Confirmed exoplanet · Database record + computed analysis
TOI-3984 A b
A confirmed world orbiting TOI-3984 A, 355.1 light-years away.
A Neptune-class world
7.90 Earth radii, in the ice-giant size range. At only 44.0 Earth masses for that size, it must be substantially gas or volatile ices: puffy, not rocky.
The orbit
Its year, one full orbit, takes just 4.4 Earth days. Orbiting this tightly around a cool star, it is very likely tidally locked: one hemisphere in permanent day, the other in permanent night.
Temperature and starlight
Its equilibrium temperature (the airless-world estimate) is about 290 °C. Above water's boiling point. It receives 16.7 times the starlight Earth gets.
Its sun
Its star is a red dwarf (3,476 K surface), type M4+/-0.5: small, dim, flare-prone, and destined to outlive the Sun many times over. The system holds 2 stars, so its skies have more than one sun.
How far is that, really?
At 355 light-years, tonight's light from this system left it around the year 1670. A Voyager-speed probe would need roughly 6,283,150 years to get there.
How we found it
It was found by the transit method: the planet crosses its star's face on schedule, dimming it by a tiny, repeating fraction. The dip's depth gives the planet's size. The discovery was announced in 2023 from Transiting Exoplanet Survey Satellite (TESS).
Everything above is computed from the archive’s measured values for this planet. Where a quantity is missing, the statement is omitted rather than guessed.
About this record
The measured values come from the NASA Exoplanet Archive, and any missing value has not been determined yet; the Atlas never fills gaps with guesses. More standout worlds: Proxima b, TRAPPIST-1e, K2-18 b, 55 Cancri e, and the detection methods that found them all.