Confirmed exoplanet · Database record + computed analysis
HD 28109 d
A confirmed world orbiting HD 28109, 455.3 light-years away.
A sub-Neptune
3.11 Earth radii, likely a rocky core under a thick gas or steam envelope rather than a walkable surface. At only 5.8 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 84.3 Earth days.
Temperature and starlight
Its equilibrium temperature (the airless-world estimate) is about 288 °C. Above water's boiling point. It receives 17.4 times the starlight Earth gets.
Its sun
Its star is hotter than the Sun (6,189 K, F8), burning brighter and faster. It shares the system with 2 other known planets.
How far is that, really?
At 455 light-years, tonight's light from this system left it around the year 1570. A Voyager-speed probe would need roughly 8,056,325 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 2022 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.