Figure 1: Artist’s impression of a Jupiter-like planet.
If a star has a planet orbiting around it, the gravitational pull from the planet can cause the star to wobble. A sufficiently massive planet can induce a large enough “wobbling” that can be detectable through radial velocity measurements. Detecting Jupiter-like planets will require multi-year observations as these planets have long orbital periods. Using radial velocity measurements over a long time baseline of more than 10 to 15 years, Endl et al. (2015) present the discovery of two Jupiter-like planets identified as HD 95872b and HD 162004b.
HD 95872b is estimated to have at least ~4.6 times the mass of Jupiter. It orbits a K0V host star at ~5.2 AU, in an almost circular orbit, taking ~4375 days to complete an orbit. The host star of HD 95872b is estimated to be 10.0 ± 3.7 billion years old. It has 0.95 ± 0.04 times the mass of the Sun, an effective surface temperature around 5312 ± 100 K, and it is located ~25 light years away. The amplitude of the “wobbling” induced by HD 95872b on its host star is ~59 m/s. Since HD 95872b is at least a few times more massive the Jupiter, it may host Mars-sized moons.
HD 162004b is estimated to have at least ~1.53 times the mass of Jupiter. It orbits a G0V host star at ~4.43 AU, in an elongated orbit with eccentricity ~0.40, taking ~3117 days to complete an orbit. The host star of HD 162004b is estimated to be 3.3 ± 1.0 billion years old. It has 1.19 ± 0.07 times the mass of the Sun, an effective surface temperature of 6212 ± 75 K, and it is located ~70 light years away. The amplitude of the “wobbling” induced by HD 162004b on its host star is ~21 m/s.
Figure 2: Radial velocity curve indicating the presence of HD 95872b. Endl et al. (2015)
Figure 3: Radial velocity curve indicating the presence of HD 162004b. Endl et al. (2015)
Reference:
Endl et al. (2015), “Two New Long-Period Giant Planets from the McDonald Observatory Planet Search and Two Stars with Long-Period Radial Velocity Signals Related to Stellar Activity Cycles”, arXiv:1512.02965 [astro-ph.EP]