AH Scorpii

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AH Scorpii
Observation data
Epoch J2000       Equinox J2000
Constellation Scorpius
Right ascension 17h 11m 17.01945s [1]
Declination −32° 19′ 30.7140″ [1]
Apparent magnitude  (V)6.5 - 9.6 [2]
Characteristics
Evolutionary stage OH/IR [3] RSG
Spectral type M4-5 Ia-Iab [4]
B−V color index +2.57 [5]
Variable type SRc [4]
Astrometry
Radial velocity (Rv)−13.40±2.4 [6] km/s
Proper motion (μ)RA: −2.322±0.115 [1] mas/yr
Dec.: −2.610±0.068 [1] mas/yr
Parallax (π)0.5632±0.0799  mas [1]
Distance 7,400±620  ly
(2,260±190 [7]   pc)
Absolute magnitude  (MV)−5.8 [8]
Details
Mass 20 [9]   M☉
Radius 1,411±124 [5]   R☉
Luminosity 329,000±86,000 [5]   L☉
Surface gravity (log g)−0.5 [5]   cgs
Temperature 3,682 [5]   K
Other designations
AH  Sco, AN  223.1907, IRC −30282, RAFGL  1927, AAVSO 1704-32, CD32°12429, HD 155161, HIP 84071, GSC 07365-00527, IRAS 17080-3215, 2MASS J17111702-3219308
Database references
SIMBAD data

AH Scorpii (abbreviated to AH Sco) is a red supergiant variable star located in the constellation Scorpius. It is one of the largest stars known by radius and is also one of the most luminous red supergiant stars in the Milky Way.

Contents

Observational history

A visual band light curve for AH Scorpii, plotted from AAVSO data AHScoLightCurve.png
A visual band light curve for AH Scorpii, plotted from AAVSO data

In 1907 Henrietta Swan Leavitt and Edward Charles Pickering announced the discovery of this variable star. [11] It was given its variable star designation, AH Scorpii, in 1912. [12] The total visual magnitude range is 6.5 - 9.6. [2]

Distance

Prior to the 21st century, the distance of AH Scorpii was considered to be uncertain, between about 1.5 and 4.6 kpc. VLBI measurements of the masers have provided an accurate distance of 2,260 parsecs based on observation of SiO, H2O, and OH masers in its oxygen-rich circumstellar material. The masers were observed to be approaching the star at 13 km/s, indicating overall contraction at around phase 0.55 of the visual variations. [7] Gaia Data Release 3 includes a parallax of 0.5632±0.0799  mas , corresponding to a distance of about 1.9 kpc. [1]

Characteristics

The star is a dust-enshrouded red supergiant [13] and is classified as a semiregular variable star with a main period of 714 days. [2] No long secondary periods have been detected. [14]

Modelling of AH Scorpii near maximum light has determined an effective temperature of 3,682±190 K and a luminosity of 330,000±86,000 L☉. A radius of 1,411±124 R☉ was determined from an angular diameter of 5.81±0.15  mas and the given distance of 2.26±0.19 kpc. [5] Its angular diameter was re-measured at 5.05±0.5 mas in 2023. [15]

See also

References

  1. 1 2 3 4 5 6 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. 1 2 3 Kiss, L. L.; Szabó, Gy. M.; Bedding, T. R. (2006). "Variability in red supergiant stars: Pulsations, long secondary periods and convection noise". Monthly Notices of the Royal Astronomical Society. 372 (4): 1721–1734. arXiv: astro-ph/0608438 . Bibcode:2006MNRAS.372.1721K. doi: 10.1111/j.1365-2966.2006.10973.x . S2CID   5203133.
  3. ↑ Bowers, P. F. (December 1981). "Supergiant OH/IR stars". The Astronomical Journal . 86: 1930–1934. Bibcode:1981AJ.....86.1930B. doi:10.1086/113074. ISSN   0004-6256.
  4. 1 2 Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
  5. 1 2 3 4 5 6 Arroyo-Torres, B.; Wittkowski, M.; Marcaide, J. M.; Hauschildt, P. H. (2013). "The atmospheric structure and fundamental parameters of the red supergiants AH Scorpii, UY Scuti, and KW Sagittarii". Astronomy & Astrophysics. 554: A76. arXiv: 1305.6179 . Bibcode:2013A&A...554A..76A. doi:10.1051/0004-6361/201220920. S2CID   73575062.
  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. 1 2 Chen, Xi; Shen, Zhi-Qiang (2008). "VLBI Observations of SiO Masers around AH Scorpii". The Astrophysical Journal. 681 (2): 1574–1583. arXiv: 0803.1690 . Bibcode:2008ApJ...681.1574C. doi:10.1086/588186. S2CID   7603031.
  8. ↑ Baudry, A.; Le Squeren, A. M.; Lepine, J. R. D. (1977). "The supergiant OH stars S Per and AH SCO - Conditions for OH emission in circumstellar envelopes". Astronomy and Astrophysics. 54: 593. Bibcode:1977A&A....54..593B.
  9. ↑ González-Torà, G.; Wittkowski, M.; Davies, B.; Plez, B. (2024-03-01). "The effect of winds on atmospheric layers of red supergiants II. Modelling VLTI/GRAVITY and MATISSE observations of AH Sco, KW Sgr, V602 Car, CK Car, and V460 Car". Astronomy and Astrophysics. 683: A19. arXiv: 2312.12521 . Bibcode:2024A&A...683A..19G. doi:10.1051/0004-6361/202348047. ISSN   0004-6361.
  10. ↑ "Download Data". aavso.org. AAVSO. Retrieved 1 October 2021.
  11. ↑ Leavitt, Henrietta S.; Pickering, Edward C. (December 1907). "25 New Variable Stars in Harvard Map, Nos. 24, 36, and 42". Harvard College Observatory Circular. 135: 1–3. Bibcode:1907HarCi.135....1L . Retrieved 18 September 2025.
  12. ↑ Duner; Hartwig; Muller (June 1912). "Benennung von neu entdeckten veränderlichen Sternen". Benennung von neu entdeckten veränderlichen Sternen. 191 (19): 341–358. Bibcode:1912AN....191..341.. doi:10.1002/asna.19121911902 . Retrieved 18 September 2025.
  13. ↑ Van Loon, J. Th.; Cioni, M.-R. L.; Zijlstra, A. A.; Loup, C. (2005). "An empirical formula for the mass-loss rates of dust-enshrouded red supergiants and oxygen-rich Asymptotic Giant Branch stars". Astronomy and Astrophysics. 438 (1): 273–289. arXiv: astro-ph/0504379 . Bibcode:2005A&A...438..273V. doi:10.1051/0004-6361:20042555. S2CID   16724272.
  14. ↑ Percy, John R.; Sato, Hiromitsu (2009). "Long Secondary Periods in Pulsating Red Supergiant Stars". Journal of the Royal Astronomical Society of Canada. 103 (1): 11. Bibcode:2009JRASC.103...11P.
  15. ↑ González-Torà, G.; Wittkowski, M.; Davies, B.; Plez, B. (December 19, 2023). "The effect of winds on atmospheric layers of red supergiants II. Modelling VLTI/GRAVITY and MATISSE observations of AH Sco, KW Sgr, V602 Car, CK Car and V460 Car". Astronomy & Astrophysics. 683: A19. arXiv: 2312.12521 . Bibcode:2024A&A...683A..19G. doi:10.1051/0004-6361/202348047. ISSN   0004-6361.
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