Proposal #64

Mira stars are important objects (Willson and Marengo 2012). Their long periods and large amplitudes make them particularly suitable for amateurs, a group of observers that are not bound by the sometimes short-time scales that exist in the project-driven world of professional astronomy.

While there are thousands upon thousands of mira stars in the International Variable Star Index, for many of these, data on periods etc is scarce. The reason can be found in the history of variable star astronomy. Many of these objects were discovered during the large-scale photographic surveys, using blink comparators, that were pursued during the 20th century, but were later not followed up. To discover that a particular star is a mira variable was relatively easy, while producing high-quality data characterizing the objects with some level of reliability – period, magnitude at maxima and minima, the existence of ”humps” in the light curves, possible period changes – takes much longer time to pursue than the mere classification of a star as a mira.

Here, amateur observers can play a role producing data that is important for analysis, for example, of long-term period changes (Karlsson 2014). One example was the project ”50 forgotten miras”, pursued by the variable star group SAAF/V, that observed 50 not so well-known miras in order to increase the accuracy of our knowledge of these objects. Data was collected during several years and after further analysis, the entries on objects were updated in the VSX and discussed in a JAAVSO paper (Karlsson et al 2016).

Now, a new project along similar lines has been started, focusing on a group of 25 miras with sub-par data available, of which I am a part. The goal is to observe this group of less-observed miras for a number of years, in order to produce a better knowledge of these objects, along the lines of the earlier project on 50 forgotten miras. I hereby apply for time on the AAVSOnet to observe these 25 objects with a cadence of one observation in V per object every third week for three years.

Positions for the objects, entered below, are 2000.0. The minimum magnitude given below (16) are rough guesses, owing to the poor knowledge of these objects, whereas maximum magnitudes are somewhat better known.

References:

Karlsson, T. 2014. ”Long-term Secular Changes in the Period of Mira Stars”. Journal of the American Association of Variable Star Observers (JAAVSO) 42 (december): 280.
Karlsson, T., H. Bengtsson, T. Wikander, G. Holmberg, R. Wahlström, and C. Allen. 2016. ”50 forgotten Miras”. Journal of the American Association of Variable Star Observers (JAAVSO) 44 (december): 156.
Willson, L. A., and M. Marengo. 2012. ”Miras”. Journal of the American Association of Variable Star Observers (JAAVSO) 40 (juni): 516.