Ψ2_Aurigae
Psi2 Aurigae
Star in the constellation Auriga
Psi2 Aurigae, Latinized from ψ2 Aurigae, is a star in the constellation Auriga. It is faintly visible to the naked eye with an apparent visual magnitude of 4.79.[2] Based upon parallax measurements, this star is approximately 420 light-years (130 parsecs) away from the Earth. At that distance, the brightness of the star is diminished by 0.07 in magnitude from extinction caused by interstellar gas and dust.[5]
Most studies categorized this as a K-type giant star with a stellar classification of K3 III.[3] However, the results of a study published in 2003 list it with a classification of K3 Iab:, which would instead suggest it is a supergiant star.[4][10] The measured angular diameter of this star, after correction for limb darkening, is 1.97 ± 0.02 mas.[11] At the estimated distance of this star,[1] this yields a physical size of about 27 times the radius of the Sun.[7] It is radiating 304[6] times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,410 K.[8]
It was also known to be part of a much bigger constellation named Telescopium Herschelii. It was also the constellation's second-brightest star before it was unrecognized by the International Astronomical Union (IAU).