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Iota Octantis, Latinized, from ι Octantis is a double star in the southern circumpolar constellation Octans. The "A" component has an apparent magnitude of 5.83, making it faintly visible to the naked eye under ideal conditions, but the "B" component can't be seen due to its faintness. The system is located at a distance of 350 light years based on its annual parallax shift, but is drifting away at a rate of 53.4 km/s.

Iota Octantis A has a classification of K0 III, 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, which yields a radius 12.43 times that of the Sun at its estimated distance. At present Iota Octantis A has 2.49 times the mass of the Sun and radiates at 81 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,890 K, which gives it an orangish-yellow hue. Iota Octantis is metal deficient and spins slowly with a projected rotational velocity of 1.9 km/s.

Eggleton et al. states that both stars have similar spectral types, but there is a faint tenth magnitude companion with a classification of F8 located 60.1″ away, which is unrelated to the two.

References

1. ^ van Leeuwen, F. (November 2007). "Validation of the new Hipparcos reduction". Astronomy & Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. ISSN 0004-6361.
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. Bibcode:2002A&A...384..180F. doi:10.1051/0004-6361:20011822. ISSN 0004-6361.
3. ^ 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. ^ 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. ^ 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. arXiv:0705.0878. Bibcode:2007AN....328..889K. doi:10.1002/asna.200710776. ISSN 0004-6337.
6. ^ Charbonnel, C.; Lagarde, N.; Jasniewicz, G.; North, P. L.; Shetrone, M.; Krugler Hollek, J.; Smith, V. V.; Smiljanic, R.; Palacios, A.; Ottoni, G. (January 2020). "Lithium in red giant stars: Constraining non-standard mixing with large surveys in the Gaia era". Astronomy & Astrophysics. 633: A34. arXiv:1910.12732. Bibcode:2020A&A...633A..34C. doi:10.1051/0004-6361/201936360. ISSN 0004-6361.
7. ^ Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, vol. 1 (3 ed.), Birkhäuser, ISBN 3-540-29692-1. The radius (R_*) is given by:

   ${\displaystyle {\begin{aligned}2\cdot R_{*}&={\frac {(108\cdot 1.07\cdot 10^{-3})\ {\text{AU}}}{0.0046491\ {\text{AU}}/R_{\bigodot }}}\\&\approx 24.86\cdot R_{\bigodot }\end{aligned}}}$

8. ^ 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. arXiv:1312.3474. Bibcode:2014A&A...561A.126D. doi:10.1051/0004-6361/201220762. ISSN 0004-6361.
9. "Digital Demo Room - Stellar Structure and Evolution Simulator". rainman.astro.illinois.edu. Retrieved 4 January 2022.
10. ^ 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. arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x. ISSN 0035-8711.
11. 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. arXiv:1708.05025. Bibcode:2017AJ....154..259S. doi:10.3847/1538-3881/aa957b. ISSN 0004-6256.
12. 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. Bibcode:2001AJ....122.3466M. doi:10.1086/323920. ISSN 0004-6256.

v t e Constellation of Octans
List of stars in Octans Octans in Chinese astronomy
Stars	Bayer α β γ γ γ δ ε ζ η θ ι κ λ μ μ ν ξ ο π π ρ σ (Polaris Australis) τ υ φ χ ψ ω Variable R BQ CK CW FT HR 47 512 525 4595 6837 6912 7698 7785 7812 8234 8380 8432 8526 8577 8786 8935 8957 8995 HD 142022 166066 212301 Other Gliese 877 LHS 475 TOI-4342 W2150AB
Exoplanets 2MASS J2126–8140 HD 142022 Ab HD 212301 b LHS 475 b
Galaxies	NGC 2573 7095 7098 Other PGC 10922
Category

• Octans
• K-type giants
• Henry Draper Catalogue objects
• Hipparcos objects
• Bright Star Catalogue objects
• Durchmusterung objects
• Double stars
• Gould objects