HD 149026 b, formally named Smertrios /ˈsmɜːrtriɒs/, is an extrasolar planet and hot Jupiter approximately 250 light-years from the Sun in the constellation of Hercules.

HD 149026, also named Ogma /ˈɒɡmə/,[3] The 2.8766-day period planet orbits the yellow subgiant star HD 149026 at a distance of 0.042 AU (3.9 million mi; 6.3 million km) and is notable first as a transiting planet, and second for a small measured radius (relative to mass and incoming heat) that suggests an exceptionally large planetary core.

In July 2014, the International Astronomical Union launched NameExoWorlds, a process for giving proper names to certain exoplanets and their host stars.

After the planet was first detected from the Doppler effect it caused in the light of the host star, it was studied for transits at the Fairborn Observatory.

[9] Careful radial velocity measurements have made it possible to detect the Rossiter–McLaughlin effect, the shifting in photospheric spectral lines caused by the planet occulting a part of the rotating stellar surface.

[13] Its day-side brightness temperature was subsequently directly measured as 2,300 ± 200 K by comparing the combined emissions of star and planet at 8 μm wavelength before and during a transit event.

[21] As a result, the planet has been described as a "super-Neptune", in analogy to the core-dominated outer ice giants of the Solar System, though whether the core of HD 149026 b is mainly icy or rocky is not currently known.

[18] Robert Naeye in Sky & Telescope claimed "it contains as much or more metals than all the planets and asteroids in our solar system combined".

[1] One possibility is that because the planet orbits so close to its star, it is — unlike Jupiter — ineffective in cleansing the planetary system of rocky bodies.