Many observers come to the AAVSO because they have decided they would like to contribute to science in some modest way. Two obvious ways to contribute to science are to discover something new, or to collect data that astronomers will actually use somewhere down the line to 'do science'.

Discovering comets, asteroids and new variable stars has been largely taken over by the multitude of surveys monitoring the sky daily. Many supernovae and novae are still discovered by amateurs, but the search requires investing hundreds of hours and special techniques to prove fruitful. Even then, not all of these objects will prove to be of great interest to professional astronomers or scientists.

Contributing observations that will become part of the data most often requested by professional astronomers is much easier. The only thing you need to know before putting together a program is 'which stars are astronomers interested in?'

You could poll all the professional astronomers you know, or look up the number of scientific papers written on all the variables you can think of, or ask AAVSO which stars they get data requests for most often, or you could simply observe what I call "Legacy Variable Stars".

Legacy Variables are stars that have been observed for decades and whose data can be plotted as light curves describing the behavior of the star over extended periods. Some of them have been observed for over one hundred years! In some cases, it has taken decades to demonstrate the behavior scientists are interested in studying. Legacy Stars will never go out of style, and it is precisely the long time line of visual observations that makes many of them important or of particular interest.

Many of these stars are among the first variable stars to be discovered, so they tend to be bright and have large enough amplitudes to be observed visually. Many of them are the prototypes of their particular class of variable stars, being the first to be explained or the first to be discovered as such. By contributing to the body of historical observations you are sustaining the legacy of these distinguished stars.

Mira: 02 19 20.79 -02 58 39.5 (2000)- Omicron Ceti, the first known periodic variable star, may be the star that most embodies the heart and spirit of the AAVSO. There are observations of Mira going back to the very first days of the AAVSO. There are historical observations going back to the 1600's. "Mira the Wonderful" as she is known, still manages to surprise and engage us in the 21st century. Changes in the UV spectrum of Mira indicate she is an active, evolving system and studies have been made from x-ray to radio wavelengths, utilizing Chandra, HST and the Very Large Array. As recently as 2005, Karovska et al reported the discovery of x-ray emissions from Mira. This prototypical long period variable (LPV) varies from 9th magnitude to naked eye visibility (2nd or 3rd magnitude) in around 331 days on average. At declination -02 she is observable in both hemispheres for extended periods each year. Observations as Mira approaches conjunction with the Sun and immediately after conjunction, as a morning object, are always highly valued.

Chi Cygni: 19 50 33.92 +32 54 50.6 (2000) Another LPV that attains naked eye brilliance is Chi Cygni. When at or near maximum, it becomes the fifth star delineating the body of the Swan from a dark sky site. Normally, Chi ranges from 5th magnitude to 13th magnitude, but has been observed as bright as 3rd magnitude and as faint as 14th magnitude. The average time from maximum to minimum and back is 408 days.

R Aql: 19 06 22.25 +08 13 48.0 (2000) Discovered in 1856, R Aquilae is a well-known Mira with an ever-decreasing period. It varies from 6th magnitude to 11th magnitude in a period that has shrunken from over 300 days to around 270 days currently. The fact that there are observations going back more than a hundred years has allowed this decrease in period to be discovered. There is some evidence that its amplitude may also be decreasing.

R Hya: 13 29 42.78 -23 16 52.8 (2000) R Hydrae has been observed regularly since its discovery in 1704. For decades its period remained constant at 495 days. From the 1770's to the 1950's the period slipped to 395 days and then suddenly stopped decreasing. The period has been steady at just under 400 days since the 1950's. Whatever process in the evolution of R Hya that began the period decrease has apparently stopped working.

T UMi: 13 34 40.50 +73 25 56.0 (2000) Discovered in 1902, this Mira was quite happy with a stable period of approximately 316 days until the 1960's. Then something, (and who knows, it was the 60's), put this poor star into a tailspin it has yet to recover from. The current period is around 240 days with no signs of leveling off. T Ursae Minoris is also noted as being one of a handful of stars with a hump in its light curve on the descending branch. Speculation as to what causes that phenomenon remains just that...speculation.

R Leo: 09 47 33.49 +11 25 43.6 (2000) Not all Miras exhibit period changes in the existing data. Some are well behaved and perform as expected within the framework of LPV behavior. R Leo is a fairly typical Mira with a period averaging 310 days, and a range of 5.8 to 10.0. Once you have observed R Leo you will never forget the small triangle it forms with two 9th magnitude comparison stars, almost due west of Regulus. Archival observations of R Leo go back 150 years or so, including AAVSO data from the early 1900's to the present. Some of the AAVSO's most prominent observers, including Leslie Peltier, observed R Leo for their entire careers.

R Cyg: 19 36 49.38 +50 11 59.5 (2000) Discovered by Norman Pogson in 1852, R Cygni has been a staple of the AAVSO observer diet since 1902. Even a cursory look at the light curve for R Cygni will show that it does not behave like typical Miras. The maxima of R Cyg alternate between bright and fainter maxima. There is a correlation between the brightness of maxima and the time interval from the previous one. Fainter maxima occur slightly behind schedule and bright maxima rush slightly ahead of the average period. Ranging from 6.2 to 14.6v, R Cygni can be a challenge to observe when it approaches minimum. There is a 4th magnitude star parked due west in the same high power field of view. Once you get over being dazzled by the beautiful star field and contrast in magnitudes, I think you'll see why it is an all-time favorite.

T Tau: 04 21 59.43 +19 32 06.4 (2000) On the other side of the spectrum, literally, we have the unpredictable, irregular variability of T Tauri. Discovered in 1852 by J. R. Hind, T Tau is the prototype of a class of low mass, young stars that are entering stellar adolescence after condensing from a cloud of dust and gas. Their uneven light variations may arise from activity in the stellar atmosphere or from instabilities or line of sight effects of the accretion disk associated with most of the stars of this type.

R CrB: 15 48 34.41 +28 09 24.3 (2000) Another of the prototypical stars of its class, R Coronae Borealis stars are supergiants with atmospheres lacking in hydrogen and rich in dusty carbon. They spend most of their time at maximum light and then without warning will begin to fade dramatically, up to 8 magnitudes! This precipitous drop in light output is usually very steep and quick, while recovery back to pre-fade output may be a long drawn out process with several recoveries and declines before making a long, slow, steady climb back to maximum. Astronomers are keen to study R CrBs because they represent a short-lived period in stellar evolution and they create copious amounts of dust. As such they are living laboratories for studying stellar evolution and dust production in stellar atmospheres. They are favorites for observers because of their complete unpredictability and large amplitude variations.

FG Sge: 20 11 56.06 +20 20 04.4 (2000) FG Sagittae is a unique star evolving in real time before our eyes. Described in one paper as the 'Born Again' star, FG Sge is embedded in an old planetary nebula. This dying central star apparently began re-shedding its atmosphere in a steady wind in 1992. It is cooling steadily, but maintains an essentially constant luminosity in infrared, while exhibiting irregular large amplitude variations visually. It may be related to or be a form of R CrB star, based on spectral studies and models indicating a hydrogen deficient atmosphere that would strengthen its link to the R CrB class.

Z And: 23 33 39.95 +48 49 05.9 (2000) Symbiotic systems are a mixed bag of binary stars involved in a close stellar dance inside a common nebular envelope. In the case of Z Andromedae we have a cool red giant and a compact, hot, dwarf star in orbit around each other, engulfed in nebulosity. The dwarf component is accreting mass via a stellar wind emanating from the red giant. During quiescence, Z Andromedae exhibits small, irregular variations. Every 10 to 20 years the system goes into a state of increased activity and brightens by three magnitudes. These large-scale outbursts are then typically followed by a string of smaller and smaller outbursts leading eventually back to quiescence. AAVSO observers have been monitoring this activity since 1917.

CH Cyg: 19 24 33.07 +50 14 29.1 (2000) Z Andromedae may be the prototype of the symbiotic class of stars, but CH Cygni may be the most observed and researched of the 150 or so known symbiotics. CH Cygni was first thought to be a red semi-regular with an M6-M7 spectrum, 90-100 day period, and a one-magnitude amplitude. This classification fit most of the facts until 1976 when the star erupted, then faded slightly before outbursting to magnitude 5.6! This "blue outburst" state lasted ten years. In 1986 the star faded by 2.5 magnitudes, and has been declining continuously, if erratically, ever since. Recently, CH Cyg has declined from 8th magnitude to approximately 10th magnitude, so it has gone from being a binocular object to requiring a small telescope to observe. Who knows, with continued monitoring we may again witness CH Cyg approach naked eye visibility.

The history of variable stars is full of interesting stories and stellar personalities. There are many more interesting Miras, R CrB and Symbiotic stars to observe that have a rich and varied history you can contribute to. In the next issue, we'll discuss some Legacy Cataclysmic Variables and their impact on the history and development of variable star research.