| |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Canis Major |
| Right ascension | 06h36m 41.03758s[1] |
| Declination | −19° 15′ 21.1659″[1] |
| Apparent magnitude (V) | 3.96[2] |
| Characteristics | |
| Spectral type | K1 III[2] |
| Astrometry | |
| Radial velocity (Rv) | +2.57±0.14[3] km/s |
| Proper motion (μ) | RA: +62.57±0.15[1] mas/yr Dec.: −69.97±0.16[1] mas/yr |
| Parallax (π) | 50.63 ± 0.23 mas[1] |
| Distance | 64.4 ± 0.3 ly (19.75 ± 0.09 pc) |
| Absolute magnitude (MV) | 2.47[2] |
| Details[4] | |
| Mass | 1.3±0.1 M☉ |
| Radius | 4.9±0.1 R☉ |
| Luminosity | 11.3±0.1 L☉ |
| Surface gravity (log g) | 3.18±0.03 cgs |
| Temperature | 4,790±27 K |
| Metallicity [Fe/H] | 0.21±0.10 dex |
| Rotational velocity (v sin i) | 1.97±0.23[3] km/s |
| Age | 4.6±0.7 Gyr |
| Other designations | |
ν2 CMa, 7 CMa, BD−19°1502, FK5 2510, GC 8624, GJ 239.1, HD 47205, HIP 31592, HR 2429, SAO 151702 | |
| Database references | |
| SIMBAD | data |
Nu2 Canis Majoris (ν2 Canis Majoris) is a single[5] star in the southern constellationofCanis Major. It is a cool giant with two confirmed exoplanets.
With an apparent visual magnitude of 3.96,[2] it is bright enough to be seen with the naked eye to the southwest of Sirius. It has an annual parallax shift of around 50.63 mas as seen from Earth,[1] thus this system is about 64.4 light years from the Sun, a parallax well within the error margins of the figure later given by the Gaia space observatory data release 2, namely 50.471 ± 0.4168.[6]
It is an evolved K-type giant around 4.6 billion years old. Around 1.3 times as massive as the Sun, it has expanded to around 4.9 times the Sun's diameter and 11 times its luminosity.[4] In 2011, it was found to have a planet.[7]
InChinese 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).[8] 野雞 (Yějī), westernized into Ya Ke. According to R.H. Allen opinion, the name Ya Ke is asterism consisting ο1 Canis Majoris and π Canis Majoris, with other small stars in the body of the Dog[9]
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 MJwith 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%.[7] Further observations through 2019 detected the planet, as well as a secondary planet c in a 4:3 orbital resonance with planet b.[10]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | ≥1.895 MJ | 1.761 | 736.9 | 0.055 | — | — |
| c | ≥0.609 MJ | 2.143 | 988.9 | 0.046 | — | — |
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