sub-brown dwarf

He joined a number of astronomers who said they preferred the name sub-brown dwarf.

It is not clear whether this companion object is a sub-brown dwarf or a planet.

Objects below 13 Jupiter-mass are sometimes studied under the label "sub-brown dwarf".

A sub-brown dwarf - cold masses smaller than brown dwarfs that do not orbit a star.

One definition of a sub-brown dwarf is a planet-mass object that formed through cloud-collapse rather than accretion.

There is no consensus yet among astronomers whether to classify the object as a sub-brown dwarf (with planets) or a rogue planet (with moons).

With such a definition, if 2M1207b formed by direct gravitational collapse of a gaseous nebula, it would be classed as a sub-brown dwarf rather than a planet.

A free-floating object with a mass below 13 Jupiter masses is a "sub-brown dwarf," whereas such an object in orbit around a fusing star is a planet, even if, in all other respects, the two objects may be identical.

This formation distinction between a sub-brown dwarf and a planet is not universally agreed upon; astronomers are divided into two camps as whether to consider the formation process of a planet as part of its division in classification.

S Ori 52 is a sub-brown dwarf, or isolated planet, in the Delta Orionis cluster and is in spectral class L. It was first observed using the W. M. Keck Observatory in Mauna Kea.

The smallest mass of gas cloud that could collapse to form a sub-brown dwarf is about 1 M. This is because to collapse by gravitational contraction requires radiating away energy as heat and this is limited by the opacity of the gas.

A sub-brown dwarf is an astronomical object formed in the same manner as stars and brown dwarfs (i.e. through the collapse of a gas cloud) but that has a mass below the limiting mass for thermonuclear fusion of deuterium (about 13 Jupiter masses) and that hence is not a brown dwarf.

Free-floating sub-brown dwarfs can be observationally indistinguishable from rogue planets that originally formed around a star and were ejected from orbit, and on the other hand a sub-brown dwarf formed free-floating in a star cluster may get captured into orbit around a star.