Confirmed exoplanet · Database record + computed analysis
HD 154857 b
A confirmed world orbiting HD 154857, 206.9 light-years away.
A gas giant
13.30 Earth radii, Jupiter-class (Jupiter is 11.2). At only 778.7 Earth masses for that size, it must be substantially gas or volatile ices: puffy, not rocky.
The orbit
Its year takes 409 Earth days (1.1 Earth years). The orbit is strongly stretched (eccentricity 0.46), so its distance from the star, and with it the climate, swings dramatically.
Temperature and starlight
Its equilibrium temperature (the airless-world estimate) is about 87 °C. It receives 2.8 times the starlight Earth gets.
Its sun
Its star is Sun-like (5,589 K, G5 V; the Sun is 5,772 K). It shares the system with 1 other known planet.
How far is that, really?
At 207 light-years, tonight's light from this system left it around the year 1819. A Voyager-speed probe would need roughly 3,661,311 years to get there.
How we found it
It was found by the radial-velocity method: the planet's gravity swings its star in a small circle, and that wobble shows up as a rhythmic Doppler shift in the starlight. The wobble's size gives the planet's minimum mass. The discovery was announced in 2004 from Anglo-Australian Telescope.
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.