Some Stars for September 2008

This article supplied by Stan Walker 17 August 2008

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We present a list of Mira variable stars which reach maximum brightness around September of this year. This is followed by a similar table of minima, but restricted to those stars with pe measures, usually VRI.

Mira Stars with Maxima during the next 3 months

Name Max Min Date      
Z Sco 9.2 13.4 Oct 25      
RZ Sco 8.8 12.2 Sep 21      
R Sco 10.4 15.0 Oct 17      
RR Oph 8.9 14.6 Sep 22      
V970 Oph 10.0 16.5 Oct 23      
RW Sco 9.6 15.0 Aug 1   pe  
S Oct 8.4 13.5 Sep 3      
VX Sgr 6.7 13.3 Jul 23      
R Pav 8.5 13.0 Oct 3      
RV Sgr 7.8 14.1 Dec 9      
R Aql 6.1 11.5 Dec 7      
RX Sgr 9.7 13.8 Nov 24      
S Sgr 10.2 14.8 Nov 6      
Z Sgr 8.6 16.0 Sep 4      
SW Sgr 10.0 13.4 Sep 16      
T Pav 8.0 13.8 Oct 13      
S Pav 7.2 9.3 Oct 9 SR   Blue star nearby
RS Aql 9.7 15.2 Oct 12      
W Cap 11.7 14.8 Sep 5      
RT Sgr 7.0 13.3 Aug 31      
R Mic 9.2 13.4 Sep 18      
U Cap 11.1 14.8 Oct 26      
RY Mic 9.7 13.8 Sep 9      
RR Cap 9.3 14.5 Sep 12      
V Cap 9.2 14.4 Sep 5      
Z Cap 9.5 14.0 Sep 15      
RR Aqr 9.5 13.9 Aug 24      
S Mic 9.0 13.8 Jul 8      
T Gru 8.6 11.5 Dec 2 Beat Period SG  
T Tuc 8.1 13.2 Sep 29      
V Phe 9.2 14.0 Nov 25      
R Aqr 6.5 10.3 Dec 22      
R Phe 8.0 14.1 Oct 13   pe  
V Cet 9.4 14.3 Aug 23   pe  
W Cet 7.6 14.4 Jul 16      

 

Mira Stars with Minima during the next 3 months

Name Max Min Date      
RT Sco 8.2 14.1 Aug 19      
W Pav 9.0 14.1 Sep 18      
T Sgr 8.0 12.6 Jan 5      
U Mic 8.8 14.0 Dec 21      
RU Cap 9.7 15.1 Nov 17      
R Mic 9.2 13.4 Dec 3      
Y Aqr 9.4 14.8 Nov 13      
R Gru 8.3 14.6 Dec 20      
R PsA 9.2 14.7 Sep 4      
T Gru 8.6 11.5 Sep 26      
R Tuc 9.8 15.1 Nov 22      

Mira stars tend to fall into three categories. Those with periods of 100-200 days where a secondary or beat period is often, perhaps usually, present. In many cases these are bright giants or supergiants of classes II and I. Those with periods of 200-400 days usually exhibit only single periods, but these periods alternate by 1-2% at intervals of several decades. Above 400 days we find those with changing periods or irregular light curves or even dual maxima and minima.

For time series photometry (TSP) to study period changes the observation of maxima is usually the most rewarding. But many have companions which are best detected using UBV photometry at minimum or merely examining these stars for flattened minima in the visual curves.

ASAS is heavily engaged in surveys of these stars at present but is only accurate over the range 7.0-12.0. It also strikes problems in crowded fields or where there are close field stars.

These predictions have been based upon the published dates in Circular 71 of the AAVSO. It is a little incomplete as regards southern stars.


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