R Sculptoris
Variable star in the constellation Sculptor
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R Sculptoris is a variable star system in the southern constellation of Sculptor.[13][14] Parallax measurements provide a distance estimate of approximately 1,435 ± 98 light-years from the Sun.[2] An independent estimate based on measurements of an ejected shell surrounding the star yield a distance of 1,180 ± 140 light-years.[9] The star is drifting closer with a radial velocity of −5.4 km/s.[8]
 | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Sculptor[1] |
| Right ascension | 01h 26m 58.09462s[2] |
| Declination | −32° 32′ 35.4377″[2] |
| Apparent magnitude (V) | +5.5 - 8.0[3] |
| Characteristics | |
| Evolutionary stage | AGB[4] |
| Spectral type | C6,5ea(Np)[5] |
| U−B color index | +7.67[6] |
| B−V color index | +3.87[6] |
| Variable type | SRb[7] |
| Astrometry | |
| Radial velocity (Rv) | −5.40[8] km/s |
| Proper motion (μ) | RA: −9.784[2] mas/yr Dec.: −30.900[2] mas/yr |
| Parallax (π) | 2.2724±0.1471 mas[2] |
| Distance | 1,180±140 ly (361±44 pc)[9] |
| Absolute magnitude (MV) | −0.45[1] |
| Details | |
| Mass | 1.3±0.7 [10] M☉ |
| Radius | 411±43[11] R☉ |
| Luminosity | 8,000±1,000[11] L☉ |
| Surface gravity (log g) | −0.5±0.1[11] cgs |
| Temperature | 2640±80 [10] K |
| Metallicity [Fe/H] | 0.0[5] dex |
| Other designations | |
| R Scl, CD−33°525, HD 8879, HIP 6759, HR 423, SAO 193122, WDS J01270-3233A, AAVSO 0122-33[12] | |
| Database references | |
| SIMBAD | data |
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.[15] 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.[16][17]
This is an aging giant star on the asymptotic giant branch with a stellar classification of C6,5ea(Np),[5] which indicates a carbon-rich atmosphere. It is a semi-regular pulsating star of the SRb[7] 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.[9]
Observations have revealed a spiral structure in the material around the star.[19] The spiral is suspected to be caused by an unseen companion star.[13] The spiral windings are consistent with an orbital period of ~350 years.[19]
Gallery
This image captures approximately 20x20 milliarcseconds.[20]
Spiral spotted by ALMA around the star (data visualisation).
R Sculptoris and its hidden companion, taken by Hubble Space Telescope
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