Astronomy:Alpha Octantis
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Octans |
| Right ascension | 21h 04m 43.06347s[2] |
| Declination | −77° 01′ 25.5735″[2] |
| Apparent magnitude (V) | 5.13[3] |
| Characteristics | |
| Spectral type | F4III + F5III (spectroscopic binary)[4] |
| U−B color index | +0.13[5] |
| B−V color index | +0.490±0.008[3] |
| Variable type | EB[6] |
| Astrometry | |
| Radial velocity (Rv) | 85.9±1.5[3] km/s |
| Proper motion (μ) | RA: +22.5215[2] mas/yr Dec.: −369.325[2] mas/yr |
| Parallax (π) | 22.5215 ± 0.0955[2] mas |
| Distance | 144.8 ± 0.6 ly (44.4 ± 0.2 pc) |
| Absolute magnitude (MV) | 1.93±0.02[7] |
| Orbit[4] | |
| Period (P) | 9.073 d |
| Eccentricity (e) | 0.39 |
| Periastron epoch (T) | 2,435,302.404 |
| Argument of periastron (ω) (secondary) | 276° |
| Semi-amplitude (K1) (primary) | 47 km/s |
| Semi-amplitude (K2) (secondary) | 47 km/s |
| Details | |
| Mass | 1.42[8] M☉ |
| Radius | 3.69[9] R☉ |
| Temperature | 6,270[7] K |
| Metallicity [Fe/H] | 0.07[7] dex |
| Rotational velocity (v sin i) | 85[10] km/s |
| Age | 1.5±0.1[7] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Alpha Octantis is a binary star[12] system in the constellation of Octans. The name is Latinized from α Octantis. Despite being labeled the "alpha" star by Lacaille, it is not the brightest star in the constellation—that title belongs to Nu Octantis. It is visible to the naked eye as a faint, yellow-white-hued point of light with an overall apparent visual magnitude of approximately 5.13.[3] The system is located approximately 148 light-years away from the Sun based on parallax.
This is a double-lined spectroscopic binary star which consists of two similar giant stars, each with spectral type F, orbiting each other with a period of just over 9 days and an eccentricity of 0.39.[4] The pair form a Beta Lyrae-type eclipsing binary system, dropping by magnitude 0.04 during the primary eclipse.[6] This system is a bright X-ray source with a luminosity of 22.78×1029 ergs s−1.[13] The system displays an infrared excess suggesting the presence of two debris disks; the first has a temperature of 450 K and is orbiting at a distance of 1.40 astronomical unit|AU from its host star, while the second is a much cooler 40 K and orbits 187.8 AU from the system.[9]
References
- ↑ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. https://mast.stsci.edu/portal/Mashup/Clients/Mast/Portal.html.
- ↑ 2.0 2.1 2.2 2.3 2.4 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G. Gaia DR2 record for this source at VizieR.
- ↑ 3.0 3.1 3.2 3.3 Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A.
- ↑ 4.0 4.1 4.2 The double-lined binary alpha Octantis, William Buscombe and Pamela M. Morris, The Observatory 80 (February 1960), pp. 28–29, Bibcode: 1960Obs....80...28B.
- ↑ HR 8021, database entry, The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version), D. Hoffleit and W. H. Warren, Jr., CDS ID V/50. Accessed on line September 4, 2008.
- ↑ 6.0 6.1 Samus', N. N et al. (2017). "General catalogue of variable stars". Astronomy Reports. 5.1 61 (1): 80. doi:10.1134/S1063772917010085. Bibcode: 2017ARep...61...80S.
- ↑ 7.0 7.1 7.2 7.3 Nordström, B. (2004). "The Geneva-Copenhagen survey of the Solar neighbourhood. Ages, metallicities, and kinematic properties of ˜14 000 F and G dwarfs". Astronomy and Astrophysics 418: 989–1019. doi:10.1051/0004-6361:20035959. Bibcode: 2004A&A...418..989N.
- ↑ Tokovinin, A. et al. (May 2006), "Tertiary companions to close spectroscopic binaries", Astronomy and Astrophysics 450 (2): 681–693, doi:10.1051/0004-6361:20054427, Bibcode: 2006A&A...450..681T
- ↑ 9.0 9.1 Cotten, Tara H.; Song, Inseok (July 2016), "A Comprehensive Census of Nearby Infrared Excess Stars", The Astrophysical Journal Supplement Series 225 (1): 24, doi:10.3847/0067-0049/225/1/15, 15, Bibcode: 2016ApJS..225...15C.
- ↑ van Belle, Gerard T. (March 2012). "Interferometric observations of rapidly rotating stars". The Astronomy and Astrophysics Review 20 (1): 51. doi:10.1007/s00159-012-0051-2. Bibcode: 2012A&ARv..20...51V.
- ↑ "* alf Oct". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=%2A+alf+Oct.
- ↑ Eggleton, P. P.; Tokovinin, A. A. (September 2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society 389 (2): 869–879. doi:10.1111/j.1365-2966.2008.13596.x. Bibcode: 2008MNRAS.389..869E.
- ↑ Makarov, Valeri V. (October 2003), "The 100 Brightest X-Ray Stars within 50 Parsecs of the Sun", The Astronomical Journal 126 (4): 1996–2008, doi:10.1086/378164, Bibcode: 2003AJ....126.1996M.
External links
- Alpha Octantis, Jim Kaler, Stars.
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