Beta Coronae Australis

Beta Coronae Australis (Beta CrA), Latinized from β Coronae Australis, is a solitary star^[15] located in the southern constellation Corona Australis. It is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 4.10.^[2] The star is located around 470 light years distant from the Sun based on parallax,^[1] and is drifting further away with a radial velocity of 2.7 km/s.^[5] At its current distance, Beta CrA's brightness is diminished by 0.29 magnitudes due to interstellar dust.^[16]

Beta Coronae Australis

Location of β CrA (circled)
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Corona Australis
Right ascension	19h 10m 01.75580s[1]
Declination	−39° 20′ 26.8644″[1]
Apparent magnitude (V)	4.10±0.01[2]
Characteristics
Spectral type	K0 II/III CN1.5[3]
U−B color index	+1.07[4]
B−V color index	+1.20[4]
R−I color index	+0.61[4]
Astrometry
Radial velocity (Rv)	2.7±0.7[5] km/s
Proper motion (μ)	RA: +4.37 mas/yr[1] Dec.: −36.65 mas/yr[1]
Parallax (π)	6.88±0.25 mas[1]
Distance	470 ± 20 ly (145 ± 5 pc)
Absolute magnitude (MV)	−1.71[6]
Details
Mass	5.17±0.26[7] M☉
Radius	38.5±1.9[8] R☉
Luminosity	614±33[9] L☉
Surface gravity (log g)	1.26[10] cgs
Temperature	4,575±55[11] K
Metallicity [Fe/H]	+0.24[10] dex
Rotational velocity (v sin i)	6.2±2[12] km/s
Other designations
β CrA, 46 G. Coronae Australis[13], CD−39°13146, CPD−39°8327, GC 26380, HD 178345, HIP 94160, HR 7259, SAO 211005, PPM 298639[14]
Database references
SIMBAD	data

Beta CrA has a stellar classification of K0 II/III CN1.5,^[3] indicating that it is an evolved K-type star with the blended luminosity class of a bright giant and a regular giant star. The suffix CN1.5 indicates that the object has an anomalous overabundance of cyano radicals in its spectrum, making it a CN star. Having exhausted the supply of hydrogen at its core, the star has expanded to 39 times the Sun's girth.^[9] It has 5.17 times the mass of the Sun shines with a luminosity 614 times that of the Sun^[9] from its photosphere at a surface temperature of 4,575 K.^[11] Beta CrA is metal enriched (174% solar iron abundance^[10]) and spins modestly with a projected rotational velocity of 6.2 km/s.^[12]