Astronomy:Eta Sculptoris

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Short description: Star in the constellation Sculptoris
Eta Sculptoris
Sculptor constellation map.svg
Red circle.svg
Location of η Sculptoris (circled)
Observation data
Equinox J2000.0]] (ICRS)
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[1] mas
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
Database references
SIMBADdata

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]

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. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G.  Gaia DR2 record for this source at VizieR.
  2. ↑ 2.0 2.1 2.2 Watson, Christopher (August 25, 2009). "Eta Sculptoris". AAVSO Website. American Association of Variable Star Observers. http://www.aavso.org/vsx/index.php?view=detail.top&oid=34115. 
  3. ↑ 3.0 3.1 Eggen, Olin J. (July 1992). "Asymptotic giant branch stars near the sun". Astronomical Journal 104 (1): 275–313. doi:10.1086/116239. Bibcode: 1992AJ....104..275E. 
  4. ↑ 4.0 4.1 4.2 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 5050. Bibcode: 1995yCat.5050....0H. 
  5. ↑ 5.0 5.1 5.2 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. 
  6. ↑ 6.0 6.1 Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters 32 (11): 759–771. doi:10.1134/S1063773706110065. Bibcode: 2006AstL...32..759G. 
  7. ↑ Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A.  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. doi:10.1111/j.1365-2966.2008.13596.x. Bibcode: 2008MNRAS.389..869E. 
  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". University of Strabourg. https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/617/A32. 
  11. ↑ "Long-term photometry and periods for 261 nearby pulsating M giants". Monthly Notices of the Royal Astronomical Society 400 (4): 1945–61. 2009. doi:10.1111/j.1365-2966.2009.15588.x. Bibcode: 2009MNRAS.400.1945T. 



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