R Sculptoris
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Sculptor |
| Right ascension | 01h 26m 58.09462s |
| Declination | −32° 32′ 35.4377″ |
| Apparent magnitude (V) | +5.72 |
| Characteristics | |
| Spectral type | C6,5ea(Np) |
| U−B color index | +7.67 |
| B−V color index | +3.87 |
| Variable type | SRb |
| Astrometry | |
| Radial velocity (Rv) | −5.40 km/s |
| Proper motion (μ) | RA: −9.784 mas/yr Dec.: −30.900 mas/yr |
| Parallax (π) | 2.2724±0.1471 mas |
| Distance | 1,180±140 ly (361±44 pc) |
| Absolute magnitude (MV) | −0.45 |
| Details | |
| Mass | 1.3±0.7 M☉ |
| Radius | 411±43 R☉ |
| Luminosity | 8,000±1,000 L☉ |
| Surface gravity (log g) | −0.5±0.1 cgs |
| Temperature | 2640±80 K |
| Metallicity [Fe/H] | 0.0 dex |
| Other designations | |
| R Scl, CD−33°525, HD 8879, HIP 6759, HR 423, SAO 193122, WDS J01270-3233A, AAVSO 0122-33 | |
| Database references | |
| SIMBAD | data |
R Sculptoris is a variable star system in the southern constellation of Sculptor. Parallax measurements provide a distance estimate of approximately 1,435 ± 98 light-years from the Sun. An independent estimate based on measurements of an ejected shell surrounding the star yield a distance of 1,180 ± 140 light-years. The star is drifting closer with a radial velocity of −5.4 km/s.
Benjamin Apthorp Gould discovered that the star's brightness varies, in 1872. It was listed with its variable star designation, R Sculptoris, in Annie Jump Cannon's 1907 work Second Catalog of Variable Stars. Although the General Catalogue of Variable Stars lists its maximum brightness as magnitude 9.1, far too faint to be seen with the naked eye, both AAVSO and ASAS data shows that R Sculptoris is occasionally brighter than 6th magnitude, and faintly visible to the naked eye under excellent observing conditions.
This is an aging giant star on the asymptotic giant branch with a stellar classification of C6,5ea(Np), which indicates a carbon-rich atmosphere. It is a semi-regular pulsating star of the SRb type that is nearing the end of its fusing lifespan. A sine curve fitted to the last ten pulsation cycles prior to 2017 give a pulsation period of 376 days with an amplitude of 0.75 magnitude. The star is shedding its outer atmosphere, and it is surrounded by a thin shell of dust and gas that was created during the most recent thermal pulse around 2,000 years ago.
Observations have revealed a spiral structure in the material around the star. The spiral is suspected to be caused by an unseen companion star. The spiral windings are consistent with an orbital period of ~350 years.