Beta Circini
Star in the constellation Circinus
From Wikipedia, the free encyclopedia
Beta Circini is the second-brightest star in the constellation of Circinus. Its name is a Bayer designation that is Latinized from β Circini, and abbreviated Beta Cir or β Cir. The star has an apparent visual magnitude of approximately 4.07,[1] which is bright enough to be viewed with the naked eye. Based upon an annual parallax shift of 35.8 mas as seen from the Earth, it is located at a distance of 91.1 light-years (27.9 pc) from the Sun.
 | |
| Observation data Epoch J2000.0 Equinox ICRS | |
|---|---|
| Constellation | Circinus[1] |
| Right ascension | 15h 17m 30.84945s[2] |
| Declination | −58° 48′ 04.3453″[2] |
| Apparent magnitude (V) | 4.07[1] |
| Characteristics | |
| Spectral type | A3 Va[3] |
| U−B color index | +0.09[4] |
| B−V color index | +0.088±0.007[1] |
| Astrometry | |
| Radial velocity (Rv) | 9.6±2[5] km/s |
| Proper motion (μ) | RA: −97.182 mas/yr[2] Dec.: −136.055 mas/yr[2] |
| Parallax (π) | 35.8205±0.2515 mas[2] |
| Distance | 91.1 ± 0.6 ly (27.9 ± 0.2 pc) |
| Absolute magnitude (MV) | +1.64[1] |
| Details | |
| Mass | 1.96+0.03 −0.01[6] M☉ |
| Radius | 1.92[7] R☉ |
| Luminosity | 19[1] L☉ |
| Surface gravity (log g) | 4.281[8] cgs |
| Temperature | 8676±33[6] K |
| Metallicity [Fe/H] | 0.16[1] dex |
| Rotational velocity (v sin i) | 59[4] km/s |
| Age | 370–500[6] Myr |
| Other designations | |
| β Cir, Beta Circini, Beta Cir, CPD−58 5875, FK5 561, GC 20526, GJ 580.1,, GJ 9516, HD 135379, HIP 74824, HR 5670, SAO 242384, PPM 343590[9] | |
| Database references | |
| SIMBAD | data |
With a stellar classification of A3 Va,[3] this is an A-type main-sequence star fusing atoms of hydrogen into helium at its core. It is between 370 and 500 million years old[6] and is spinning with a projected rotational velocity of 59 km/s.[4] The star has 1.96[6] times the mass of the Sun and around 1.9[7] times the Sun's radius. The star is radiating 19[1] times the Sun's luminosity from its photosphere at an effective temperature of 8,676 K.[6] It has one known sub-stellar companion.
Substellar companion
Beta Circini b is a distant brown dwarf companion orbiting the host star at a distance of 6,656 AU. It was detected as a proper motion companion to Beta Circini in 2015 by L.C. Smith and collaborators. Using BHAC15 isochrones, its mass is estimated at 0.056 M☉, or 59 MJ. It has a stellar classification of L1 and a temperature of 2,084 K (1,811 °C).[6]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination (°) |
Radius |
|---|---|---|---|---|---|---|
| b | 58.7±7.3 MJ | 6,656 | — | — | — | — |