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Tue, 14 Feb 2017


Mira the Wonder Star visible with the naked eye


Tracie Heywood (SPA Variable Star Section Director) writes:

The variable star Mira (omicron Ceti) brightened rapidly during January and is now visible with the naked eye from reasonably dark observing sites. From less dark sites it should be easy to see in small binoculars.

Mira was one of the first variable stars to be recognised. Sometimes it shines as bright as the stars in the Plough, but most of the time it is far to faint to be seen without binoculars. This resulted in its name, which means 'Wonderful'. The interval between successive maximum brightnesses is about 11 months, and because it lies quite close to the Sun's path through the sky, there are times, such as in 2015, when its maximum brightness can't be observed.

Mira is currently closing in on its 2017 maximum, which is predicted to occur in late February.

The light curve below shows the brightness changes seen in recent years, as observed by SPA VSS members. Note the gap in observations each spring when Mira is near conjunction with the Sun.

Mira is located in a fairly bland area of the sky. Normally, I would recommend making use of the fact that the "V" of the Hyades points towards it. However, during mid February 2017, Venus and Mars act as better "pointers", as can be seen in the chart below.

More information about Mira can be found in  this guide , which also includes charts that label useful "comparison stars" with which the brightness of Mira can be compared.

According to the latest observations, Mira is currently at around magnitude 3.6.

The peak brightness of Mira varies from one cycle to the next. The brightest peak ever recorded reached magnitude 1.7, while fainter ones have been around three magnitudes below this. The average is magnitude 3.6.  Mira has already reached this brightness in 2017 and could yet go brighter.

Be aware, however, the Cetus is heading rapidly towards the evening twilight and Mira will be lost in the twilight by mid March.

 

Added by: Robin Scagell