40 Arietis

40 Arietis is a probable binary star system in the northern constellation of Aries. 40 Arietis is the Flamsteed designation. Their combined apparent magnitude is 5.82, putting the system near the limit of naked eye visibility. Based upon an annual parallax shift of just $1.6$, it is 445 ly away from the Sun. At that distance, its brightness is diminished by 0.21 in magnitude from extinction caused by interstellar gas and dust.

This is a suspected spectroscopic binary with an angular separation of $19.74$ between the two components. The visible component is an evolved giant star with a stellar classification of K1 III. It is a suspected variable star of unknown type, and is around 2.6 billion years old with 1.6 times the mass of the Sun. With the supply of hydrogen at its core exhausted, the star has expanded to 20 times the Sun's radius. It is radiating 128 times the luminosity of the Sun from its swollen photosphere at an effective temperature of 4,473 K.