- Planet name: HD 208487 c
- Planet mass (J): 0.46 (compares to Earth at 0.00315)
- Planet semi-major axis (AU): 1.8 (compares to Earth at 1, compares to Mars at 1.5)
- Orbital Period (sidereal days): 908 (compares to Earth at 365.26)
- Star name: HD 208487
- Star distance: 45 parsecs (147 light years)
- Spectral type: G2V (a sun-like yellow star)
- Star mass (solar masses): 1.3 (compares to the sun at 1 solar mass)
- Star luminosity (solar luminosity): 2.3 (compares to the sun at 1.0 solar luminosity)
- Theoretical max. time star in main sequence (billion years): 3.7 (compares to sun at 10)
- Habitable zone inner radius (AU): 1.45 (compares to the sun’s at 0.95 AU)
- Habitable zone outer radius (AU): 2.08 (compares to the sun’s at 1.37 AU)
- Planet orbits in star's circumstellar habitable zone: Yes
Comments
This exoplanet is about half the mass of Jupiter, 146 times the mass of Earth, orbiting a sun-like star at 1.8 AU, nearly twice the distance that Earth orbits the sun. Slightly farther out than Mars which orbits the sun at about 1.52 AU. And Jupiter orbits at 5.20 AU. So, this planet’s orbital path is something like between Mars and Jupiter. At this distance, the host star would appear smaller in the sky, when viewed by the planet.
This planet's host star will be in its main sequence for a relatively short time (3.7 billion years). That gives the planet only 1.8 billion years of residency in the circumstellar habitable zone. Not much time. Probably just log it and set it aside.
Given the planet’s huge size, it is most certainly a gas giant half the size of Jupiter. Such a planet would have an atmosphere of turbulent gas many thousands of miles deep. Not ruling out the possibility of living things occupying an atmospheric ecosystem, but there is almost no chance for life living on any kind of hard surface. This is mostly because, on gas giants, there is no hard/well-defined boundary between the planet’s rocky center and the thick overlying atmosphere. Instead of a defined boundary, there is thousands of miles of increasing squishiness as the gasses are gradually compressed deeper down.
The good news is that a planet of this large mass is likely to be accompanied by its own collection of satellites – moons – of which we have no data. But we can imagine. If HD 208487 c has an Earth-like moon, then this world would be escorted around the star within the star’s circumstellar habitable zone.
Getting there. As this planet is 147 light years away, rockets using gravitational slings can attain speeds of over 394,736 miles per hour (NASA Parker solar probe). At that speed, it would only take 250,818 years to get there.
My visualization of HD 208487 c. The exoplanet is the gas giant in the background. This scenario considers the possibility of rocky moons orbiting the exoplanet. Image created by Tom Morris / PlanetaryBiology.com
The exoplanet as visualized by exoExplorer. This image is taken from a rocky moon in orbit of the exoplanet. You can see the exoplanet dominating the sky beyond the horizon.
The exoplanet as visualized by exoExplorer. This image is taken from a rocky moon in orbit of the exoplanet.