Galaxy may swarm with 100,000 times more ‘nomad planets’ than stars

February 24, 2012

An artistic rendition of a nomad object wandering the interstellar medium (intentionally blurry to represent uncertainty about whether it has an atmosphere). A nomadic object may be an icy body akin to an object found in the outer solar system, a more rocky material akin to asteroid, or even a gas giant similar in composition to the most massive solar system planets and exoplanets. (Credit: Greg Stewart/SLAC National Accelerator Laboratory)

There may be 100,000 times more wandering “nomad planets” in the Milky Way than stars, and some may carry bacterial life, according to a new study by researchers at the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC).

If any of these nomad planets are big enough to have a thick atmosphere, they could have trapped enough heat for bacterial life to exist,” said Louis Strigari, leader of the team that reported the result in a paper submitted to the Monthly Notices of the Royal Astronomical Society.

Last year, researchers detected about a dozen nomad planets, using a technique called gravitational microlensing.

A confirmation of the estimate could lend credence to another possibility mentioned in the paper — that as nomad planets roam their starry pastures, collisions could scatter their microbial flocks to seed life elsewhere.

KIPAC is a joint institute of Stanford University and the SLAC National Accelerator Laboratory.

Ref.: Louis E. Strigari, et al., Nomads of the Galaxy, 12 Jan 2012, ArXiv 

Ref.:  Jack Singal, Nomadic Planets May Swarm the Galaxy, Tidbits from 2012, Kavli Institute for Particle Astrophysics and Cosmology, 22 Feb 2012.