Galaxy is teeming with homeless planets
Born under a wandering star…
The galaxy – and presumably, if we’re in a normal-enough galaxy, the rest of the universe – has a bit less empty space than we thought, according to a study by the Kavli Institute for Particle Astrophysics (KIPAC).
The research suggests the Milky Way could hold many millions of “nomad planets” – many thousands existing for each main-sequence star in the galaxy.
KIPAC – a joint institute of Stanford University and America’s SLAC National Accelerator Laboratory – is suggesting that nomad planets could outnumber stars in the Milky Way, by as much as 100,000:1.
Over recent years, gravitational microlensing (the refocusing of a star’s light by planets passing “in front” of them) has provided new insights into planets that don’t appear to be bound to stars.
Louis Strigari, leader of the team that reported the results to the Royal Astronomical Society, suggests that some of the planetary orphans could even retain enough heat for microbial life – if they have enough tectonic and radioactive processes to generate heat and enough atmosphere to retain it.
Most of the 500-odd exoplanets discovered in the past two decades orbit stars, but last year, astronomers turned up a dozen nomad planets that don’t orbit stars. Some may have been ejected from the solar systems in which they formed; others may need to be explained with new theories of planetary formation.
However, Strigari believes known values like the mass of the galaxy (estimated from its gravitational pull) mean it could be “teeming” with nomad planets. As new instruments like the ground-based Large Synoptic Survey Telescope and the space-based Wide-Field Infrared Survey Telescope, both of which will come into service during the 2020s, will provide the kind of observations that will drive new estimates of the number of nomads, Strigari’s paper states.
Strigari also speculates that nomad planets, if they are able to harbor life, could also provide a vector for scattering it through the galaxy. He is, however, clear that such ideas are speculative. ®
Bloody migrant planets
Coming over here, stealing all our sunshine. They should piss off back to the Orion Nebula where they came from, etc.
Does this answer some of that unexplained mass
Wasn't one reason for dark matter to explain the fact that galaxies are heavier than they look. Maybe some of it is just rock.
Re: Re: Does this answer some of that unexplained mass
Yes and No! We are talking MACHOs. But there are limits on these...
"A small proportion of dark matter may be baryonic dark matter: astronomical bodies, such as massive compact halo objects, that are composed of ordinary matter but which emit little or no electromagnetic radiation. Consistency with other observations indicates that the vast majority of dark matter in the universe cannot be baryons, and is thus not formed out of atoms. It also cannot interact with ordinary matter via electromagnetic forces; in particular, dark matter particles do not carry any electric charge."