 A broad-band optical light curve for AV Microscopii, plotted from data published by Tabur et al. (2009) | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Microscopium |
| Right ascension | 20 41 24.66513 |
| Declination | −42° 08′ 01.6196″ |
| Apparent magnitude (V) | 6.28 (6.25 – 6.35) |
| Characteristics | |
| Spectral type | M4 III |
| B−V color index | 1.584±0.019 |
| Variable type | LC: |
| Astrometry | |
| Radial velocity (Rv) | −22.9±0.9 km/s |
| Proper motion (μ) | RA: +46.627 mas/yr Dec.: −32.891 mas/yr |
| Parallax (π) | 4.3815 ± 0.1715 mas |
| Distance | 740 ± 30 ly (228 ± 9 pc) |
| Absolute magnitude (MV) | −1.40 |
| Details | |
| Radius | 77.5+3.2 −16.4 R☉ |
| Luminosity | 849±38 L☉ |
| Temperature | 3,539+448 −70 K |
| Other designations | |
| AV Mic, CD−42°15034, HD 196829, HIP 102096, SAO 230323 | |
| Database references | |
| SIMBAD | data |
AV Microscopii is a variable star in the southern constellation of Microscopium. It is a dim, red-hued star near the lower limit of visibility to the naked eye with a baseline apparent visual magnitude of 6.28. The star is located approximately 740 light years away from the Sun, based on parallax, but is moving closer with a radial velocity of −23 km/s. It is a member of the Milky Way's old disk population.
Based upon a stellar classification of M4 III, this is an aging red giant star, having exhausted the supply of hydrogen at its core then expanded to around 78 times the Sun's radius. Earlier it had been classed as M3 II, with the luminosity class of a bright giant. Samus et al. (2017) have it tentatively classified as an irregular variable of subtype LC, suggesting this is a supergiant star. It is a pulsating variable with multiple periods discovered, ranging in apparent visual magnitude between 6.25 and 6.35. The star radiates 849 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 3,539 K.
| Period (days) | 22.3 | 23.3 | 30.3 | 31.0 | 32.3 | 45.0 | 110.7 |
| Amplitude (mag.) | 0.038 | 0.050 | 0.017 | 0.027 | 0.019 | 0.025 | 0.018 |
References
- ^ Tabur, V.; et al. (December 2009). "Long-term photometry and periods for 261 nearby pulsating M giants". Monthly Notices of the Royal Astronomical Society. 400 (4): 1945–1961. arXiv:0908.3228. Bibcode:2009MNRAS.400.1945T. doi:10.1111/j.1365-2966.2009.15588.x. S2CID 15358380.
- ^ 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.
- ^ Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. S2CID 119257644.
- ^ Samus, N. N.; et al. (2017). "General Catalogue of Variable Stars". Astronomy Reports. 5.1. 61 (1): 80–88. Bibcode:2017ARep...61...80S. doi:10.1134/S1063772917010085. S2CID 125853869.
- ^ Houk, Nancy (1978). Michigan catalogue of two-dimensional spectral types for the HD stars. Vol. 2. Ann Arbor: Dept. of Astronomy, University of Michigan. Bibcode:1978mcts.book.....H.
- "AV Mic". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-08-11.
- Eggen, O. J. (August 1976). "A sample of old-disk-population red giants". Publications of the Astronomical Society of the Pacific. 88: 426–443. Bibcode:1976PASP...88..426E. doi:10.1086/129965.
- Evans, David S.; et al. (1959). "Fundamental data for southern stars (Second List)". Monthly Notices of the Royal Astronomical Society. 119 (6): 638. Bibcode:1959MNRAS.119..638E. doi:10.1093/mnras/119.6.638.
- Watson, Christopher (28 September 2009). "AV Microscopii". AAVSO Website. American Association of Variable Star Observers. Retrieved 20 March 2015.
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