Pi

Its story

π Eridani burns red within the long celestial river of Eridanus, 481 light-years away. It is an asymptotic-branch M-type giant, swollen to more than sixty solar radii and cooled to about 3,880 K. Its brightness shifts slowly, with no fixed pattern —astronomers call it a slow irregular variable— as if breathing with the distracted cadence of an old star about to shed its outer layers.