Eta Sculptoris

Eta Sculptoris, Latinized from η Sculptoris, is a single,[8] variable star in the central part[9] of the southern constellation of Sculptor. It is visible to the naked eye as a faint, red-hued star with an apparent visual magnitude that fluctuates around 4.81.[5] The star is located approximately 460 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +12 km/s.[6]

A light curve for Eta Sculptoris, plotted from MASCARA data folded with the best-fit period of 24.22 days[10]
Eta Sculptoris
Location of η Sculptoris (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Sculptor
Right ascension 00h 27m 55.69820s[1]
Declination −33° 00′ 25.7900″[1]
Apparent magnitude (V) 4.8 - 4.9[2]
Characteristics
Evolutionary stage asymptotic giant branch[3]
Spectral type M4III[4]
U−B color index +1.81[5]
B−V color index +1.64[5]
Variable type SRS[2]
Astrometry
Radial velocity (Rv)+12.1±1.7[6] km/s
Proper motion (μ) RA: −20.349[1] mas/yr
Dec.: −49.911[1] mas/yr
Parallax (π)7.0975 ± 0.2769 mas[1]
Distance460 ± 20 ly
(141 ± 5 pc)
Absolute magnitude (MV)−0.83[7]
Details
Radius79.96+3.70
−9.85[1] R☉
Luminosity1,012.3±44.6[1] L☉
Temperature3,641+247
−82[1] K
Other designations
η Scl, CD−33°152, FK5 2026, GC 544, HD 2429, HIP 2210, HR 105, SAO 192545, GSC 06994-01104
Database references
SIMBADdata

This object is an aging red giant star,[4] currently on the asymptotic giant branch,[3] with a stellar classification of M4III.[4] With the supply of hydrogen at its core exhausted, the star has cooled and expanded. It now has 80 times the radius of the Sun.[1] Eta Sculptoris is classified as a semiregular variable with a visual magnitude that fluctuates between +4.80 and +4.90,[2] The pulsations have periods of 22.7, 23.5, 24.6, 47.3, 128.7 and 158.7 days.[11] On average, this star is radiating over a thousand times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 3,641 K.[1]

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. Watson, Christopher (August 25, 2009). "Eta Sculptoris". AAVSO Website. American Association of Variable Star Observers. Retrieved 20 July 2014.
  3. Eggen, Olin J. (July 1992). "Asymptotic giant branch stars near the sun". Astronomical Journal. 104 (1): 275–313. Bibcode:1992AJ....104..275E. doi:10.1086/116239.
  4. Hoffleit, D.; Warren, W. H. (1995). "VizieR Online Data Catalog: Bright Star Catalogue". VizieR On-line Data Catalog: V/50. Originally Published in: 1964BS....C......0H (5th Revised ed.). 5050. Bibcode:1995yCat.5050....0H.
  5. 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.
  6. 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.
  7. 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. Vizier catalog entry
  8. Eggleton, P. P.; Tokovinin, A. A. (September 2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society. 389 (2): 869–879. arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x. S2CID 14878976.
  9. Streicher, Magda (December 2008). "The Sculptor's feast in art". Monthly Notes of the Astronomical Society of South Africa. 67 (11 and 12): 219–223. Bibcode:2008MNSSA..67..219S.
  10. "MASCARA bright variable stars light curves". Centre de Données astronomiques de Strasbourg. University of Strabourg. Retrieved 1 December 2022.
  11. Tabur, V.; Bedding, T. R. (2009). "Long-term photometry and periods for 261 nearby pulsating M giants". Monthly Notices of the Royal Astronomical Society. 400 (4): 1945–61. arXiv:0908.3228. Bibcode:2009MNRAS.400.1945T. doi:10.1111/j.1365-2966.2009.15588.x. S2CID 15358380.
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