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A Variety of Variables – Part 2 – Mira Variables

15 Apr 2011, 21:20 UTC
A Variety of Variables – Part 2 – Mira Variables
(200 words excerpt, click title or image to see full post)

This is a continuation to my post A Variety of Variables – Part 1.
Mira Variables
Mira Credit: NASA, ESA, HST and Margarita Karovska
Named after the first pulsating variable star identified – Mira (Omicron Ceti). Mira variables behave in a similar way to Cepheid variables, with a cycle of pulsations that lead to peaks and troughs in their light curves.
Mira's Light Curve Credit: AAVSO
Whilst similar to the light curve of a Cepheid Variable it is clear that Mira has some irregularity in its pulsation cycles (Note the gaps in the light curve show the period of time Mira sat too close to the sun to obtain a measurement of its luminosity). I.e. the peaks and troughs do not line up properly, more accurately each pulsation has a different amplitude, such a variation in the amplitude of pulsation does not occur in a Cepheid and is also the reason that Mira variables are not used for gauging astronomical distances like their cousins – they are not standard enough for a reliable distance scale to be based around them.
Mira variables pulsation periods are also somewhat irregular with some being slightly longer or shorter than others. Mira’s own average ...

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