Epoch J2000 Equinox J2000
|Right ascension||18h 47m 28.95s|
|Declination||−05° 42′ 18.5″|
|Apparent magnitude (V)||4.2—8.6 (naked eye)|
|Variable type||RV Tau|
|Radial velocity (Rv)||44.0 km/s|
|Parallax (π)||2.32 ± 0.82 mas|
|Distance||approx. 1,400 ly
(approx. 400 pc)
|Absolute magnitude (MV)||-2.6 (@431pc)
9400 ± 7100 L☉
HD 173819, HIP 92202, 2MASS J18472894-0542185, SAO 142620
It was discovered in 1795 by Edward Pigott at a time when only a few variable stars were known to exist. R Sct is the brightest of the RV Tau-type stars and the American Association of Variable Star Observers (AAVSO) contains over 110,000 observations of this star. At its brightest it is visible to the naked eye, and at its dimmest can be located with good binoculars. In the sky it is about 1 degree northwest of the Wild Duck Cluster (Messier 11).
Hipparcos gives a parallax of 2.32 milli-arcseconds for R Sct, giving it an estimated distance of 431 parsecs (1,410 light-years). But a period–luminosity relation similar to what is used for Cepheid variables suggests that R Sct is at a distance of 750 parsecs (2,400 light-years) with a luminosity of around 9400 Suns. But this would make R Sct twice as luminous as the next most luminous RV Tau-type star in the study. The author of the period–luminosity study doubts the high luminosity and resulting distance, and it has been argued (Matsuura2002) that R Sct is a thermal-pulsing AGB star, observed in a helium-burning phase instead of a post-AGB star. In either case the luminosity is far below the Ia-Ib spectral type would indicate (30,000-100,000 L☉ would be more typical), and R Scuti is clearly in an unusual evolutionary state.
- "R Scuti". SIMBAD Astronomical Database. Retrieved 2010-11-24.
- "GCVS Query=R Sct". General Catalogue of Variable Stars @ Sternberg Astronomical Institute, Moscow, Russia. Retrieved 2010-11-24.
- "R Sct". AAVSO: Variable Star Plotter (VSP). Retrieved 2010-11-24.
- "Spectral analysis for the RV Tau star R Sct". NOAO Education & Public Outreach. Retrieved 2010-11-24.
- absmag "M" = vmag "5.5" + absmag of G2V main sequence star "5" - 5 log (distance)
- Ruyter, S; Winckel; Dominik; Waters; Dejonghe (2005). "Strong dust processing in circumstellar discs around 6 RV Tauri stars. Are dusty RV Tauri stars all binaries?". Astronomy and Astrophysics 435 (1): 161–166. arXiv:astro-ph/0503290v1. Bibcode:2005A&A...435..161D. doi:10.1051/0004-6361:20041989.
- "R Scuti : A Favorite Among Its Class". AAVSO. Retrieved 2010-11-24.
- "GCVS Type=RV". General Catalogue of Variable Stars @ Sternberg Astronomical Institute, Moscow, Russia. Retrieved 2010-11-24.
- R Scuti on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images
- AAVSO: Quick Look View of AAVSO Observations (get recent magnitude estimates for R Sct)
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