Times-Series Photometry & Spectroscopy of the Bright Blue Supergiant Rigel: Probing the Atmosphere and Interior of a SN II Progenitor

As the 7^th brightest star and the most luminous star in the solar neighborhood, Rigel (β Orionis) is a very intriguing object. This blue supergiant (B8 Iab; V-mag = +0.05-0.18-mag B-V = -0.03), at a distance (from Hipparcos) of ~240±35 pc has a <M_V> = -6.7 mag. The following physical properties were determined via spectroscopic, photometric, and interferometric studies: L/L_⊙ ≈ 66,000 K; T_eff ≈ 12,000 K; M/M_⊙ ≈ 17±3 R/R_⊙ ≈ 70; τ ≈ 3-10 Myr. Interestingly Rigel has similar physical properties with the 12^th mag blue supergiant progenitor of SN 1987A: Sanduleak -69° 202a. Thus Rigel (along with its co-asterism Betelgeuse) are likely to be the nearest progenitors of a Type II supernova. Such a nearby explosion would be V ≈ -11^th mag (similar to a quarter moon).