Tau4 Eridani

Template:Starbox begin Template:Starbox image Template:Starbox observe Template:Starbox character Template:Starbox astrometry Template:Starbox detail Template:Starbox catalog Template:Starbox reference Template:Starbox end Tau⁴ Eridani (τ⁴ Eridani, τ⁴ Eri) is a binary star system in the constellation Eridanus. It is visible to the naked eye with an apparent visual magnitude of 3.65. The distance to this star can be estimated using the parallax method, which yields a value of roughly 300 light years.

A visual band light curve for Tau⁴ Eridani, plotted from data published by Tabur et al. (2009)

This is an evolved red giant star currently on the asymptotic giant branch with a stellar classification of M3/4 III. It is a slow irregular variable star of type Lb, undergoing changes in magnitude over the range 3.57−3.72 with a periodicity of 23.8 d. The measured angular diameter of Tau⁴ Eridani is Template:Val. At its estimated distance, this yields a physical size of about 106 times the radius of the Sun. It shines with 1,537 times the luminosity of the Sun from an outer atmosphere at an effective temperature of 3,650 K.

This is most likely a binary star system. The companion is a magnitude 9.5 star at an angular separation of 5.7″ along a position angle of 291°, as of 2013. Template:Clear left