:INFO
Mini-neptune around KOI-351
It is 2.87 times Earth's radius, closest in size to Neptune. A year there lasts 59.74 days, on an orbit 1 times closer to its star than Mercury is to the Sun. Its equilibrium temperature is 519 K (derived from the star rather than measured), hotter than any desert. The host star KOI-351 runs at 6080 K with 1.20 times the Sun's mass.

:JOURNEY
KOI-351 from the inside out
1 0.074 AU
2 0.089 AU
3 0.320 AU
4 0.420 AU
5 0.480 AU

:STATS
[icon:TARGET] Radius | 2.87 Earth radii
[icon:FIRE] Equilibrium temperature | 519 K (derived)
[icon:CLOCK] One year | 59.74 days
[icon:BOLT] Orbit radius | 0.3200 AU
[icon:STAR] Host star | KOI-351 at 6080 K
[icon:USERS] Distance | 2767 light-years
[icon:TRENDING_DOWN] Starlight blocked | 0.048% at each transit

:PATH
What a crossing measures
The fraction of starlight blocked sets the radius against the star's.

:TIMELINE
🔭🪐📅
2013-01-01 | KOI-351 b, KOI-351 c, KOI-351 d, KOI-351 e, KOI-351 f
2017-01-01 | Kepler-90 i

:CHECKLIST
Known and unknown, as the archive has it
[ ] A radius from transit photometry. Yes.
[ ] A measured mass. No.
[ ] A density, which decides rock or gas. No.
[ ] An orbital distance. Yes.
[ ] A measured temperature rather than a derived one. No.
[ ] The shape of the orbit. No.

:NOTE
The archive lists no measured equilibrium temperature for this planet. The 519 K quoted here is derived from the star's output and the orbital distance, assuming a third of the light is reflected. It is an estimate from two numbers, not an observation.

:NOTE
Found by Kepler in 2013. Kepler's method needed repetition, not brightness. It could find small planets around faint stars, provided they came round quickly enough to be seen twice.

:NOTE.half
The detection is a shadow crossing a disc. Shadows have no weight, which is the whole reason the mass column is empty.

:NOTE.half
KOI-351 has 8 known planets. A crowded system is worth more than the sum of its planets: the timing of each transit constrains the others.

:THREAD

:LINK
https://exoplanetarchive.ipac.caltech.edu/overview/KOI-351%20d
Every parameter ever published for KOI-351 d, at the NASA Exoplanet Archive