1 Pegasi (also HD 203504, HR 8173, HIP 105502 and SAO 107073) is a magnitude +4.09 spectroscopic binary star located 156 light-years away in the constellation Pegasus. 1 Pegasi is a giant orange star of spectral type K1III with an effective temperature of 4671 ± 24 K. It is 60 times more luminous than the sun, and its radius is 12 times greater than the Sun's diameter. The star has a rotational speed of only 1.2 m/s. 1 Pegasi has a metallicity abundance lower than the sun ([Fe/H] = -0.14), and an estimated age of nearly 4000 million years. It was part of the, now discarded, ancient constellation of Tigris.
The galactic kinematics indicate to that of a member of the 'Hercules moving group' (this is a large group of stars near the solar system whose speed of rotation around the galactic center differs significantly from that of the vast majority of stars in the Milky Way). 1 Pegasi forms a binary system, separated by 36 arcsec, with a magnitude +8.4 star. The companion is, in turn, a spectroscopic binary with an orbital period of 3.04 years. The main component of this binary is an orange dwarf type of K0V.
Right ascension 21h 22m 05.19928s, Declination +19° 48' 16.2364"
