Astronomy:Nu Octantis
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Short description: Star in the constellation Octans
  | |
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Octans |
| Right ascension | 21h 41m 28.64977s[1] |
| Declination | −77° 23′ 24.1563″[1] |
| Apparent magnitude (V) | 3.73[2] |
| Characteristics | |
| Spectral type | K1III[3] |
| U−B color index | +0.89[4] |
| B−V color index | +1.00[4] |
| Astrometry | |
| Radial velocity (Rv) | +34.40[5] km/s |
| Proper motion (μ) | RA: +66.41[1] mas/yr Dec.: −239.10[1] mas/yr |
| Parallax (π) | 51.5172 ± 0.6525[6] mas |
| Distance | 63.3 ± 0.8 ly (19.4 ± 0.2 pc) |
| Absolute magnitude (MV) | +2.10[2] +2.02[7] |
| Orbit[7] | |
| Period (P) | 1050.69+0.05 −0.07 d |
| Semi-major axis (a) | 2.62959+0.00009 −0.00011 AU |
| Eccentricity (e) | 0.23680±0.00007 |
| Inclination (i) | 70.8±0.9° |
| Longitude of the node (Ω) | 87±1.2° |
| Argument of periastron (ω) (secondary) | 74.970±0.016° |
| Semi-amplitude (K1) (primary) | 7.032±0.003 km/s |
| Details | |
| Nu Octantis A | |
| Mass | 1.04[8] 1.61[7] M☉ |
| Radius | 5.9[8] 5.81±0.12[7] R☉ |
| Luminosity | 17.53[2] L☉ |
| Surface gravity (log g) | 3.12±0.10[7] cgs |
| Temperature | 4,860±40[9] K |
| Metallicity [Fe/H] | +0.18±0.04[7] dex |
| Rotational velocity (v sin i) | 2.0[7] km/s |
| Age | ~2.5-3[7] Gyr |
| Nu Octantis B[10] | |
| Mass | 0.585[7] M☉ |
| Other designations | |
| Database references | |
| SIMBAD | data |
ν Octantis, Latinised as Nu Octantis, is the brightest star in the constellation of Octans. It is a spectroscopic binary[11] star with a period around 2.9 years.[9] Its apparent magnitude is 3.73.[2] Located around 21.20 parsecs (69.1 ly) distant,[1] the primary is an orange giant of spectral type K1III,[3] a star that has used up its core hydrogen and has expanded. The secondary star is likely either a red dwarf or a white dwarf, from its relatively low mass.[10]
Planetary system
In 2009, the system was hypothesised to contain a superjovian exoplanet based on perturbations in the orbital period.[9] A prograde solution was quickly ruled out[12] but a retrograde solution remains a possibility, although the variations may instead be due to the secondary star being itself a close binary,[13] since the formation of a planet in such a system would difficult due to dynamic perturbations.[14] Further evidence ruling out a stellar variability and favouring the existence of the planet was gathered by 2021.[10]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | 2.1059 MJ | 1.276 | 414.8 | 0.086 | 112.5° | — |
References
- ↑ 1.0 1.1 1.2 1.3 1.4 Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics 474 (2): 653–664. doi:10.1051/0004-6361:20078357. Bibcode: 2007A&A...474..653V. Vizier catalog entry
- ↑ 2.0 2.1 2.2 2.3 Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A. Vizier catalog entry
- ↑ 3.0 3.1 Gray, R. O. et al. (July 2006). "Contributions to the Nearby Stars (NStars) Project: spectroscopy of stars earlier than M0 within 40 pc-The Southern Sample". The Astronomical Journal 132 (1): 161–170. doi:10.1086/504637. Bibcode: 2006AJ....132..161G.
- ↑ 4.0 4.1 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
- ↑ Wilson, R. E. (1953). "General Catalogue of Stellar Radial Velocities". Carnegie Institute Washington D.C. Publication (Carnegie Institution for Science). Bibcode: 1953GCRV..C......0W.
- ↑ 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.
- ↑ 7.0 7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8 7.9 Ramm, D. J. (2016). "The conjectured S-type retrograde planet in ν Octantis: more evidence including four years of iodine-cell radial velocities". Monthly Notices of the Royal Astronomical Society 460 (4): 3706–3719. doi:10.1093/mnras/stw1106. Bibcode: 2016MNRAS.460.3706R.
- ↑ 8.0 8.1 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. Bibcode: 1999A&A...352..555A. Vizier catalog entry
- ↑ 9.0 9.1 9.2 Ramm, D. J.; Pourbaix, D.; Hearnshaw, J. B.; Komonjinda, S. (April 2009). "Spectroscopic orbits for K giants β Reticuli and ν Octantis: what is causing a low-amplitude radial velocity resonant perturbation in ν Oct?". Monthly Notices of the Royal Astronomical Society 394 (3): 1695–1710. doi:10.1111/j.1365-2966.2009.14459.x. Bibcode: 2009MNRAS.394.1695R.
- ↑ 10.0 10.1 10.2 Ramm, D J; Robertson, P et al. (2021). "A photospheric and chromospheric activity analysis of the quiescent retrograde-planet host ν Octantis A". Monthly Notices of the Royal Astronomical Society 502 (2): 2793–2806. doi:10.1093/mnras/stab078.
- ↑ 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.
- ↑ Eberle, J.; Cuntz, M. (October 2010). "On the reality of the suggested planet in the ν Octantis system". The Astrophysical Journal 721 (2): L168–L171. doi:10.1088/2041-8205/721/2/L168. Bibcode: 2010ApJ...721L.168E.
- ↑ Morais, M. H. M.; Correia, A. C. M. (February 2012). "Precession due to a close binary system: an alternative explanation for ν-Octantis?". Monthly Notices of the Royal Astronomical Society 419 (4): 3447–3456. doi:10.1111/j.1365-2966.2011.19986.x. Bibcode: 2012MNRAS.419.3447M.
- ↑ Gozdziewski, K.; Slonina, M.; Migaszewski, C.; Rozenkiewicz, A. (March 2013). "Testing a hypothesis of the ν Octantis planetary system". Monthly Notices of the Royal Astronomical Society 430 (1): 533–545. doi:10.1093/mnras/sts652. Bibcode: 2013MNRAS.430..533G.
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