Document Actions

Polaris Monitoring Program

Monitoring Polaris - A Cepheid Variable Star

The image below shows a 25 arcminute x 17 arcminute field of view around Polaris. The image was taken using a Meade 8-inch f/10 telescopeand SBIG ST10 CCD camera. The images are taken and updated every 10 minutes. Click on the image for a larger view.

The telescope and camera are constantly active, even during inclement weather.

Polaris as a Variable Star

Polaris, the brighest star of the constellation Ursa Minoris is located at the tip of the handle of the Little Dipper. As the brightest of all Cepheid Variables, Polaris has been closely monitored in the past by many astronomers. Beginning after 1945, such astronomers noticed a rate of increase in Polaris' period as well as a rate of decrease in it's amplitude. It was then suggested in 1993 that Polaris would cease all pulsations within the next few years. Much to everyone's surprise, in 1998 astronomers noticed that Polaris did not cease pulsating - furthermore, it's amplitude decrease also stopped. With such unpredictable behavior, much is still left to be discoverd about Polaris. The amplitude of Polaris' variations is about 0.03 mag, and it's period is 3.97 days. Some astronomers suspect that we have been witnessing the evolution of Polaris as a Cepheid Variable: that this may be the process by which a Cepheid Variable evolves out of pulsating in it's first overtone to pulsating with its fundamental period - resulting in a more stable and stereotypical Cepheid Variable. This Project seeks to monitor Polaris continuously, providing live images of Polaris and a data base for continuous light curves of Polaris.

Methods

The telescope is a 0.25-m Meade and the camera is an SBIG ST10 CCD. The field of view is about 25 arcminutes x 17 arcminutes and the telescope tracks Poalris throughout the night. The physical size of the ST10 is 14.9 mm x 10 mm with 2184 x 1472 pixels, and pixel size of 6.8 microns. The scale with the Meade telescope is 0.70 arcsec/pixel.

The CCD camera control program takes 60 second exposures every 10 minutes and downloads the most recent exposure to this web page. The program runs autonomously. The Polaris telescope is located in the the North Star building of the optical ridge at PARI. The building is equipped with a 24 inch X 26 inch window and is of course oriented due North. Imaging begins when the window shutter is opened and ends when the shutter is closed. Another program monitors weather conditions and opens/closes the shutter at sunset and sunrise, respectively. The images are analyzed using IRAF, resulting in a continuous light curve of Polaris.

Some facts about Polaris
Aliases: