Two more planets found: a 1.4-Jupiters one and a 5-Jupiters one
Two more extrasolar planets were added to the list this week, in a paper by astronomer Mercedes López-Morales and a team of coworkers with the N2K Doppler planet search program. Using the 6.5 m Magellan Telescopes at Las Campanas Observatory, Chile, the researchers found a gas giant with about 1.4 Jupiter masses around the yellow star HD 205739, and another gas giant with about five Jupiter masses in orbit around another yellow star, HD 154672. Both primaries are similar to the Sun, but with slightly higher metal concentrations.
Are either of these systems likely abodes for life? The smaller planet’s star (HD 205739) is only 2 billion years old, which is enough time for microbes, if everything else is favorable. But the giant planet there is in a very elliptical orbit, with a year shorter than Venus’. Whatever terrestrial planets might have existed in the star’s habitable zone were probably long ago destroyed by that giant spiralling past all the time.
The larger planet orbits the more metal-rich of the two stars (HD 154672), and is about 9 billion years old, or roughly twice the age of our solar system. HD 154672 have formed with about twice as much metallic and rocky raw material around it as our Sun, making it particularly likely to have terrestrial (rocky) planets. The age of that system is interesting, too. Nine billion years is a long time for any biospheres there to evolve. But… the five-Jupiter monster there bowls through the habitable zone, too. If life-worlds were there once, they’re probably gone now.
There’s still hope for life. Any large gas giant can have its own bevvy of large moons, and both these gas giants plow through their stars’ habitable zones. With higher metallicity stars there is more rock to pass around, so moons around either giant might have enough rocky elements and volatiles to make them interesting. The climates of those moons would be pretty chaotic, though.
They might harbor life. They might also be desiccated husks of shattered rock.