protoplanet

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protoplanet

(proh -toh-plan-it) An evolving planet in the process of accretion, together with any of its satellites forming by accretion at the same time in the vicinity of the planet. The dust cocoon around some T Tauri stars has the attributes of a protoplanetary system. In the one typical case, HL Tauri, it forms a flattened disk, radius 160 AU, containing about one Earth mass of dust; allowing for dust condensed into planetesimals and the system's gas content, it could condense into several planets. Infrared observations from the satellite IRAS show dust around over 40 slightly older stars, including Vega, indicating either a protoplanetary system or a swarm of comets. See also Beta Pictoris.

protoplanet

[′prōd·ō‚plan·ət]
(astronomy)
A precursor of one of the giant planets, which is believed to have formed, along with its satellites, from a minisolar nebula in a manner similar to that of the formation of the sun and planets.
References in periodicals archive ?
The one that is favored by most planetary scientists is termed the Giant Impact Theory or, much less formally, the Big Whack, in which a Mars-sized protoplanet, named Theia by astronomers, smashed into the primordial Earth about 4,500,000,000 years ago, when our solar system was taking shape.
The investigations show that the amount of angular momentum taken away by the mass loss from a set of identical protoplanets is in excellent accordance with observation.
Lastly, water, once it is formed, must be gathered together on a protoplanet before life can evolve--essential sequencing.
The protoplanets that receive minor amounts of heat energy cool off fast and the endogenous activity in them ceases.
In young-star accretion disks, accretion is the method by which protoplanets become planets, while in old-star accretion disks, it is the method by which an old, compact star captures material from a companion star.
There were millions of these scattered throughout the solar system at first, but as they became larger, their increased gravitational attraction pulled other planetesimals to them becoming protoplanets.
The obtained images will reveal the fundamental inner disk structure and allow us to search for planet-related disk surface features, such as tidally cleared gaps or hot accretion spots around embedded protoplanets.
In addition to detecting dust traps, ALMA can see disk gaps carved by condensing gas giants and could even resolve the protoplanets themselves.
These streamers are almost certainly guided and shaped by protoplanets embedded within them, Casassus says.
Astronomers haven't yet directly spotted any protoplanets around HD 142527, but they keep looking.
The young star, which is a pre-main sequence object, is believed to have two protoplanets currently coalescing in orbit around it - giving the system its vivid and thick bands of dust separated by deep gaps.
With a diameter of approximately 530 kilometres, Vesta is the one of the few protoplanets in our solar system still intact today.