I don't know how strong a magnetic field from a gas giant (or gas/ice dwarf as this planet might be classified) has to be to protect a moon from losing it's atmosphere, but it could happen.

Planet "HD 40307 e"
{
ParentBody "HD 40307"
Mass 3.5
Orbit
{
Period 0.0947843942505133470226
SemiMajorAxis 0.1886
Eccentricity 0.15
ArgOfPericen 302
}
}

Planet "HD 40307 f"
{
ParentBody "HD 40307"
Mass 5.2152
Orbit
{
Period 0.1417111567419576
SemiMajorAxis 0.247
Eccentricity 0.02
ArgOfPericen 91.2
}
}

Planet "HD 40307 g"
{
ParentBody "HD 40307"
Mass 7.0914
Orbit
{
Period 0.5415468856947296
SemiMajorAxis 0.6
Eccentricity 0.29
ArgOfPericen 354
}
}

For the moon: Havning a moon with a thick atmosphere isn't outside the realm of possibility. I don't know how strong a magnetic field from a gas giant (or gas/ice dwarf as this planet might be classified) has to be to protect a moon from losing it's atmosphere, but it could happen.

Also, despite being smaller than mars, if such a moon is at the right distance, it should get enough tidal stretching to keep its core from cooling too much and therefore, keep a magnetic field.

A rogue planet has been discovered 100 light years from Sol

Just makes you wonder what else is out there and what could have our name on it.

Possibility of 5+ planets in system!!

It was really big news back in October when astronomers discovered an Earth-sized planet whipping around Alpha Centauri B, a star in the Alpha Centauri system, the closest star system to Earth. Now, it turns out the nearest single sun-like star to us is likely also harboring planets--five of them--and one looks to be orbiting in the so-called “goldilocks zone.”

The star is known as Tau Ceti, which resides just 12 light-years away. That’s further than Alpha Centauri (at just four light-years) but the Tau Ceti finding is significant. The Alpha Centauri exoplanet orbits its star at too close a distance to harbor surface water--it’s simply too hot. The potential planet orbiting Tau Ceti, though its precise composition is unknown, looks to be a rocky planet like Earth. And it’s orbital distance is such that liquid water could exist on the planet’s surface.

Its minimum mass is just 4.3 times that of Earth, making it the smallest exoplanet to be discovered in the habitable zone of a sun-like star. And it’s worth noting here that the this planet is not yet confirmed--while it appears to exist in data collected from three different instruments, further study is needed before astronomers can declare it a known exoplanet. But if confirmed, the Tau Ceti planets would be a prime candidates for further study--and perhaps for eventual exploration.