Exoplanet · gas giant
51 Peg b
51 Peg b is a gas giant orbiting the star Helvetios. Its year lasts 4.23 Earth days. It was discovered in 1995 by the Radial Velocity method.
| Host star | Helvetios |
|---|---|
| Distance | 50.4 light-years (15.5 pc) |
| Orbital period | 4.23 days |
| Orbital radius | 0.052 AU |
| Eccentricity | 0.006 |
| Radius | 14.1 R⊕ · 1.26 R♃ |
| Mass | 194 M⊕ · 0.61 M♃ |
| Density | 0.38 g/cm³ |
| Surface gravity | 0.975 × Earth |
| Equilibrium temperature | 1,329 K (1,056 °C) |
| Stellar flux received | 506 × Earth |
| Discovery method | Radial Velocity |
| Discovery year | 1995 |
| Discovered by | Haute-Provence Observatory |
Habitable zone
Inside the inner edge of the habitable zone: it receives 506 times the light the Earth does, too hot to keep liquid water on its surface.
Its star in the sky
In the planet's sky its star is a disc 12° across: 23 times the Sun as we see it from Earth.
In the sky
Visible to the naked eye under a dark sky (apparent magnitude 5.45). Visible from the whole Northern Hemisphere and south to latitude 69° S. North of latitude 69° N it never sets. It stands highest at midnight in September, the best time to observe it.
Light's journey
The light you see tonight set out around the year 1976. At the speed of Voyager 1, the fastest craft leaving the Solar System (16.9 km per second), the trip would take 895 thousand years.
Data: NASA Exoplanet Archive, PSCompPars. Its look in the simulation is a rendering based on the measured radius, mass and temperature.