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R Sculptoris
	Location of R Sculptoris (circled)
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	1177±143 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.^[11]^[12] Parallax measurements provide a distance estimate of approximately 1,435 ± 98 light-years from the Sun.^[1] An independent estimate based on measurements of an ejected shell surrounding the star yield a distance of 1,180 ± 140 light-years.^[6] The star is drifting closer with a radial velocity of −5.4 km/s.^[5]

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.^[13] Although the General Catalogue of Variable Stars lists its maximum brightness as magnitude 9.1,^[14] 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.^[15]^[16]

A visual band light curve for R Sculptoris, plotted from *ASAS* data^[17]

This is an aging giant star on the asymptotic giant branch with a stellar classification of C6,5ea(Np),^[3] which indicates a carbon-rich atmosphere. It is a semi-regular pulsating star of the SRb^[4] 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.^[6]

Observations have revealed a spiral structure in the material around the star.^[18] The spiral is suspected to be caused by an unseen companion star.^[11] The spiral windings are consistent with an orbital period of ~350 years.^[18]

Gallery

This image captures approximately 20x20 milliarcseconds.^[19]
Spiral spotted by ALMA around the star (data visualisation).
R Sculptoris and its hidden companion, taken by Hubble Space Telescope

References

^ ^a ^b ^c ^d ^e ^f Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
^ ^a ^b ^c Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237. Bibcode:2002yCat.2237....0D.
^ ^a ^b ^c Cruzalèbes, P.; et al. (2013). "Fundamental parameters of 16 late-type stars derived from their angular diameter measured with VLTI/AMBER". Monthly Notices of the Royal Astronomical Society. 434 (1): 437. arXiv:1306.3288. Bibcode:2013MNRAS.434..437C. doi:10.1093/mnras/stt1037. S2CID 49573767.
^ ^a ^b Samus, N. N.; et al. (2009). "General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
^ ^a ^b Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. S2CID 119231169.
^ ^a ^b ^c Maercker, M.; et al. (April 2018). "An independent distance estimate to the AGB star R Sculptoris". Astronomy & Astrophysics. 611: 8. arXiv:1711.09676. Bibcode:2018A&A...611A.102M. doi:10.1051/0004-6361/201732057. S2CID 56318815. A102.
^ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644
^ ^a ^b Wittkowski, M; et al. (2017). "Aperture synthesis imaging of the carbon AGB star R Sculptoris. Detection of a complex structure and a dominating spot on the stellar disk". Astronomy & Astrophysics. 601: A3. arXiv:1702.02574. Bibcode:2017A&A...601A...3W. doi:10.1051/0004-6361/201630214. S2CID 56160169.
^ ^a ^b ^c Drevon, J.; Millour, F.; Cruzalèbes, P.; Paladini, C.; Hron, J.; Meilland, A.; Allouche, F.; Hofmann, K.-H.; Lagarde, S.; Lopez, B.; Matter, A.; Petrov, R.; Robbe-Dubois, S.; Schertl, D.; Scicluna, P. (2022-09-01). "Locating dust and molecules in the inner circumstellar environment of R Sculptoris with MATISSE". Astronomy & Astrophysics. 665: A32. arXiv:2208.10845. Bibcode:2022A&A...665A..32D. doi:10.1051/0004-6361/202141609. ISSN 0004-6361.
^ "R Scl". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-12-06.
^ ^a ^b "Hubble Gazes at R Sculptoris and its Hidden Companion". SpaceDaily. 11 January 2015.
^ "Curious spiral spotted by ALMA around red giant star R Sculptoris (data visualisation)". Image Archive. ESO. Retrieved 11 October 2012.
^ Cannon, Annie J. (1907). "Second catalogue of variable stars". Annals of Harvard College Observatory. 55: 1–94. Bibcode:1907AnHar..55....1C. Retrieved 16 December 2024.
^ Samus, N.N.; Kazarovets, E.V.; Durlevich, O.V.; Kireeva, N.N.; Pastukhova, E.N. "R Scl". General Catalogue of Variable Stars. Lomonosov Moscow State University. Retrieved 16 December 2024.
^ "Plot a light curve". American Association of Variable Star Observers. Retrieved 16 December 2024.
^ "ASAS All Star Catalogue". University of Warsaw. Retrieved 16 December 2024.
^ "ASAS All Star Catalogue". The All Sky Automated Survey. Retrieved 8 December 2021.
^ ^a ^b Maercker, M.; et al. (2012). "Unexpectedly large mass loss during the thermal pulse cycle of the red giant star R Sculptoris". Nature. 490 (7419): 232–4. arXiv:1210.3030. Bibcode:2012Natur.490..232M. doi:10.1038/nature11511. PMID 23060194. S2CID 4417744.
^ "A red giant sheds its skin". www.eso.org. Retrieved 12 February 2018.