HD 137509

In 1973, W. P. Bidelman and D. J. MacConnell found this to be a peculiar A star of the silicon type. During a reclassification of the spectra of southern stars in 1975, A. P. Cowley and N. Houk noted the strength of hydrogen lines and weakness of helium are more typical of a class near B9. It shows a luminosity above the main sequence, which is common for a peculiar A star. The stellar atmosphere appears deficient in helium, but shows a rich variety of metallic lines. However, there are no lines of manganese or mercury, so it's not a Hg–Mn Ap star. HD 137509 is now classified as B9p (SiCrFe) or B8 He wk SiCrFe, matching a late-type, helium-weak Bp star with overabundances of silicon, chromium, and iron.

This star was found to be photometrically variable by L. O. Lodén and A. Sundman in 1989, and a variable spectrum was noted by H. Pedersen in 1979. It has one of the strongest magnetic fields recorded for a chemically peculiar star, measured at around 29 kG, and shows a strong quadrupolar component. Both variances of the star allow its rotation period to be precisely measured. It is classified as a Alpha² Canum Venaticorum variable. The star is about 124 million years old with 3.4 times the mass of the Sun and 2.8 times the Sun's radius. On average it is radiating ~123 times the luminosity of the Sun from its photosphere at an effective temperature of 13,100 K.