Fulton et al. (2016) present the discovery of three
moderately-irradiated, roughly Neptune-mass planets orbiting three relatively
nearby Sun-like stars that are located no more than 80 light years away. The
three planets are identified as HD 42618 b, HD 164922 c and HD 143761 c. All
three planets were detected using the radial velocity method.
HD 42618 b has at least 15.4 ± 2.4 times the mass of Earth.
It orbits its host star at ~0.55 AU and its orbital period is 149 days. HD
42618 b receives ~3.2 times the irradiation Earth gets from the Sun and its
equilibrium temperature is ~337 K.
HD 164922 c has at least 12.9 ± 1.6 times the mass of Earth.
It orbits its host star at ~0.34 AU and its orbital period is 75 days. HD
164922 c receives ~6.3 times the irradiation Earth gets from the Sun and its
equilibrium temperature is ~401 K. Exterior to the orbit of HD 164922 c is a
previously known Saturn-mass planet.
HD 143761 c has at least 25 ± 2 times the mass of Earth. It
orbits its host star at ~0.41 AU and its orbital period is 39 days. HD 143761 c
receives ~9.9 times the irradiation Earth gets from the Sun and its equilibrium
temperature is ~448 K. Interior to the orbit of HD 143761 c is a previously
known Jupiter-mass planet.
Reference:
Fulton et al. (2016), "Three Temperate Neptunes
Orbiting Nearby Stars", arXiv:1607.00007 [astro-ph.EP]