If you cruise through most amateur astronomy magazines, chances are you'll find very little space devoted to variable stars. These are stars that, for a wide variety of reasons, change in brightness. I don't mean just twinkling - most bright stars do that, and it's caused by the effects of our unsteady air. It has nothing to do with the stars themselves. Variable Stars are of many types. Sometimes their brightness changes gradually over days, weeks, or even months, but sometimes quite unexpectedly and rapidly. If we observe a variable star for long enough, we can make a graph of its light changes over whatever period we like. These graphs are called light-curves and the shape of a star's light curve can often tell us what type of variable we are dealing with. We determine the brightness, or magnitude of a variable star by comparing its brightness to other nearby stars - called, reasonably enough, "comparison stars" - whose own magnitudes have been accurately determined and which are (hopefully) normal stars that do not vary. In this regard, before you leave this page for pastures new, don't forget to read the note at the end of the page.
I have always been drawn to variable stars, and could never understand those people who didn't find them interesting, but it seems that a lot of folks are quite content to look at a little disc of light for ages at a time! Maybe I don't have the patience; but be that as it may, the various planetary probes, Space Telescopes and so on have meant that amateur observations of the planets are maybe not so scientifically valuable as they used to be. Of course, that does not necessarily diminish their fascination for those who like looking at them! (It's just not for me, that's all). Chacun à son goût!
My interest in the sky was originally what might be called 'artistic' or 'spiritual' rather than 'scientific' in its basis, but that does not mean to say that one cannot contribute to scientific knowledge or that one's artistic interest may not grow to include the scientific, each enriching the other. Indeed, the study of variable stars is one of the few fields in the whole scientific corpus in which the non-professional worker can make original contributions. So, below is a little directory of the types of stars I like looking at, or, if you really want to, you can have a look at a little potted biography of yours truly. The bad news is that it includes my picture (you can always turn off pictures, though, can't you?).
Mira stars; Big red throbbing things!
RV Tauri stars; Chaos in action
Dwarf Novae; The cutting edge
Nebular variables; Stellar tantrums*
R Coronae Borealis; Smoke in the Sky
Peculiar Stars; Weird and Wonderful
I hope you like the animated logos for the different types of variables! I had a lot of fun making them. They give some idea of the variety of variable stars, though of course they're not meant to be terribly scientifically accurate - or "real time", though there are some variables that change over very short amounts of time. These, however, are not detectable by visual observers, and that's what these pages concentrate on, 'cos... well, that's what I do. Try some of the other observers on my VarStarLynx blue button to get a broader view of just what impact amateur astronomers can make on the world of astrophysics, or to find out about how you can become a part of something bigger, or get advice, try visiting the sites of some organisations which promote the observation of variable stars (the red button).
* My special interest is in the field of Young Stellar Objects, variable stars associated with the birth of stars and planetary systems. I have dedicated a special, separate part of the site to these.
Within the pages above you will find some charts for previously unobserved variable stars which are not to my knowledge on the official observing programmes of the AAVSO or other similar societies. Therefore if you do observe these stars, please bear in mind this fact if you submit reports. A lot of reporting is done electronically these days, and the reporting program will not be able to find stars which are not on its database. The charts provided here are essentially for interest, though of course I hope that at some time in the not too distant future some of these stars may find their way into official observing routines.
The light-curves included in these pages were produced by the AAVSO. If you're new to Variable Stars or astronomy, you could do worse than visit their excellent site. It is worth pointing out, too, that these curves are only provisional and have not passed all the various selection criteria which would make them 'official'.
Okay, end of amazingly strict caution! It's fine now to go back to the top of the page again.
Michael Poxon / June 2005