RR Centauri is a variable star of apparent magnitude maximum +7.29. It is located in the constellation of Centaurus, approximately 320 light years distant from the solar system.[6]

RR Centauri

Light curve of RR Cen.
Observation data Epoch J2000      Equinox J2000
Constellation	Centaurus
Right ascension	14h 16m 57.22s[1]
Declination	−57° 51′ 15.6″[1]
Apparent magnitude (V)	7.29[2] (7.27 - 7.68[3])
Characteristics
Spectral type	F0 V[4]
U−B color index	+0.05[2]
B−V color index	+0.36[2]
Variable type	W Uma[3]
Astrometry
Radial velocity (Rv)	-16.0 [5] km/s
Proper motion (μ)	RA: -52.00[6] mas/yr Dec.: -22.63[6] mas/yr
Parallax (π)	10.16 ± 0.61 mas[6]
Distance	320 ± 20 ly (98 ± 6 pc)
Absolute magnitude (MV)	+1.882[4]
Orbit[7]
Primary	RR Cen1
Companion	RR Cen2
Period (P)	0.60569 days
Semi-major axis (a)	3.92 ± 0.19 R☉
Eccentricity (e)	0
Inclination (i)	81.00 ± 0.44°
Details[7]
RR Cen1
Mass	1.82 ± 0.26 M☉
Radius	2.1 ± 0.01 R☉
Luminosity	8.89 L☉
Temperature	6,912 K
RR Cen2
Mass	0.38 ± 0.06 M☉
Radius	1.05 ± 0.03 R☉
Luminosity	2.2 L☉
Temperature	6,891 ± 13 K
Other designations
RR Cen, 2MASS J14165721-5751156, HD 124689, HIP 69779, SAO 241587, TYC 8686-210-1, Cordoba Durchmusterung CD-57 5498[1]
Database references
SIMBAD	data

The system is a contact binary of the W UMa type - two stars in physical contact whose two components share a gaseous envelope. Its spectral type is A9V or F0V.[1] The binary nature of the star was discovered in 1896 by the Scottish-South African astronomer Alexander Roberts, so the system has been well observed for over a century.[8] The primary component has a mass of 1.82 solar masses, an effective temperature of around 6900 K, and a radius somewhat larger than twice the solar radius.[7] The secondary component is 0.39 solar masses, giving a mass ratio of the system (q) of 0.210. the secondary has a temperature of about 6890 K and a radius is almost equal to the solar radius.

The orbital period of this system is 0.6057 days (14.53 hours). Recent calculations by astronomers from the Chinese Academy of Sciences show a possible cyclic variation in orbital period over 65.1 ± 0.4 years whose amplitude is 0.0124 ± 0.0007 days.[7] The origin of this periodic variation could be due to the gravitational influence of a third object yet observed. Superimposed on this variation seems to be a secular increase in the period of 1.21 x 10 –7 days per year, suggesting that there is transfer of stellar mass from secondary to primary component. If this increase is confirmed, RR Centauri may evolve into a single rapidly rotating star.

RR Centauri is also an eclipsing binary, whose apparent brightness varies by around 0.41 magnitudes.[7]

References