A new investigation of the variable stars in the globular cluster Messier 9.
Abstract
New observations from the southern hemisphere have been used to check the periods for the 11 RR Lyrae variables in and around the globular cluster Messier 9. The periods were determined previously with data from northern observatories where M9 can only be observed over a small range in hour angle. Three of the eleven published periods were found to be in error. As a result of this, the mean period of the RRc variables has been revised from 0d.279 to 0d.341, the mean period of the RRab variables has been revised from 0d.6l4 to 0d.621,and a star previously believed to be an RR Lyrae has been reclassified as a Population II Cepheid. One of the RRc variables may be a double-mode pulsator. Another variable was studied, but the data were not sufficient for determining its period.
- Publication:
-
The Astronomical Journal
- Pub Date:
- November 1984
- DOI:
- 10.1086/113675
- Bibcode:
- 1984AJ.....89.1707C
- Keywords:
-
- Astronomical Photography;
- Globular Clusters;
- Variable Stars;
- Light Curve;
- Ophiuchi Clouds;
- Southern Sky;
- Stellar Magnitude;
- Astronomy