Astronomy:Iota Octantis
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Octans |
| Right ascension | 12h 54m 58.80949s[1] |
| Declination | −85° 07′ 24.1041″[1] |
| Apparent magnitude (V) | 5.83 + 6.75[2] |
| Characteristics | |
| Spectral type | K0 III[3] |
| U−B color index | +0.79[4] |
| B−V color index | +1.02[4] |
| Astrometry | |
| Radial velocity (Rv) | 53.4±0.7[5] km/s |
| Proper motion (μ) | RA: +67.20[1] mas/yr Dec.: +24.76[1] mas/yr |
| Parallax (π) | 9.27 ± 0.46[1] mas |
| Distance | 350 ± 20 ly (108 ± 5 pc) |
| Absolute magnitude (MV) | +0.29 |
| Details[6] | |
| Mass | 2.49+1.48 −1.31 M☉ |
| Radius | 12.43[7] R☉ |
| Luminosity | 81±9 L☉ |
| Temperature | 4,890±110 K |
| Metallicity [Fe/H] | −0.3 dex |
| Rotational velocity (v sin i) | 1.9±1.3[8] km/s |
| Age | 725[9] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Iota Octantis, Latinized, from ι Octantis is a double star[10] in the southern circumpolar constellation Octans. The "A" component has an apparent magnitude of 5.83,[2] making it faintly visible to the naked eye under ideal conditions, but the "B" component can't be seen due to its faintness.[2] The system is located at a distance of 350 light years[1] based on its annual parallax shift, but is drifting away at a rate of 53.4 km/s.[5]
Iota Octantis A has a classification of K0 III,[3] which indicates that it is an evolved K-type star that exhausted hydrogen at its core and left the main sequence. It has an angular diameter of 1.07 arcseconds,[11] which yields a radius 12.43 times that of the Sun at its estimated distance.[7] At present Iota Octantis A has 2.49 times the mass of the Sun[6] and radiates at 81 times the luminosity of the Sun[6] from its enlarged photosphere at an effective temperature of 4,890 K,[6] which gives it an orangish-yellow hue. Iota Octantis is metal deficient[6] and spins slowly with a projected rotational velocity of 1.9 km/s.[8]
Eggleton et al. states that both stars have similar spectral types,[10] but there is a faint tenth magnitude companion with a classification of F8 located 60.1″ away,[12] which is unrelated to the two.
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 van Leeuwen, F. (November 2007). "Validation of the new Hipparcos reduction". Astronomy & Astrophysics 474 (2): 653–664. doi:10.1051/0004-6361:20078357. ISSN 0004-6361. Bibcode: 2007A&A...474..653V.
- ↑ 2.0 2.1 2.2 Fabricius, C.; Høg, E.; Makarov, V. V.; Mason, B. D.; Wycoff, G. L.; Urban, S. E. (March 2002). "The Tycho double star catalogue". Astronomy & Astrophysics 384 (1): 180–189. doi:10.1051/0004-6361:20011822. ISSN 0004-6361. Bibcode: 2002A&A...384..180F.
- ↑ 3.0 3.1 Houk, N.; Cowley, A. P. (1975). University of Michigan Catalogue of two-dimensional spectral types for the HD stars. Volume I. Declinations -90_ to -53_ƒ0.. Bibcode: 1975mcts.book.....H.
- ↑ 4.0 4.1 Johnson, H. L.; Mitchell, R. I.; Iriarte, B.; Wisniewski, W. Z. (January 1966). "UBVRIJKL Photometry of the Bright Stars". Communications of the Lunar and Planetary Laboratory 4: 99–110. Bibcode: 1966CoLPL...4...99J.
- ↑ 5.0 5.1 Kharchenko, N.V.; Scholz, R.-D.; Piskunov, A.E.; Röser, S.; Schilbach, E. (November 2007). "Astrophysical supplements to the ASCC-2.5: Ia. Radial velocities of ~55000 stars and mean radial velocities of 516 Galactic open clusters and associations". Astronomische Nachrichten 328 (9): 889–896. doi:10.1002/asna.200710776. ISSN 0004-6337. Bibcode: 2007AN....328..889K.
- ↑ 6.0 6.1 6.2 6.3 6.4 Charbonnel, C.; Lagarde, N.; Jasniewicz, G.; North, P. L.; Shetrone, M.; Krugler Hollek, J.; Smith, V. V.; Smiljanic, R. et al. (January 2020). "Lithium in red giant stars: Constraining non-standard mixing with large surveys in the Gaia era". Astronomy & Astrophysics 633: A34. doi:10.1051/0004-6361/201936360. ISSN 0004-6361. Bibcode: 2020A&A...633A..34C.
- ↑ 7.0 7.1 Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, 1 (3 ed.), Birkhäuser, ISBN 3-540-29692-1, https://books.google.com/books?id=OvTjLcQ4MCQC&pg=PA41. The radius (R*) is given by:
- [math]\displaystyle{ \begin{align} 2\cdot R_* & = \frac{(108\cdot 1.07\cdot 10^{-3})\ \text{AU}}{0.0046491\ \text{AU}/R_{\bigodot}} \\ & \approx 24.86\cdot R_{\bigodot} \end{align} }[/math]
- ↑ 8.0 8.1 De Medeiros, J. R.; Alves, S.; Udry, S.; Andersen, J.; Nordström, B.; Mayor, M. (January 2014). "A catalog of rotational and radial velocities for evolved stars: V. Southern stars⋆⋆⋆". Astronomy & Astrophysics 561: A126. doi:10.1051/0004-6361/201220762. ISSN 0004-6361. Bibcode: 2014A&A...561A.126D.
- ↑ "Digital Demo Room - Stellar Structure and Evolution Simulator". http://rainman.astro.illinois.edu/ddr/stellar/intermediate.html.
- ↑ 10.0 10.1 Eggleton, P. P.; Tokovinin, A. A. (11 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. ISSN 0035-8711. Bibcode: 2008MNRAS.389..869E.
- ↑ Stevens, Daniel J.; Stassun, Keivan G.; Gaudi, B. Scott (29 November 2017). "Empirical Bolometric Fluxes and Angular Diameters of 1.6 Million Tycho-2 Stars and Radii of 350,000 Stars with Gaia DR1 Parallaxes". The Astronomical Journal 154 (6): 259. doi:10.3847/1538-3881/aa957b. ISSN 0004-6256. Bibcode: 2017AJ....154..259S.
- ↑ Mason, Brian D.; Wycoff, Gary L.; Hartkopf, William I.; Douglass, Geoffrey G.; Worley, Charles E. (1 December 2001). "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog". The Astronomical Journal 122 (6): 3466–3471. doi:10.1086/323920. ISSN 0004-6256. Bibcode: 2001AJ....122.3466M.
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