Many of the planetary characteristics of Anubis such as, size, mass, and composition have much in
common with a brown dwarf, a star that didn't have enough mass to sustain fusion in its core.
In general, a gas giant between 10MJ and 84MJ would be regarded as a brown
dwarf. Put simply, a
brown dwarf is formed by exactly the same process as a star. A brown dwarf can shine by generating
its own light, if it is very massive, by the heat generated in its core due to gravitational
compression. Some of the largest brown dwarfs are believed to have had a period of nuclear fusion
in the core that couldn't be sustained for very long. Theoretically, a giant planet of similar
composition to Jupiter could also become a star if it were massive enough.
Several key differences indicate Anubis to be a "super planet", a gas giant more massive than Jupiter.
Primarily, a star doesn't have a core of rock. When a star forms, its core is mostly hydrogen.
The question is how can you tell if there is a core of rock in a giant like Anubis.
There are several indicators that show this is probable. First, the orbit is thought to provide
clues. Secondly, the position of the planet in the system is important.
To understand the significance of these points, it is helpful to briefly describe how stars and
planets form to become a solar system. The forming star, called a
protostar, is the product of a collapse
of a giant cloud of molecular hydrogen and "dust". As it gains mass, it gains more gravity, growing
ever more dense and hot. The protostar is shrouded by the cloud material during its formation,
which begins to flow about it in a rough orbit. The closest particles are pulled into the protostar
adding to its mass. The centrifugal force prevents some of the gas from falling into the protostar,
and eventually forces the spinning gas to form a disc shape, by conservation of angular momentum.
In cooler regions of the disc, away from the star, the cloud can have some solids and "dust" and
begin to form small masses. Of these, a few rocky masses grow large enough to have sufficient
gravity to form a planet. In the outermost portions of the disc, the largest masses are possible.
When the star finally ignites, the initial solar wind it creates is thought to blow away the lighter
particles comprising most of the disc, leaving only the more massive planets. The newly formed
planets still occupy their respective positions in the plane of this disc, spinning around the star
circular elliptical orbits.
If Anubis were a failed star, it probably would have the orbital characteristics of a companion star
in a binary star system. A binary star system has two stars, a larger, and a companion that have
formed more or less at the same time. When a protostar forms, sometimes the disc, of H2 and dust,
flowing about it is unstable. Part of the disc may collapse under its own local gravity and begin
to form a companion star, just as what happened to the original star. The orbit of the companion
would be highly elliptical, as is the case with most binary systems. The most recent discovery of a
brown dwarf orbiting
Gliese229 has many trying to make out its orbital characteristics to confirm
that it isn't a super planet. Brown dwarfs tend to have highly elliptical orbits, not having formed
with the other planets. Anubis occupies a roughly circular orbit in the plane of the terrestrial
Secondly, the location of Anubis in the solar system is consistent with that of an outer planet formation in our solar system. Terrestrial planets tend to be closer to the star than larger Jovian planets such as Jupiter. The largest solid masses, 10 or more times earth mass, tend to form at a greater distance from the star, where the temperature is lower. A gas giant, like Jupiter, is thought to have a very massive solid core initially. The greater gravity allows it to capture and retain the lighter elements such as hydrogen and helium, which eventually make up the bulk of its mass after it is completely formed.