M3-type semiregular variable star in the constellation Corona Borealis
 ;/td ;
! style="text-align: center; background-color: #FFFFC0;" colspan="2" | Observation dataEpoch J2000      Equinox J2000
! style="text-align:left" | Constellation
! style="text-align:left" | Right ascension
! style="text-align:left" | Declination
! style="text-align:left" | Apparent magnitude (V)
! style="background-color: #FFFFC0; text-align: center;" colspan="2"| Characteristics
! style="text-align:left" | Spectral type
! style="text-align:left" | Variable type
 ;/th ; ;/tr ;
 ;/th ; ;/tr ;
RR Coronae Borealis (RR CrB, HD 140297, HIP 76844) is a M3-type semiregular variable star located in the constellation Corona Borealis with a parallax of 2.93mas being a distance of . It varies between magnitudes 7.3 and 8.2 over 60.8 days. Located around 1228 light-years distant, it shines with a luminosity approximately 2180 times that of the Sun and has a surface temperature of 3309 K.
In 1907 it was announced that Williamina Fleming had discovered that the star, listed then as BD +39° 2901, is a variable star. She had determined that from the examination of 26 photographic plates taken from 1892 to 1907. It was given its variable star designation, RR Coronae Borealis, in 1908.
References.
 ;templatestyles src="Reflist/styles.css" / ;