Figure 1: Artist’s impression of a gas giant planet similar to Jupiter.
As part of the Lick-Carnegie Exoplanet Survey (LCES), Meschiari et al. (2015) present the discovery of a Jupiter analogue around a Sun-like star after high precision radial velocity measurements of the star were made using the High Resolution Echelle Spectrometer (HIRES) on the Keck Observatory in Hawaii. This planet is identified as HD 32963b. It has at least 0.7 ± 0.03 times the mass of Jupiter and its orbital period is 6.49 ± 0.07 years. For comparison, the orbital period of Jupiter is 11.86 years.
A Jupiter analogue is defined as a planet with 0.3 to 3.0 times the mass of Jupiter and an orbital period between 5 to 15 years. Additionally, the planet’s orbital eccentricity has to be less than 0.3. Using this definition, only a handful of Jupiter analogues are known and the addition of HD 32963b is an important one. This discovery emphasises the importance of long-term radial velocity surveys since Jupiter analogues takes several years to orbit their host stars and long timescale observations are needed to detect them.
Figure 2: Period-eccentricity diagram of planets with 0.3 to 3.0 times the mass of Jupiter and orbital periods between 5 to 15 years. Only planets with orbital eccentricities less than 0.3 are Jupiter analogues. Meschiari et al. (2015)
Figure 3: Radial velocity curve indicating the presence of HD 32963b. Meschiari et al. (2015)
Meschiari et al. (2015), “The Lick-Carnegie Exoplanet Survey: HD32963 -- A New Jupiter Analog Orbiting a Sun-like Star”, arXiv:1512.00417 [astro-ph.EP]