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.
| 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 | |
| Spectral type | M4-5 Ia-Iab[3] |
| B−V color index | 2.57[4] |
| Variable type | SRc[3] |
| Astrometry | |
| Radial velocity (Rv) | −13.40±2.4[5] 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[6] pc) |
| Absolute magnitude (MV) | −5.8[7] |
| Details | |
| Mass | 20[8] M☉ |
| Radius | 1,411±124[4] R☉ |
| Luminosity | 329,000±86,000[4] L☉ |
| Surface gravity (log g) | −0.5[4] cgs |
| Temperature | 3,682[4] K |
| Other designations | |
| Database references | |
| SIMBAD | data |
Distance
editThe distance of AH Scorpii is considered to be uncertain. 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.[6]
Characteristics
edit
AH Scorpii is a dust-enshrouded red supergiant[10] and is classified as a semiregular variable star with a main period of 714 days. The total visual magnitude range is 6.5 - 9.6.[2] No long secondary periods have been detected.[11] 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.[4] Its angular diameter was re-measured at 5.05±0.5 mas in 2023.[12]
See also
editNotes
editReferences
edit- ^ a b c d e Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
- ^ a b 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.
- ^ a b 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.
- ^ a b c d e f 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.
- ^ 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.
- ^ a b 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.
- ^ 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.
- ^ 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.
- ^ "Download Data". aavso.org. AAVSO. Retrieved 1 October 2021.
- ^ 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.
- ^ 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.
- ^ 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.