Astronomy:Nu2 Canis Majoris
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| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Canis Major |
| Right ascension | 06h 36m 41.038s[1] |
| Declination | −19° 15′ 21.17″[1] |
| Apparent magnitude (V) | 3.96[2] |
| Characteristics | |
| Evolutionary stage | Red-giant branch[3] |
| Spectral type | K1 III[2] |
| Astrometry | |
| Radial velocity (Rv) | +2.57±0.14[4] km/s |
| Proper motion (μ) | RA: +62.660[1] mas/yr Dec.: −69.816[1] mas/yr |
| Parallax (π) | 48.8490 ± 0.1323[1] mas |
| Distance | 66.8 ± 0.2 ly (20.47 ± 0.06 pc) |
| Absolute magnitude (MV) | 2.47[2] |
| Details | |
| Mass | 1.439±0.047[5] M☉ |
| Radius | 5.198±0.060[5] R☉ |
| Luminosity | 13.2±0.7[5] L☉ |
| Surface gravity (log g) | 3.165±0.005[5] cgs |
| Temperature | 4,790±27[6] K |
| Metallicity [Fe/H] | 0.21±0.10[6] dex |
| Rotational velocity (v sin i) | 1.97±0.23[4] km/s |
| Age | 4.6±0.7[6] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Nu2 Canis Majoris is a star in the southern constellation of Canis Major. Its name is a Bayer designation that is Latinized from ν2 Canis Majoris, and abbreviated Nu2 CMa or ν2 CMa. With an apparent visual magnitude of 3.96,[2] it is bright enough to be seen with the naked eye, close to Sirius. An annual parallax shift of around 50.63 mas, as measured by the Gaia spacecraft,[1] implies a distance of 66.8 light-years (20.5 pc). It is drifting further away with a line of sight velocity of +2.6 km/s.[4] The star has two confirmed exoplanets[3] and no known stellar companion.[8]
This is an aging giant star with a stellar classification of K1 III,[2] having exhausted the hydrogen at its core then expanded. It is believed to be on the early ascent of the red giant branch and has not yet undergone helium flash.[3] This star is around 4.6 billion years old[6] and is spinning slowly with a projected rotational velocity of 2 km/s.[4] It has 1.4 times the mass of the Sun and has grown to 5.2 times the Sun's radius. The star is radiating 13 the luminosity of the Sun[5] from its photosphere at an effective temperature of 4,790 K.[6]
Planetary system
By measuring periodic variations in the radial velocity of the host star between 2009 and 2010, the Pan-Pacific Planet Search program was able to identify a planet orbiting Nu2 Canis Majoris. An orbital fit produced a minimum mass estimate of 2.6±0.6 |♃|J}}}}}} with an orbital period of 2.1 years and an eccentricity of 0.23. Star spots were ruled out as a source for the signal with a false-alarm probability of 98.7%.[9] Further observations through 2019 detected the planet, as well as a secondary planet c in a 4:3 orbital resonance with planet b.[3]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | ≥1.940±0.064 MJ | 1.800±0.033 | 736.9 | 0.055 | — | — |
| c | ≥0.912±0.067 MJ | 2.205±0.046 | 988.9 | 0.046 | — | — |
Chinese name
In Chinese astronomy, ν2 Canis Majoris is called 野雞, Pinyin: Yějī, meaning Wild Cockerel, because this star is marking itself and stand alone in Wild Cockerel asterism, Well mansion (see : Chinese constellation).[10] 野雞 (Yějī), westernized into Ya Ke. According to R. H. Allen, the name Ya Ke is an asterism consisting ο1 Canis Majoris and π Canis Majoris, with other small stars in the body of the Dog.[11]
Notes
References
- ↑ 1.0 1.1 1.2 1.3 1.4 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940 Gaia DR3 record for this source at VizieR.
- ↑ 2.0 2.1 2.2 2.3 2.4 Setiawan, J. et al. (July 2004). "Precise radial velocity measurements of G and K giants. Multiple systems and variability trend along the Red Giant Branch". Astronomy and Astrophysics 421: 241–254. doi:10.1051/0004-6361:20041042-1. Bibcode: 2004A&A...421..241S.
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 Luque, R. et al. (October 13, 2019). "Precise radial velocities of giant stars XIII. A second Jupiter orbiting in 4:3 resonance in the 7 CMa system". Astronomy & Astrophysics A136: 631. doi:10.1051/0004-6361/201936464. Bibcode: 2019A&A...631A.136L.
- ↑ 4.0 4.1 4.2 4.3 Jofré, E. et al. (2015). "Stellar parameters and chemical abundances of 223 evolved stars with and without planets". Astronomy & Astrophysics 574: A50. doi:10.1051/0004-6361/201424474. Bibcode: 2015A&A...574A..50J.
- ↑ 5.0 5.1 5.2 5.3 5.4 5.5 5.6 Lin, Wen-Xu et al. (July 2024). "Using Asteroseismology to Calibrate the Physical Parameters of Confirmed Exoplanets and Their Evolved Host Stars". The Astronomical Journal 168 (1): 27. doi:10.3847/1538-3881/ad4ffc. ISSN 0004-6256. Bibcode: 2024AJ....168...27L.
- ↑ 6.0 6.1 6.2 6.3 6.4 Bonfanti, A. et al. (2015). "Revising the ages of planet-hosting stars". Astronomy and Astrophysics 575: A18. doi:10.1051/0004-6361/201424951. Bibcode: 2015A&A...575A..18B. http://www.aanda.org/articles/aa/full_html/2015/03/aa24951-14/aa24951-14.html.
- ↑ "nu.02 CMa". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=nu.02+CMa.
- ↑ 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.
- ↑ Wittenmyer, Robert A. et al. (2011). "The Pan-Pacific Planet Search. I. A Giant Planet Orbiting 7 CMa". The Astrophysical Journal 743 (2): 184. doi:10.1088/0004-637X/743/2/184. Bibcode: 2011ApJ...743..184W.
- ↑ Script error: The function "in_lang" does not exist. AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 16 日
- ↑ Allen, Richard Hinckley (1963). "Canis Major". Star Names — Their Lore and Meaning. https://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/Canis_Major*.html.
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