R Sculptoris

R Sculptoris is a variable star system in the southern constellation of Sculptor.[9][10] 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.[11] The star is drifting closer with a radial velocity of −5.4 km/s.[5]

R Sculptoris
Location of R Sculptoris (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Sculptor
Right ascension 01h 26m 58.09462s[1]
Declination −32° 32′ 35.4377″[1]
Apparent magnitude (V) +5.72[2]
Characteristics
Spectral type C6,5ea(Np)[3]
U−B color index +7.67[2]
B−V color index +3.87[2]
Variable type SRb[4]
Astrometry
Radial velocity (Rv)−5.40[5] km/s
Proper motion (μ) RA: −9.784[1] mas/yr
Dec.: −30.900[1] mas/yr
Parallax (π)2.2724 ± 0.1471[1] mas
Distance1,440 ± 90 ly
(440 ± 30 pc)
Absolute magnitude (MV)−0.45[6]
Details[7]
Mass1.3±0.7 M☉
Radius138.61+1.24
−0.16[1] R☉
Luminosity2,068±171[1] L☉
Surface gravity (log g)−0.6±0.4 cgs
Temperature3,306+2
−15[1] K
Metallicity [Fe/H]0.0[3] dex
Other designations
R Scl, CD−33°525, HD 8879, HIP 6759, HR 423, SAO 193122, WDS J01270-3233A, AAVSO 0122-33[8]
Database references
SIMBADdata

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.[11]

Observations have revealed a spiral structure in the material around the star.[12] The spiral is suspected to be caused by an unseen companion star.[9] The spiral windings are consistent with an orbital period of ~350 years.[12]

  • Spiral spotted by ALMA around the star (data visualisation).
  • R Sculptoris and its hidden companion, taken by Hubble Space Telescope

References
  1. 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.
  2. 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.
  3. 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.
  4. 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.
  5. 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.
  6. 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
  7. 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.
  8. "R Scl". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-12-06.
  9. "Hubble Gazes at R Sculptoris and its Hidden Companion". SpaceDaily. 11 January 2015.
  10. "Curious spiral spotted by ALMA around red giant star R Sculptoris (data visualisation)". Image Archive. ESO. Retrieved 11 October 2012.
  11. 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. A102.
  12. 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.
  13. "A red giant sheds its skin". www.eso.org. Retrieved 12 February 2018.

Further reading
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