Pi Eridani, Latinized from π Eridani, is a star in the constellation Eridanus. It has an

apparent visual magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's lig ...

of 4.40, which is bright enough to be seen on a dark, clear night. Based upon parallax measurements, it is located roughly 480 light years from the

Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...

. This is an

evolved Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation ...

red giant star with a stellar classification of M1 III, and is currently on the asymptotic giant branch. It is a

slow irregular variable A slow irregular variable (ascribed the GCVS types L, LB and LC) is a variable star that exhibit no or very poorly defined periodicity in their slowly changing light emissions. These stars have often been little-studied, and once more is learnt a ...

type LB that can increase in magnitude up to 4.38. The measured

angular diameter The angular diameter, angular size, apparent diameter, or apparent size is an angular distance describing how large a sphere or circle appears from a given point of view. In the vision sciences, it is called the visual angle, and in optics, it is ...

of this star is . At the estimated distance of Pi Eridani, this yields a physical size of about 77 times the

radius of the Sun Solar radius is a unit of distance used to express the size of stars in astronomy relative to the Sun. The solar radius is usually defined as the radius to the layer in the Sun's photosphere where the optical depth equals 2/3: :1\,R_ = 6.957\t ...

. It shines with 1,123 times the luminosity of the Sun from an outer atmosphere at an effective temperature of 3,841 K.

References

{{DEFAULTSORT:Pi Eridani M-type giants Asymptotic-giant-branch stars Slow irregular variables Eridanus (constellation) Eridani, Pi Durchmusterung objects Eridani, 26 023614 017593

1162 Year 1162 ( MCLXII) was a common year starting on Monday (link will display the full calendar) of the Julian calendar. Events By place Europe * March 6 – German forces, led by Emperor Frederick I (Barbarossa), capture Milan; ...