HD 177765 is a white-hued star in the southern constellation of Sagittarius. With an apparent magnitude of 9.15, it is too faint to be seen by the naked eye from Earth, but is dimly visible using binoculars. It is located at a distance of 1284ly according to Gaia EDR3 parallax measurements.
The star is classified as a rapidly oscillating Ap star (roAp star). It shows super-solar abundances of chromium and strontium as well as many rare-earth elements such as europium and cerium, but is depleted of carbon and nickel. In 2012, the star was found to pulsate with a low radial velocity amplitude of 7 - 150 m/s and a period of 23.6 minutes, the latter being the longest out of any known roAp star at the time. Two additional pulsation frequencies were detected in 2016.
The precise stellar parameters vary from publication to publication, but the star is considered to be part of a group of evolved roAp stars with long pulsation periods, alongside β CrB A and HD 116114. The existence of this group implies a systematic shift of rare-earth emission line anomalies as roAp stars age.