Mu2 Octantis (μ2 Oct) is a binary star system of two G-type main-sequence stars. It shares the designation μ with μ1 Octantis, from which it is separated by 50 arcminutes.
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Octans |
| Right ascension | 20h 41m 44.102s[1] |
| Declination | −75° 21′ 02.88″[1] |
| Apparent magnitude (V) | +6.51[2] |
| Characteristics | |
| Spectral type | G1V[3] |
| U−B color index | +0.26[4] |
| B−V color index | +0.62[4] |
| Astrometry | |
| Radial velocity (Rv) | −10.90±0.2[5] km/s |
| Proper motion (μ) | RA: 156.404[1] mas/yr Dec.: −162.214[1] mas/yr |
| Parallax (π) | 25.0327 ± 0.0205 mas[1] |
| Distance | 130.3 ± 0.1 ly (39.95 ± 0.03 pc) |
| Absolute magnitude (MV) | 3.28[3] |
| Details[3] | |
| Mass | 1.29±0.08 M☉ |
| Radius | 1.73±0.21 R☉ |
| Luminosity | 3.73 L☉ |
| Surface gravity (log g) | 4.24±0.03 cgs |
| Temperature | 6,017±46 K |
| Metallicity [Fe/H] | +0.18±0.04 dex |
| Rotation | 26±3 days |
| Rotational velocity (v sin i) | 1.45 km/s |
| Age | 3.3±0.6 Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
Mu2 Octantis has a 29% higher mass than the sun, and is slightly hotter. Its radius is 73% more than the Sun's and it is nearly four times as luminous.
This star is a member of a wider binary star system. The two components are gravitationally bound and separated at 17 arcseconds in our sky, corresponding to 740 astronomical units (AU). The semimajor axis of the stars' orbit is 932 AU.[3] The companion star is HD 196068,[6] another G-type main-sequence star with an apparent magnitude of 7.18.[3]
Planetary system
editFrom 1998 to 2012, the system was observed using the CORALIE instrument, at the ESO's La Silla Observatory.[3]
In November 2012, a long-period, wide-orbiting planet was deduced by radial velocity around HD 196067. The planet has been pulled to an eccentric orbit by the B star HD 196068. The planet's true mass, as measured by astrometry, is 12.5 MJ, placing it right on the boundary between planets and brown dwarfs.[7]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (years) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | 12.5+2.5 −1.8 MJ |
5.10+0.22 −0.17 |
9.88+0.63 −0.43 |
0.70+0.14 −0.12 |
41.2+28 −9.1° |
— |
References
edit- ^ a b c d e Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
- ^ "* mu.02 Oct". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 5 August 2017.
- ^ a b c d e f Marmier, M.; et al. (2013). "The CORALIE survey for southern extrasolar planets XVII. New and updated long period and massive planets". Astronomy and Astrophysics. 551. A90. arXiv:1211.6444. Bibcode:2013A&A...551A..90M. doi:10.1051/0004-6361/201219639. S2CID 59467665.
- ^ a b Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
- ^ 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.
- ^ "HD 196068". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 5 August 2017.
- ^ a b Li, Yiting; Brandt, Timothy D.; Brandt, G. Mirek; Dupuy, Trent J.; Michalik, Daniel; Jensen-Clem, Rebecca; Zeng, Yunlin; Faherty, Jacqueline; Mitra, Elena L. (2021). "Precise Masses and Orbits for Nine Radial-velocity Exoplanets". The Astronomical Journal. 162 (6): 266. arXiv:2109.10422. Bibcode:2021AJ....162..266L. doi:10.3847/1538-3881/ac27ab. S2CID 237592581.