Gamma1 Octantis
  | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Octans |
| Right ascension | 23h 52m 06.48895s[1] |
| Declination | −82° 01′ 07.7489″[1] |
| Apparent magnitude (V) | 5.10[2] |
| Characteristics | |
| Spectral type | G7III[3] |
| U−B color index | +0.60[4] |
| B−V color index | +0.92[4] |
| Astrometry | |
| Radial velocity (Rv) | +15.4±0.1[5] km/s |
| Proper motion (μ) | RA: −48.74[1] mas/yr Dec.: −21.16[1] mas/yr |
| Parallax (π) | 12.30 ± 0.17 mas[1] |
| Distance | 265 ± 4 ly (81 ± 1 pc) |
| Absolute magnitude (MV) | 0.55[2] |
| Details | |
| Mass | 1.81[6] M☉ |
| Radius | 11[6] R☉ |
| Luminosity | 68.74[2] L☉ |
| Surface gravity (log g) | 2.64[6] cgs |
| Temperature | 5,150[7] K |
| Metallicity [Fe/H] | −0.34[8] dex |
| Rotational velocity (v sin i) | 1.8[9] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
Gamma1 Octantis, Latinized from γ1 Octantis, is a single,[10] yellow-hued star in the constellation which includes the southern celestial pole, Octans. Its apparent visual magnitude is 5.10,[2] meaning that in good conditions it is bright enough to be faintly visible to the naked eye.
Distance and proper motion[edit]
Based upon an annual parallax shift of 12.30 mas which is taken during opposing points of the Earth's orbit of the sun (with compensation for its eccentricity),[1] the star is about 265 light years away. Its (proper) motion has a net vector at present of receding from the Sun, at +15.4 km/s.[5]
Characteristics[edit]
This is an evolved G-type giant star with a stellar classification of G7 III.[3] It is a red clump star,[7] which means it is generating energy through helium fusion at its core. The star has an estimated 1.81[6] times the mass of the Sun and it has expanded to 11[6] times the Sun's radius. It is radiating 69[2] times the Sun's luminosity from its enlarged photosphere at an effective temperature of 5,150 K.[7]
Gap between stars sharing Gamma designation[edit]
The very similar brightness and potentially close stars of Gamma2, 3 have been examined by the Gaia space telescope/observatory. Gamma2 is much more distant than the other two whose margins of error overlap when parallaxes are considered — they may thus be close enough to be in loose mutual orbital. These distances from our star system per Gaia's second Data Release (DR2) are, respectively, around 319 ± 5 ly and 259 ± 3 ly. The observation refines Gamma1 as being 262 ± 4 ly away.
References[edit]
- ^ a b c d e f Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600. Vizier catalog entry
- ^ a b c d e 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. Vizier catalog entry
- ^ a b Hoffleit, D.; Warren, W. H. (1995). "VizieR Online Data Catalog: Bright Star Catalogue, 5th Revised Ed. (Hoffleit+, 1991)". VizieR On-line Data Catalog: V/50. Originally Published in: 1964BS....C......0H. 5050. Bibcode:1995yCat.5050....0H.
- ^ a b Mallama, A. (2014). "Sloan Magnitudes for the Brightest Stars". The Journal of the American Association of Variable Star Observers. 42 (2): 443. Bibcode:2014JAVSO..42..443M.Vizier catalog entry
- ^ a b 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 c d e Allende Prieto, C.; Lambert, D. L. (1999). "Fundamental parameters of nearby stars from the comparison with evolutionary calculations: Masses, radii and effective temperatures". Astronomy and Astrophysics. 352: 555–562. arXiv:astro-ph/9911002. Bibcode:1999A&A...352..555A. Vizier catalog entry
- ^ a b c Gontcharov, G. A. (2009). "Red giant clump in the Tycho-2 catalogue". Astronomy Letters. 34 (11): 785–796. arXiv:1607.00619. Bibcode:2008AstL...34..785G. doi:10.1134/S1063773708110078. S2CID 73524157. Vizier catalog entry
- ^ Soubiran, Caroline; Le Campion, Jean-François; Brouillet, Nathalie; Chemin, Laurent (2016). "The PASTEL catalogue: 2016 version". Astronomy & Astrophysics. 591: A118. arXiv:1605.07384. Bibcode:2016A&A...591A.118S. doi:10.1051/0004-6361/201628497. S2CID 119258214.
- ^ De Medeiros, J. R.; Alves, S.; Udry, S.; Andersen, J.; Nordström, B.; Mayor, M. (2014). "A catalog of rotational and radial velocities for evolved stars". Astronomy & Astrophysics. 561: A126. arXiv:1312.3474. Bibcode:2014A&A...561A.126D. doi:10.1051/0004-6361/201220762. S2CID 54046583. Vizier catalog entry
- ^ 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. arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x. S2CID 14878976.
