:INFO
Super-earth around K2-3
It is 1.46 times Earth's radius, closest in size to Earth, and 2.2 times Earth's mass. A year there lasts 44.56 days, on an orbit 2 times closer to its star than Mercury is to the Sun. Its equilibrium temperature is 305 K, in the range where liquid water is possible. The host star K2-3 runs at 3844 K with 0.55 times the Sun's mass.

:CHECKLIST
What this planet has and has not got
[ ] Inside the habitable zone, computed from the star's luminosity. Yes.
[ ] A measured mass, not just a radius. Yes.
[ ] A measured temperature rather than one derived from the star. Yes.
[ ] Any detection of an atmosphere. Not recorded in the archive.

:JOURNEY
K2-3 from the inside out
1 0.075 AU
2 0.136 AU
3 0.201 AU

:STATS
[icon:TARGET] Radius | 1.46 Earth radii
[icon:CHART] Mass | 2.2 Earth masses
[icon:FIRE] Equilibrium temperature | 305 K (measured)
[icon:CLOCK] One year | 44.56 days
[icon:BOLT] Orbit radius | 0.2014 AU
[icon:STAR] Host star | K2-3 at 3844 K
[icon:USERS] Distance | 144 light-years
[icon:TRENDING_DOWN] Starlight blocked | 0.060% at each transit

:PATH
What you get from the shadow
The depth of the dip is the ratio of the two discs, so the radius follows.

:NOTE
K2-3 has 3 known planets. Planets in company tug on each other, and those tugs are measurable, which is how masses get pinned down without a wobble.

:NOTE
Found by K2 in 2015, the second life of the Kepler spacecraft after two of its reaction wheels failed and it could no longer hold a fixed stare.

:NOTE
Size from the shadow, mass from elsewhere. Most transiting planets never get the second half, and without it composition stays a guess.

:THREAD

:LINK
https://exoplanetarchive.ipac.caltech.edu/overview/K2-3%20d
NASA Exoplanet Archive: the full record for K2-3 d