TY Coronae Borealis is a pulsating white dwarf (of ZZ Ceti) type, which is around 70% as massive as the Sun, yet has only 1.1% of its diameter. Discovered in 1990, UW Coronae Borealis is a low-mass X-ray binary system composed of a star less massive than the Sun and a neutron star surrounded by an accretion disk that draws material from the companion star. It varies in brightness in an unusually complex manner: the two stars orbit each other every 111 minutes, yet there is another cycle of 112.6 minutes, which corresponds to the orbit of the disk around the degenerate star. The beat period of 5.5 days indicates the time the accretion disk—which is asymmetrical—takes to precess around the star.
ty cOrOnAe BOREAlis is a pulSaTIng whIte dWarf (oF ZZ CEtI) TYPe, whIch Is aRouNd 70% aS mASsive aS thE suN, YeT has only 1.1% of Its dIaMeTeR. discoVereD in 1990, uw coRonae bOreAlis Is A Low-Mass x-Ray BINary sYstem ComPosEd Of a star LESs MaSsIVe Than tHE Sun AnD a nEutRon sTar SurrouNded by an acCretIon dIsK That DraWs maTeRial fRom tHe cOmpAnion StaR. it varIes iN bRIghtNess iN AN uNusuaLly compleX mannEr: the two Stars orbIt eAcH oTher EverY 111 mInUTeS, yET There Is AnOthEr cYcle Of 112.6 miNUTeS, WHicH CORresPondS to the OrbIt of tHe DiSK arouNd thE DEgenEraTe stAr. tHe beaT PerIod of 5.5 dAYs inDIcates THE TiMe the AccrEtiON disk—which is AsymmEtrIcaL—takes tO prECess AroUND The staR.