We present confirmation of the planetary nature of PH-2b , as well as the first mass estimates for the two planets in the Kepler-103 system .
PH-2b and Kepler-103c are both long-period and transiting , a sparsely-populated category of exoplanet .
We use Kepler light-curve data to estimate a radius , and then use HARPS-N radial velocities to determine the semi-amplitude of the stellar reflex motion and , hence , the planet mass .
For PH-2b we recover a 3.5- \sigma mass estimate of M _ { p } = 109 ^ { +30 } _ { -32 } M _ { \oplus } and a radius of R _ { p } = 9.49 \pm 0.16 R _ { \oplus } .
This means that PH-2b has a Saturn-like bulk density and is the only planet of this type with an orbital period P > 200 days that orbits a single star .
We find that Kepler-103b has a mass of M _ { \text { p,b } } = 11.7 ^ { +4.31 } _ { -4.72 } M _ { \oplus } and Kepler-103c has a mass of M _ { \text { p,c } } = 58.5 ^ { +11.2 } _ { -11.4 } M _ { \oplus } .
These are 2.5 \sigma and 5 \sigma results , respectively .
With radii of R _ { \text { p,b } } = 3.49 ^ { +0.06 } _ { -0.05 } R _ { \oplus } , and R _ { \text { p,c } } = 5.45 ^ { +0.18 } _ { -0.17 } R _ { \oplus } , these results suggest that Kepler-103b has a Neptune-like density , while Kepler-103c is one of the highest density planets with a period P > 100 days .
By providing high-precision estimates for the masses of the long-period , intermediate-mass planets PH-2b and Kepler-103c , we increase the sample of long-period planets with known masses and radii , which will improve our understanding of the mass-radius relation across the full range of exoplanet masses and radii .