Exoplanet · Neptune-like planet
HD 219666 b
HD 219666 b is a Neptune-like planet orbiting the star HD 219666. Its year lasts 6.03 Earth days. It was discovered in 2018 by the Transit method.
| Host star | HD 219666 |
|---|---|
| Distance | 307.2 light-years (94.2 pc) |
| Orbital period | 6.03 days |
| Orbital radius | 0.0636 AU |
| Eccentricity | 0.050 |
| Radius | 4.9 R⊕ · 0.437 R♃ |
| Mass | 17.6 M⊕ · 0.0554 M♃ |
| Density | 0.87 g/cm³ |
| Surface gravity | 0.734 × Earth |
| Equilibrium temperature | 1,076 K (803 °C) |
| Stellar flux received | 598 × Earth |
| Discovery method | Transit |
| Discovery year | 2018 |
| Discovered by | Transiting Exoplanet Survey Satellite (TESS) |
Habitable zone
Inside the inner edge of the habitable zone: it receives 598 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 8.9° across: 17 times the Sun as we see it from Earth.
In the sky
A telescope is needed to see it: its apparent magnitude is 9.90. Visible from the whole Southern Hemisphere and north to latitude 33° N. South of latitude 33° S 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 1719. At the speed of Voyager 1, the fastest craft leaving the Solar System (16.9 km per second), the trip would take 5.4 million years.
Data: NASA Exoplanet Archive, PSCompPars. Its look in the simulation is a rendering based on the measured radius, mass and temperature.