TOI-4336 A b: Habitable Zone, 16-Day Year
Mini-neptune around TOI-4336 A
It is 2.14 times Earth's radius, closest in size to Neptune, and 3.3 times Earth's mass, at 1.87 g/cm3, less dense than Earth. A year there lasts 16.34 days, on an orbit 5 times closer to its star than Mercury is to the Sun. Its equilibrium temperature is 309 K, in the range where liquid water is possible. The host star TOI-4336 A runs at 3307 K with 0.31 times the Sun's mass.
The habitability checklist, honestly scored
Sits inside the computed habitable zone of its star. Yes.
Dense enough to be rock rather than gas, at 1.87 g/cm3. No.
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.
Radius
2.14 Earth radii
Mass
3.3 Earth masses
Equilibrium temperature
309 K (measured)
One year
16.34 days
Orbit radius
0.0849 AU
Host star
TOI-4336 A at 3307 K
Distance
74 light-years
Starlight blocked
0.360% at each transit
What you get from the shadow
The fraction of starlight blocked sets the radius against the star's.
Found by Transiting Exoplanet Survey Satellite (TESS) in 2024. TESS scans most of the sky in 27-day stretches, so it favours bright nearby stars and short orbits over the faint distant ones Kepler specialised in.
Two independent measurements sit behind this page: a dip in starlight for the size, and something else entirely for the mass. Together they make a density.
TOI-4336 A has 2 known planets. Planets in company tug on each other, and those tugs are measurable, which is how masses get pinned down without a wobble.
TOI-4336 A b sits in the habitable zone on the arithmetic alone. That says \
where it orbits, not what it is like. What would you want measured next before calling it promising?
