable Stars

Despite Aristotle's cosmology of static perfection, the inconstancy of the heavens has produced a lot of the good stuff. From Galileo's discovery of the changing pattern of sunspots on the face of the sun, to Hubble's first measurements of the expansion of the universe using Cepheid variable stars, astronomy in the time-domain has increased our knowledge tremendously. The scientific impact of this science and its ability to inspire incredible projects can hardly be overstated. The Hubble Space Telescope was built with the measurement of Cepheid Variable stars in mind (the HST Key Project) and plans are currently underway to build a telescope that will image the entire visible sky every three nights (LSST). Through the improving technology of observational astronomy we must realize that the term variable star is redundant. Almost all stars are variable at observable levels; in fact, it's the constant stars that are the unusual ones

I study stars which brighten and dim over months and years, stars that are commonly called Long Period Variables (LPVs). For the technically inclined you can read all about it in my latest paper. LPVs are always red giants, stars that have used up most of their fuel and are at the end of their lives. When you try to figure out the period of their variability they often seem to be varying in two or more frequencies at once (like the sound from pressing a button on a land-line phone). I'm using MACHO Project data combined with infrared magnitudes from 2MASS to investigate the lives of these stars and to figure out how all this relates to mass loss.

The Large Magellanic Cloud Period-Luminosity diagram with 35,619 long period variables.