HD 11964 is a binary star system located 110 [1] light-years away from the Sun in the equatorial constellation of Cetus. It is visible in binoculars or a telescope but is too faint to be seen with the naked eye, having an apparent visual magnitude of 7.51. [2] The system is drifting closer to the Sun with a radial velocity of −9 km/s. [5] Two extrasolar planets have been confirmed to orbit the primary.
The primary, component A, is a G-type main-sequence star with a stellar classification of G9VCN+1. [3] The suffix notation indicates an overabundance of the cyano radical in the spectrum. Houk and Swift (1999) found a class of G8IV, suggesting it is instead a more evolved subgiant star. [10] It is around seven [6] billion years old and is spinning slowly with a projected rotational velocity of 1.5 km/s. [5] The star has 1.1 [6] times the mass of the Sun and 2.2 [7] times the Sun's radius. It is radiating 2.9 [6] times the luminosity of the Sun from its photosphere at an effective temperature of 5,321 K. [5]
A wide binary companion star was discovered in 2000. [11] This secondary, designated component B, has a visual magnitude of 11.11 and lies at an angular separation of 29.7 ″ along a position angle of 134°, as of 2015. [12] It is a red dwarf with a class of M0V, [4] and has just 0.6 times the Sun's radius. It is radiating 0.085 times the Sun's luminosity at an effective temperature of 4,033 K. [1]
In August 2005, two planets were discovered orbiting the star, the innermost like Neptune and another like Jupiter orbiting at 3.34 AU. However, the second planet ( HD 11964 b) was not confirmed until May 2007. In September 2007, P.C. Gregory claimed that there was a third planet in the system on the basis of Bayesian analysis of the radial velocity data. The planet was claimed to have a mass similar to that of Saturn and located in a 360-day orbit. Gregory cautioned that the close match between the period of this planet to being exactly a year meant that the radial velocity variations may have been caused by insufficient correction for the motion of the Earth in orbit around the Sun. [13] The planet was not detected in re-reduced data in an analysis published in the Astrophysical Journal in 2009. [14]
Companion (in order from star) |
Mass |
Semimajor axis ( AU) |
Orbital period ( days) |
Eccentricity | Inclination | Radius |
---|---|---|---|---|---|---|
c | ≥ 0.11 MJ | 0.229 | 37.82 | 0.15 | — | — |
b | ≥ 0.61±0.1 MJ | 3.34±0.4 | 2,110±70 | 0.06±0.2 | — | — |
HD 11964 is a binary star system located 110 [1] light-years away from the Sun in the equatorial constellation of Cetus. It is visible in binoculars or a telescope but is too faint to be seen with the naked eye, having an apparent visual magnitude of 7.51. [2] The system is drifting closer to the Sun with a radial velocity of −9 km/s. [5] Two extrasolar planets have been confirmed to orbit the primary.
The primary, component A, is a G-type main-sequence star with a stellar classification of G9VCN+1. [3] The suffix notation indicates an overabundance of the cyano radical in the spectrum. Houk and Swift (1999) found a class of G8IV, suggesting it is instead a more evolved subgiant star. [10] It is around seven [6] billion years old and is spinning slowly with a projected rotational velocity of 1.5 km/s. [5] The star has 1.1 [6] times the mass of the Sun and 2.2 [7] times the Sun's radius. It is radiating 2.9 [6] times the luminosity of the Sun from its photosphere at an effective temperature of 5,321 K. [5]
A wide binary companion star was discovered in 2000. [11] This secondary, designated component B, has a visual magnitude of 11.11 and lies at an angular separation of 29.7 ″ along a position angle of 134°, as of 2015. [12] It is a red dwarf with a class of M0V, [4] and has just 0.6 times the Sun's radius. It is radiating 0.085 times the Sun's luminosity at an effective temperature of 4,033 K. [1]
In August 2005, two planets were discovered orbiting the star, the innermost like Neptune and another like Jupiter orbiting at 3.34 AU. However, the second planet ( HD 11964 b) was not confirmed until May 2007. In September 2007, P.C. Gregory claimed that there was a third planet in the system on the basis of Bayesian analysis of the radial velocity data. The planet was claimed to have a mass similar to that of Saturn and located in a 360-day orbit. Gregory cautioned that the close match between the period of this planet to being exactly a year meant that the radial velocity variations may have been caused by insufficient correction for the motion of the Earth in orbit around the Sun. [13] The planet was not detected in re-reduced data in an analysis published in the Astrophysical Journal in 2009. [14]
Companion (in order from star) |
Mass |
Semimajor axis ( AU) |
Orbital period ( days) |
Eccentricity | Inclination | Radius |
---|---|---|---|---|---|---|
c | ≥ 0.11 MJ | 0.229 | 37.82 | 0.15 | — | — |
b | ≥ 0.61±0.1 MJ | 3.34±0.4 | 2,110±70 | 0.06±0.2 | — | — |