S Arae (S Ara) is an RR Lyrae-type pulsating variable star in the constellation of Ara.[2] It has an apparent visual magnitude which varies between 9.92 and 11.24 during its 10.85-hour pulsation period,[1][3] and it exhibits the Blazhko effect.[6]
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Ara |
| Right ascension | 17h 59m 10.7311s[2] |
| Declination | −49° 26′ 00.453″[2] |
| Apparent magnitude (V) | 9.92 to 11.24[3] |
| Characteristics | |
| Spectral type | A3 II[4] |
| B−V color index | 0.9[2] |
| Variable type | RRab[3] |
| Astrometry | |
| Radial velocity (Rv) | 185 ± 655.35[2] km/s |
| Proper motion (μ) | RA: −26.24[2] mas/yr Dec.: −8.44[2] mas/yr |
| Parallax (π) | 1.1191 ± 0.0431 mas[5] |
| Distance | 2,900 ± 100 ly (890 ± 30 pc) |
| Absolute magnitude (MV) | +0.78 – +0.93[6] |
| Details | |
| Mass | 0.51 – 0.62[6] M☉ |
| Radius | 3.01[5] R☉ |
| Luminosity | 27[5] L☉ |
| Surface gravity (log g) | +2.9[6] cgs |
| Temperature | 6,563[5] K |
| Metallicity [Fe/H] | −0.90[6] dex |
| Other designations | |
| Database references | |
| SIMBAD | data |
In 1896 David Gill and Jacobus Kapteyn announced that the variability of the as yet unnamed star was "all but proved" by the Cape Carte du Ciel photographic plates.[7] In 1900, Robert T. A. Innes confirmed that the star, by then named CPD-49 10361, is a variable.[8] It was listed with its modern variable star designation, S Arae, in Annie Jump Cannon's 1907 Second Catalogue of Variable Stars.[9]
It was originally thought that S Arae was a binary whose brightness changes were caused by eclipses.[10] In 1918, Harlow Shapley included it within the Cepheid variable star class.[11] By 1939 it had been classified as an RR Lyrae variable.[12]
S Arae's large negative declination makes it a circumpolar star in Antarctica. Such a star can be monitored continuously for much of the southern hemisphere's winter, allowing a long period of observation without gaps due to daylight. It was the first star to be monitored that way at Dome C.[1] RRab type stars, like S Arae, are fundamental mode pulsating stars that have asymmetric light curves which rise to maximum brightness rapidly then fade more slowly.[13][14] The Blazhko effect modulation period for this star is 47.264 days (about 105 times longer than the main pulsation period), and three other periodicities have been detected in the light curve.[6]
References
edit- ^ a b c Chadid, M.; Vernin, J.; Mekarnia, D.; Chapellier, E.; Trinquet, H.; Bono, G. (June–July 2010). "First Antarctica light curve PAIX monitoring of the Blazhko RR Lyrae star: S Arae". Astronomy & Astrophysics. 516. Bibcode:2010A&A...516L..15C. doi:10.1051/0004-6361/201014857. Retrieved 24 October 2021.
- ^ a b c d e f g h "V* S Ara". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 10 November 2009.
- ^ a b c S Ara, database entry, The combined table of GCVS Vols I-III and NL 67–78 with improved coordinates, General Catalogue of Variable Stars Archived 20 June 2017 at the Wayback Machine, Sternberg Astronomical Institute, Moscow, Russia. Accessed on line 10 November 2009.
- ^ Stock, J.; Wroblewski, H. (1972). "A southern objective prism survey". Publ. Obs. Astron. Nacional. 2: 59. Bibcode:1972PDAUC...2...59S.
- ^ a b c d 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.
- ^ a b c d e f Zalian, C.; Chadid, M.; Vernin, J.; Abe, L.; Agabi, A. (2016). "Antarctica photometry of the Blazhko RR Lyrae star S Arae". Monthly Notices of the Royal Astronomical Society. 456 (1): 192. Bibcode:2016MNRAS.456..192Z. doi:10.1093/mnras/stv2611.
- ^ Gill, David; Kapteyn, J. C. (1896). Annals of the Cape Observatory, Vol. 3. London. p. 94. Bibcode:1896AnCap...3....1G. Retrieved 24 November 2024.
{{cite book}}: CS1 maint: location missing publisher (link) - ^ Innes, R. T. A. (November 1900). "Southern variables". Astronomical Journal. 21 (487): 55–56. doi:10.1086/103248. Retrieved 24 November 2024.
- ^ Cannon, Annie J. (1907). "Second catalogue of variable stars". Annals of Harvard College Observatory. 55: 1–94. Bibcode:1907AnHar..55....1C. Retrieved 21 November 2024.
- ^ Roberts, A. W. (April 1911). "On the variation of S Arae". Astrophysical Journal. 33: 197–216. Bibcode:1911ApJ....33..197R. doi:10.1086/141851. Retrieved 24 November 2024.
- ^ Shapley, H. (December 1918). "Studies based on the colors and magnitudes in stellar clusters. VIII. The luminosities and distances of 139 Cepheid variables". Astrophysical Journal. 48: 279–294. Bibcode:1918ApJ....48..279S. doi:10.1086/142435. Retrieved 24 November 2024.
- ^ Wilson, Ralph E. (March 1939). "The Zero Point of the Period-Luminosity Curve". Astrophysical Journal. 89. Bibcode:1939ApJ....89..218W. doi:10.1086/144038. Retrieved 24 November 2024.
- ^ Benkő, József M.; Kovács, Gábor B. (December 2023). "Similar additional frequency patterns on fundamental- and overtone-mode RR Lyrae stars showing f68 frequencies" (PDF). Astronomy & Astrophysics. 680: L6. Bibcode:2023A&A...680L...6B. doi:10.1051/0004-6361/202348062. Retrieved 24 November 2024.
- ^ "Variable Stars and Light Curves" (PDF). AAVSO. Retrieved 24 November 2024.