| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Centaurus |
| Right ascension | 11h 43m 31.193s[2] |
| Declination | –62° 29′ 21.82″[2] |
| Apparent magnitude (V) | 5.021var[1] |
| Characteristics | |
| Spectral type | G0 0-Ia[3](F8Ia + B0III[1]) |
| U−Bcolor index | 1.762[1] |
| B−Vcolor index | 0.014[1] |
| Variable type | SRd[4] |
| Astrometry | |
| Radial velocity (Rv) | 16.44[5] km/s |
| Proper motion (μ) | RA: –5.74 ± 0.21[2]mas/yr Dec.: 1.30 ± 0.17[2]mas/yr |
| Parallax (π) | 0.1537±0.0927 masGaia DR3[6] |
| Distance | 3,300 - 3,500[1] pc |
| Absolute magnitude (MV) | -8.4/-5.1[1] |
| Details[1] | |
| Mass | 20/25 M☉ |
| Radius | 420/14 R☉ |
| Luminosity | 200,000/125,000 L☉ |
| Surface gravity (log g) | 0.7/3.5 cgs |
| Temperature | 6,010/29,000 K |
| Other designations | |
| HIP 57175,SAO 251555,CD-61° 3163,HR 4511,CPD-61° 2559,HD 101947. | |
| Database references | |
| SIMBAD | data |
V810 Centauri is adouble star consisting of ayellow hypergiant[3] primary (V810 Cen A) andblue giant secondary (V810 Cen B). It is a small amplitudevariable star, entirely due to the supergiant primary which is visually over three magnitudes (about 12x) brighter than the secondary.[7] It is the MK spectral standard for class G0 0-Ia.[3] A 5thmagnitude star, it is visible to thenaked eye under good observing conditions.
Maurice Pim FitzGerald announced that the star's brightness varies, in 1973.[8] It was given itsvariable star designation, V810 Centauri, in 1979.[9]V810 Cen A shows semi-regular variations with several component periods. The dominant mode is around 156 days and corresponds toCepheidfundamental mode radial pulsation. Without the otherstellar pulsation modes it would be considered aClassical Cepheid variable. Other pulsation modes have been detected at 89 to 234 days, with the strongest being a possible non-radial p-mode at 107 days and a possible non-radial g-mode at 185 days.[1]
The blue giant secondary has a similar mass and luminosity to the supergiant primary, but is visually much fainter. The primary is expected to have lost around 5 M☉ since it was on themain sequence, and has expanded and cooled so it lies at the blue edge of the Cepheidinstability strip. It is expected to get no cooler and may perform ablue loop while slowly increasing in luminosity.[1]
V810 Cen was once thought to be a member of theStock 14open cluster at 2.6 kpc,[10] but appears to be more distant (3.2-3.5 kpc) based on spectrophotometric study.[3] The distance derived fromGaiaparallax measurements is even larger, between 4 kpc and 16 kpc.[6]
