RT Sculptoris

RT Sculptoris
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Sculptor
Right ascension 00h 36m 28.090s[1]
Declination −25° 40′ 22.93″[1]
Apparent magnitude (V) 10.18
Min I: 10.89
Min II: 10.47[2]
Characteristics
Spectral type A5n + F3[2]
Variable type Semidetached β Lyr?[2]
Astrometry
Radial velocity (Rv)+30.6[3] km/s
Proper motion (μ) RA: 29.248 mas/yr[1]
Dec.: 34.121 mas/yr[1]
Parallax (π)3.4604±0.0198 mas[1]
Distance943 ± 5 ly
(289 ± 2 pc)
Orbit[4]
Period (P)0.51156012 d[2]
Semi-major axis (a)≥ 3.52±0.14 R☉
Semi-amplitude (K1)
(primary)		105.2±1.8 km/s
Details[5]
Primary
Mass1.37 ± 0.01 M☉
Radius1.53 ± 0.01 R☉
Metallicity [Fe/H]−0.75[6] dex
Secondary
Mass0.61 ± 0.01 M☉
Radius0.97 ± 0.01 R☉
Other designations
RT Scl, CD−26°179, HIP 118149, SAO 108933, PPM 143009, WDS J23579+1557A[7]
Database references
SIMBADdata

RT Sculptoris is an eclipsing binary star system in the southern constellation of Sculptor. With a typical apparent visual magnitude of 10.18, it is much too faint to be visible with the naked eye. Based on parallax measurements, it is located at a distance of approximately 943 light-years (289 pc) from the Earth. The system is receding from the Sun with a line of sight velocity component of +30.6 km/s.[3]

Observations

In 1908, this system was discovered to be an eclipsing variable of the Beta Lyrae type by Ida Whiteside,[8] a volunteer observer at Harvard College Observatory.[9] It showed continuous variability with two maxima and two minima, having a period of 0.511574 days.[8] By 1925, the period had been refined to 0.51156935±0.00000009 days, with the interval between the primary and secondary minima being only 45% of the period from one primary minimum to the next.[10]

By 1958, it became evident that the orbital period of RT Sculptoris was not constant. The period measured in October 1954 had decreased to 0.51156249 days, or one second shorter over a period of 50 years. The light curve for the system showed the two maxima are slightly unequal and are not flat topped.[11] The pair undergo partial eclipses with the primary minimum being caused by an occultation. The secondary minimum was found to be displaced and asymmetrical, showing a steeper descent on the descending branch compared to the ascending branch.[12]

This system was found metal-deficient compared to the Sun.[6] It was proposed that the confirmed period change could be explained by a mass exchange between the two components. In this model, the higher mass component is filling its Roche lobe, forming a semi-detached binary.[13] The overflow is being accreted by the secondary, creating a small hot spot. The mass transfer rate is estimated at 1.3×10−8 M☉ per year. The primary appears to be a late A-type star, while there is some disagreement about the secondary; the latter has been modelled as an F-, G- and even K-type star.[5]

References

  1. ^ a b c d Vallenari, A.; et al. (Gaia collaboration) (2023), "Gaia Data Release 3. Summary of the content and survey properties", Astronomy and Astrophysics, 674: A1, arXiv:2208.00211, Bibcode:2023A&A...674A...1G, doi:10.1051/0004-6361/202243940, S2CID 244398875. Gaia DR3 record for this source at VizieR.
  2. ^ a b c d Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, GCVS 5.1, 61 (1): 80–88, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 255195566.
  3. ^ a b Duflot, M.; et al. (1995), "Vitesses radiales. Catalogue WEB: Wilson Evans Batten. Subtitle: Radial velocities: The Wilson-Evans-Batten catalogue", Astronomy and Astrophysics Supplement Series, 114: 269, Bibcode:1995A&AS..114..269D.
  4. ^ Hilditch, R. W.; King, D. J. (December 1986), "Contact and near-contact binary systems - IV. RT Scl and AQ Tuc", Monthly Notices of the Royal Astronomical Society, 223: 581–593, Bibcode:1986MNRAS.223..581H, doi:10.1093/mnras/223.3.581.
  5. ^ a b Banks, Timothy; et al. (November 1990), "RT-Sculptoris - an Important Star for Low Mass Close Binary Research", Astrophysics and Space Science, 173 (1): 77–92, Bibcode:1990Ap&SS.173...77B, doi:10.1007/BF00642564.
  6. ^ a b Clausen, J. V.; Grønbech, B. (June 1977), "Four-colour light curves of the eclipsing binary RT Scl.", Astronomy and Astrophysics, Supplement Series, 28: 389–401, Bibcode:1977A&AS...28..389C.
  7. ^ "RT Scl", SIMBAD, Centre de données astronomiques de Strasbourg, retrieved 2026-04-20.
  8. ^ a b Whiteside, Ida; Pickering, Edward C. (July 1908), "-26° 179. A New Variable of the Class of β Lyrae. 003226", Harvard College Observatory Circular, 139: 1–7, Bibcode:1908HarCi.139....1W.
  9. ^ Zrull, Lindsay Smith (May 2021), "Women in Glass: Women at the Harvard Observatory during the Era of Astronomical Glass Plate Photography, 1875-1975", Journal for the History of Astronomy, 52 (2): 115–146, Bibcode:2021JHA....52..115Z, doi:10.1177/00218286211000470, retrieved 2026-04-20.
  10. ^ Schilt, J. (November 1925), "On the light-curve of RT Sculptoris", Bulletin of the Astronomical Institutes of the Netherlands, 3: 63, Bibcode:1925BAN.....3...63S.
  11. ^ Cillié, G. G.; Lindsay, E. M. (1958), "The photo-electric light curve of RT Sculptoris", Monthly Notices of the Royal Astronomical Society, 118: 585, Bibcode:1958MNRAS.118..585C, doi:10.1093/mnras/118.6.585.
  12. ^ Bookmyer, Beverly B. (December 1966), "Orbital solutions of V499 Scorpii and RT Sculptoris", Astronomical Journal, 71: 1012–1016, Bibcode:1966AJ.....71.1012B, doi:10.1086/110189.
  13. ^ Rafert, J. B.; Wilson, R. E. (March 1984), "An Attempt to Understand RT-Sculptoris", Astrophysics and Space Science, 100 (1–2): 117–127, Bibcode:1984Ap&SS.100..117R, doi:10.1007/BF00651590.

Further reading

  • Sushma, D.; et al. (2008), "Photometric and Spectroscopic study of RT Sculptoris", Procedings of the 25th meeting of ASI (2007), p. 64, Bibcode:2008BASIP..25...64S.
  • Duerbeck, H. W.; Karimie, M. T. (June 1979), "On the Decreasing Period and Asymmetric Light Curve of RT Sculptoris", Information Bulletin on Variable Stars, 1617: 1, Bibcode:1979IBVS.1617....1D.
  • Dugan, Raymond Smith (1928), "The Eclipsing Variables X Trianguli, RT Sculptoris", Contributions from the Princeton University Observatory, 8: 1–19, Bibcode:1928CoPri...8....1D.
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