GR Andromedae (often abbreviated to GR And) is a variable star in the constellation Andromeda. Its apparent visual magnitude varies between 6.87 and 6.95 in a cycle of 518.2 days.[1] It is classified as an α2 Canum Venaticorum variable.[3]
The radiation emitted by GP Andromedae is a typical stellar blackbody with absorption lines from various elements, which gives to the star a spectral type A2pSrCrEu, meaning that unusually strong lines of strontium, chromium and europium can be observed.[3] GP Andromedae is thus classified as an Ap star. The intensity and profile of the spectral lines varies within a cycle with the same period as the brightness variations.[8]
Photometric and spectral variability of GR Andromedae is typical of a star with a strong and variable magnetic field. This way, the 518.2 days periodicity can be identified as the rotation period of the star.[8] It's among the slowest rotators in the category of magnetic chemically peculiar stars, with a calculated equatorial rotation rate of only 0.2 km/s.[1]